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ENTROPY

Chapter 13: Rising

Warning: This chapter contains body horror

Are there dogs inside?

All of the Fallen monsters were moved to the Hotland laboratory over the course of a few days. Things in town went back to normal fairly soon afterward. Where there had been a pall of grief and sorrow hanging over Snowdin like a cloud, now people were tentatively hopeful. Everyone seemed to be assuring themselves that good news was on the way. The change in atmosphere did nothing to alleviate Sans's doubts, but it was nice all the same.

Sans had tried calling Alphys once after seeing her at the Laboratory, but she hadn't even picked up-though he wasn't actually sure that it was anything personal. Other monsters had said much the same after other attempts to contact her. Mettaton mentioned on one of his programs that the Royal Scientist was working very hard and was not to be disturbed, and that if people really wanted to call someone, they should call into one of his shows, anyway. King Asgore had also given a formal request to let the Royal Scientist work in peace. People had stopped clamoring for news after that, and things had settled back into the usual routine over the next week and a half.

Sans decided to just check out a few engineering books, both from the Snowdin Librarby and from the New Home Library, but the selection at both left a lot to be desired. He'd hoped to maybe just teach himself some basic engineering and finish his time scanner that way, but it was quickly apparent that the basics just weren't going to cut it. He could take a four-year program in engineering and still not have the knowledge or skills necessary. He needed Alphys. So once again, it was a matter of waiting. Eventually her experiments with Fallen monsters would end, and then maybe he'd finally be able to talk to her. If he assured her that he would never bother her again afterward, maybe she'd even agree to help him with only minimal coercing.

In the meantime, Sans usually found himself selling hotdogs, practicing knock-knock jokes at the Ruins door, or helping Papyrus set up the last of his revamped puzzles between the Ruins and Snowdin Town. The puzzles now included a completed electricity maze, several switch puzzles, and a high-tech randomized tile puzzle designed by Alphys herself. Sans's contributions amounted to exactly zero puzzles total, a point that Papyrus brought up at least twice a day.

Currently, Papyrus was showing Sans his very latest human trap.

"A plate of spaghetti?"

"NO ONE COULD POSSIBLY RESIST A PLATE OF FRESH SPAGHETTI! I even left a microwave so that the EVENTUAL HUMAN may heat it up once it is…SLIGHTLY LESS FRESH!"

Papyrus gave the microwave an affectionate pat. Sans decided not to point out that it wasn't plugged in, nor were there any outlets out here in the woods. Papyrus had already lugged the thing out here, as well as the table the plate and microwave were resting on.

"I think this spaghetti is frozen, bro."

"TRY TO PAY ATTENTION, SANS!" Papyrus stamped a foot. "THAT IS WHAT THE MICROWAVE IS FOR! NYEH! In any case, I plan to REPLACE the spaghetti portion of this trap DAILY!"

"Neat. Pretty good trap, then. This'll really tangle anyone coming by."

"OF COURSE IT'S A GOOD TRAP! EVERYONE-UGH, SANS, THAT WAS BARELY EVEN A JOKE!"

"Heh."

Papyrus grumbled and folded his arms. "ANYWAY, no human NOR monster NOR animal, apparently, will be able to pass up an opportunity to try some of the GREAT PAPYRUS'S INCREDIBLE COOKING!"

"Animals too, huh."

Sans was about to make an animal magnetism joke, but Papyrus jerked a thumb toward a small rock formation.

"Mice, at least! There's a mouse that's been trying to get at my spaghetti all day!"

Sans looked where Papyrus was pointing. There was a tiny crevice in the rocks, exactly mouse-sized. As he looked there was a tiny squeak, almost as if the creature was listening.

"Huh. Didn't know there were any mice in Snowdin. Thought they were mostly in Waterfall and New Home. Isn't it too cold for mice?"

"MICE DO WHATEVER THEY WANT, SANS!" Somehow, Papyrus made this sound sage. "Who am I to judge such a CONNOISSEUR of good cooking?"

Sans took a few steps closer to the rocks and crouched down to see into the hole better. The occupant was standing boldly near the entrance, watching Sans with curious black eyes, like drops of oil. The mouse's fur was white-not exactly common among wild mice.

Out of nowhere, it occurred to Sans that it had now been almost ten years. Maybe ten years exactly, maybe a little more. It was impossible to pin down the actual time frame, and Sans had long since given up on trying. A decade. Ten years since Gaster had given him a simple task-recharge some random magic gauge that regulated the temperature in the mouse cages-and Sans had told him that he couldn't. Ten years or so since someone had told Sans that four test mice had escaped, and that in a fit of rage, Gaster had destroyed all the remaining mice. Ten years, give or take, since everything that had happened.

A decade of trying and failing to piece everything back together. And here was one of those pieces, staring up at him through too-intelligent, oildrop eyes.

"Aww, man." Sans's grin broadened as he met the mouse's gaze. "Would you look at that. Heh. You're one…determined little guy, huh."

"Are you talking to the mouse? CAN MICE TALK?"

"Nah." The mouse retreated further into its hole, out of sight. Sans stood back up and gave his brother a placid grin. "Heh."

"What's that look for?" Papyrus eyed Sans with suspicion.

"Nothin'. I just…remembered something funny."

Papyrus put his hands on his hips, seemingly annoyed. "Well, KEEP IT TO YOURSELF! We should move on! I want to show you my idea for the GAUNTLET OF DEADLY TERROR!"

"Sure, bro. Lead the way."

Papyrus marched onward deeper into the forest. Sans followed, casting a backwards glance at the mouse hole. For a moment, he thought he saw beady eyes watching him again.

He wondered if the other three had survived as well.

At the base of one of the many cliffs in the Snowdin forest, Papyrus had constructed a model out of snow. It was absurdly complex considering, but Papyrus had always had a bit of an artistic streak. The snow model depicted a long bridge, blocked with more hazards than was strictly necessary, including swinging axes and maces.

"Pretty impressive snow sculpture, bro."

"The real thing will be even MORE impressive!"

"Where you gonna get a bridge this long, though? Don't think there's any chasms that wide." Sans poked what appeared to be a small snow dog perched on the bridge, and the snow dog promptly crumbled. Papyrus made an annoyed sound.

"WELL, NO!" Papyrus shifted Sans out of the way so he could shape the snow dog again. "I'm planning on painting that big rock formation right outside the entrance to town! There, that's better. DON'T TOUCH IT THIS TIME, SANS!"

"Sorry."

"I'm going to start construction later today, and I need the model to be PERFECT! It's not PERFECT if it's in pieces, brother!"

"Okay." Sans raised a brow ridge at Papyrus. "I said I was sorry."

Papyrus sighed and put his hands on his hips, frowning at the snow, looking oddly distant for a moment.

"It's alright, Sans. That dog is ALWAYS annoying, even when he's a tiny pile of snow! ANYWAY! I want to show you the next trap I've constructed!"

"Is it far? I love seeing your puzzles, but my tibias are starting to ache. Ain't telling fibulas."

Papyrus groaned loudly. "Somehow, your puns are WORSE today than usual! It's not THAT far, Sans, don't be such a LAZYBONES! Even that MOUSE had more gumption than you!"

"Heh." Sans looked away, grinning faintly. "Well, not like that's hard."

It was a wonder the little guy was even still alive, actually. Mice didn't live more than a few years. Effects of Determination, maybe? They had given up on studying the substance before really learning all that much about it. The only real case study for the effects of Determination on a living thing was Gaster himself and, well. That was a pretty damn flawed case study.

Papyrus was saying something. Sans blinked and pulled himself out of his thoughts.

"What? Sorry, I was spacing out."

Papyrus glared at him, expression going from annoyed to outright frustrated.

"If you're going to be TOO LAZY TO EVEN PAY ATTENTION, then maybe you SHOULD just go home! You don't even HAVE any puzzles out here to calibrate, SO! WHAT'S THE POINT!"

"Hey…come on, bro don't be like that. I said sorry. I'm just kinda distracted today, that's all."

"Do you even CARE about my puzzles and human traps?"

"Of course I do. I always do."

"THEN! PAY ATTENTION, AND LET ME SHOW YOU THE LAST ONE, AND STOP COMPLAINING! It's not that far, so KEEP UP!"

Papyrus started walking at a brisk pace. Sans stared at his retreating back for a moment before trotting to catch up.

"Alright, alright, no more complaining. Jeez. You're in a mood today."

"THAT SOUNDS A LOT LIKE COMPLAINING!"

"No, it's commentary." Sans was already starting to lag behind as Papyrus kept up his pace. "Paps, is everything okay?"

"It's FINE, Sans! You're just being MORE ANNOYING than usual!"

Sans grumbled under his breath. "Okay, whatever. Shutting up."

The two of them lapsed into irritable silence. Papyrus got into moods like this from time to time, and usually there was something that set it off. Usually that something was Sans. Sans had known pretty much since childhood that the best course of action was to just apologize and stay quiet until whatever it was blew over.

Technically, that was his default reaction to most things.

Papyrus led him deeper into the forest, heading in the direction of the bridge and the Ruins door. Sans fell further and further behind, as Papyrus didn't seem to want to slow down for him. That was fine. Papyrus didn't need Sans right on his heels; Papyrus could probably use a bit of a break from him right now.

Eventually, they reached the bridge over the chasm. Sans noticed the trap immediately. It was less a trap per se, and more the fact that the bridge was now fixed. The wood was pristine and raw, and the whole thing looked quite sturdy.

"Oh, hey. You finished it."

"YES! With Doggo's help, it went quite smoothly! As smooth as a WOOD FINISH! NYEH HEH HEH!"

Sans grinned at joke, but decided not to comment on it. Mostly because he wasn't sure he'd be able to resist making one of his own, and jokes seemed to be a point of contention right now.

"It looks real good, bro. Bridge like that will last a hundred years."

"THANK YOU, SANS!"

Sans stepped closer to examine it better, studying the odd addition to the bridge. Papyrus had built what looked like vertical bars across the bridge, but they were spaced far enough apart that Sans wasn't sure what their purpose was. Maybe a stylistic flair? They looked like they'd make actually crossing the bridge unnecessarily precarious.

"So what're the bars for?"

"TO STOP HUMANS, OF COURSE! THE GREAT PAPYRUS HAS COME UP WITH A VERY CUNNING TRAP. If the humans are coming from the Ruins, then! THEY MUST CROSS THIS BRIDGE! But where they expect to find a bridge, they instead find-A FENCE! No human will be able to get through!"

Sans chuckled a bit and Papyrus narrowed his eyesockets at him.

"NOW what is funny?"

"Heh, the bars are too wide, bro. A human could just slip right through. They're not all that big."

Papyrus stared at him, and Sans realized he had made a mistake. Sans stuffed his hands in his pockets and waited for it.

"I THOUGHT! YOU WERE DONE COMPLAINING, SANS!"

"Sorry, Paps." Sans grinned sheepishly. "It's not really complaining, just-"

Papyrus stamped a foot. "I WORKED VERY HARD ON THIS TRAP, BROTHER! AND ALL YOU CAN DO IS CRITICIZE IT!"

"Heh, it's more like construction criticism…"

"SANS!" Papyrus yelled so loud his voice echoed off the cliff face nearby. "ENOUGH! WITH THE PUNS! I AM TIRED OF THEM!"

"Okay." Sans stared at the snow between them. "Okay, sorry."

"YOU NEVER TAKE MY TRAPS SERIOUSLY! YOU NEVER TAKE ANYTHING SERIOUSLY!"

"Hey, come on. Ease up, bro."

"I AM NOT STUPID, SANS!"

Sans looked up at him again, frowning. "I never said you were. I've never thought-"

"EVEN IF THE BARS ARE TOO WIDE, IT'S NOT ABOUT STOPPING A HUMAN! IT'S-IT'S ABOUT SLOWING ONE DOWN, SO THAT I MAY CAPTURE IT! THERE IS NO POINT TO A HUMAN TRAP IF IT DOES NOT HELP YOU CAPTURE THE HUMAN!"

"Okay. I got-"

"NOT THAT YOU WOULD UNDERSTAND! YOU HAVE NEVER LAID A SINGLE TRAP OUT HERE OR DESIGNED A SINGLE PUZZLE!"

Sans decided to just shut up and wait for Papyrus to finish. He probably deserved this. Shouldn't have said anything about the traps and puzzles at all.

"YOU ARE SO LAZY! YOU NEVER WORK HARD AT ANYTHING! ALL YOU DO IS SLEEP AND SLACK OFF, AND YET SOMEHOW EVERYONE LIKES YOU! EVEN THOUGH YOU DON'T TRY TO MAKE FRIENDS, BECAUSE YOU DON'T TRY AT ANYTHING. BUT ALL I DO IS TRY! AND YOU'RE MAKING FUN OF ME FOR IT!"

Sans kept his hands in his pockets and his gaze on the snow. He hadn't really meant to laugh. It had just seemed…amusing. Like making the bars too wide was a simple, silly mistake.

Papyrus threw up his arms. "WHY DID YOU COME OUT HERE AT ALL IF YOU WERE JUST GOING TO MAKE FUN OF ME? WHY DID I EXPECT YOU TO TAKE SOMETHING SERIOUSLY FOR ONCE?"

"Okay." Sans raised his voice just enough to be heard. He started walking, moving past Papyrus and heading back the way they'd come. "I'm, uh. I'm gonna let you cool off a bit. I'll be at Grillby's. Sorry I upset you."

"OF COURSE YOU'RE GOING TO GRILLBY'S! I WOULDN'T BE SURPRISED IF YOU WERE ON THE PARTY-PLANNING COMMITTEE!"

Sans kept walking. "No idea what you're talking about."

"THE PARTY THIS WEEKEND!" Papyrus yelled after him. "THE COSTUME PARTY YOU WEREN'T GOING TO TELL ME ABOUT!"

Sans stopped and sighed heavily, shoulders sagging. He turned back to his brother, rubbing the spot between his eyesockets.

"Papyrus, I don't…have any idea what you're talking about. What party? I didn't hear anything about a party."

It didn't seem like the best time for anyone to throw a party. But then again, maybe that was the whole point. Monsters were like that. When bad things happened, they tended to throw themselves into something happy and positive, a sort of aggressive attempt to cheer themselves up. It made sense. Sinking into despair was dangerous for a monster.

Papyrus didn't answer right away, and after a moment Sans looked up at him. Papyrus looked like he wasn't sure whether to be suspicious or surprised. He had his arms folded across his chest and his eyesockets were rather wide.

"YOU MEAN YOU…really don't know about it?"

This was exhausting. "No one told me about any party, bro. I pretty much just woke up, and then I was-slacking off on some stuff, and then I came out here with you."

Sans saw Papyrus grip on his arms tighten. He frowned down at the snow for a moment before looking back up at Sans.

"I thought-I suppose I thought you'd heard. It's going to be QUITE BIG, I think most of the town will be there…"

"Is that why you've been in a bad mood all day?" Sans stared off into the woods. "You thought there was some secret party I wasn't telling you about?"

"You-keep A LOT of secrets, brother! I thought this was one of them!"

Sans didn't answer. No wonder, then. No wonder Papyrus was upset. It was probably just one more thing on the pile. One more disappointing thing his useless older brother had done. And then Sans had gone and teased him over his traps. It was a wonder Papyrus didn't lose his cool more often.

A wonder he put up with him at all.

"I am-Sans, I am SO sorry."

Sans sighed again and closed his eyesockets.

"You don't gotta apologize, bro."

"YES I DO! I should not have jumped to conclusions! I should not have yelled. I was just…frustrated. I…I suppose I am just…I thought perhaps you knew that I had not been invited, and were trying to spare my feelings."

"I get it." It was something Sans would probably do, after all. Wasn't that the whole reason he kept most of his secrets from Papyrus?

He gave a vague shrug. "But it sounds like I haven't been invited either, so. Although that's…kinda weird. If it's big enough to include most of the town, why exclude us?"

The townsfolk weren't even remotely that petty, and it wasn't like Sans or Papyrus had done anything terrible to deserve being shunned. Frowning, Sans pulled his phone out of his pocket so he could check his messages. He was terrible about checking them regularly, and there was at least a dozen he hadn't read.

"Especially the Great Papyrus," Sans said, scrolling through his phone. "Everyone loves that guy."

"If that's true, then why…?"

Sans looked up when he heard the shake in Papyrus's voice. Papyrus was hugging himself now, staring down at the snow and looking forlorn.

"Why aren't I more popular, Sans? Why don't people like me?"

"What? Paps, everyone likes you."

"But I don't have any friends."

Sans stared at him.

"You-Papyrus, that's just not true. What about the dogs? What about Undyne?"

"Undyne is the Captain of the Guard! She does not have TIME to be friends with someone who isn't even a guard! She certainly does not think of me that way! I am just her student!"

Sans was positive that that wasn't true. Not with the way he'd heard Undyne talk about Papyrus.

"And the other sentries? Our neighbors? The dogs?"

"They all just…put up with me! I am not close friends with any of them! Doggo…Doggo was the one who told me about the party, but he did not invite me!"

"Jeez, that's…that doesn't sound like him. He's kind of an idiot, but he's not that dense. Usually. Maybe…" Sans scrolled through his phone some more, casting around for some reason why Doggo would bring up a town-wide party directly to Papyrus's face, and then fail to invite him.

Seemed like the mutt needed a talking to.

"Maybe he just knows you don't like Grillby's? You said it's at Grillby's, right? And you're not a fan of that kind of frivolity. Maybe he figured you wouldn't want to go."

"That is EXACTLY what HE said!" Papyrus squeezed his eyesockets closed briefly. "He said he would invite me, but that he knew I wouldn't like it! And I probably wouldn't! I DESPISE Grillby's! And I don't like how rough the dogs' parties can be! But I still want to be INVITED, Sans! I just-want to be INCLUDED! I want to know that people WANT ME AROUND!"

Sans was quiet for a bit, eyelights dimming. This wasn't anything new; it wasn't coming from nowhere. This had to be the sort of thing that had been building up for a long time, that was only now starting to come out. How long had this been going on? How long had Papyrus felt so…so lonely, so left out?

And how the hell had Sans never even noticed?

At that moment, Sans found a message in his phone that he had missed: Costume party at Grillby's - Saturday!

So there it was. Sans pocketed his phone.

"Well…" Sans spoke slowly, trying to choose his words with caution. He didn't want Papyrus to think Sans was pitying him. Papyrus had never once pitied Sans, even though there were plenty of times in Sans's life where he would have deserved it.

"It looks like-like there's just been a whole lotta miscommunication here. I, uh, seems Grillby sent me a message about the party earlier and I ignored it. So…I'm invited. Which means, yanno, that I can-extend the invitation to you."

Sans chanced a glance up at Papyrus to see how he was taking this. Papyrus's face was unreadable.

"I mean, if. You want to, that is. Cause, even if no one else does-and I really think they do, Paps, even if you can't really see it-well, yanno. I always want you around."

There was a silence, and then Papyrus sighed. It was less exasperated and forlorn than before.

"You are my brother, Sans. You are SUPPOSED to! I just…want FRIENDS! I know I'll have LOTS OF FRIENDS once I get into the Royal Guard, but! I want friends BEFORE that!"

Sans wondered if this was his fault. He had clung to Papyrus like a leech his entire life, taking up most of his time, and probably also most of his energy. Papyrus must not have felt like he could just go out and make friends if he had to look after his needy, clingy older brother the whole time. No wonder Sans had never noticed how bad it had gotten. He was selfish. He was the problem.

And he didn't know how to fix it. This was the best he could do.

"Do…do you want to go to the party, bro? It's a costume party. I have an idea for something that'll really stand out. You'd, heh. You'd have to beat potential friends off with a stick. It'll be at Grillby's and it'll be loud and hectic, but…you could use it as a chance to talk to people. Take a break from all the puzzles and sentry stuff and-maybe make some friends, right? If you want. No pressure, bro. And it's not-it's not just some kinda pity invite. I legit have a really good idea for a costume that'll be as cool as the guy wearing it. I just, uh. Want you to be happy, yanno?"

Papyrus was quiet for an uncharacteristically long amount of time. It was still hard to read his face. He was still hugging himself, still staring at the snow. Sans held his breath and waited, desperately hoping that he was doing this right.

After what felt like an eternity, Papyrus let go of his arms and spoke.

"What…kind of costume did you have in mind?"

Relief flooded Sans's marrow and he gave a tentative grin.

"Something cool, bro. I'm thinking…famous, unbeatable hero. Intergalactic warrior who travels the cosmos and saves whole worlds. Something like that. With like, armor. And a cape. Even cooler than the Royal Guards."

Papyrus smiled just a little.

"That…SOUNDS LIKE THE PERFECT COSTUME FOR THE GREAT PAPYRUS!"

"I got the rest of the day off if you, uh, wanna go get started on making it. I saw some pretty good stuff at the dump the other day we could use for materials. We could make it a project. Still a few days till the weekend, and if we're gonna make it really cool, it might take awhile."

"THIS IS A GREAT IDEA, SANS!" Papyrus was smiling in earnest now. "You REALLY want to help me make it?"

"Sure, bro." Sans spread his arms. "It'll be fun."

"That is-VERY NICE OF YOU, BROTHER! Then let's go home and get started right away!"

He started marching back toward Snowdin, and Sans fell into step beside him. This time Papyrus's pace was slow, so that Sans could keep up. Sans kept grinning as they walked. Thank god they'd managed to salvage this. He hated it when they argued; it made his soul feel pinched and painful.

"Sans, I…really am sorry. That I shouted and that I said those things."

"Aww. It's okay, Paps." He reached up and patted Papyrus's arm. "I'm sorry I teased you about your traps. They're all real good."

"Well…" Papyrus rubbed his chin. "You MIGHT have been right about the bars being too wide on the bridge."

"It's still a good bridge. You know, I… wood have hated it if I kept having to take a shortcut back and forth." Sans nudged Papyrus with his elbow. "Eh?"

"UGH, Sans!" Papyrus was hiding an obvious smile. "Terrible as usual!"

Sans laughed, feeling himself relax.

It was a pleasant afternoon in Snowdin Forest. Sans was supposed to be manning his station, but he had let himself take an extended break. No one ever really came out this far to make sure the sentries were doing their jobs, after all. And with his position now right in front of the Ruins door, it wasn't like he would miss it if a human did come by.

The spot was just too perfect. It had quickly become Sans's favorite area in the whole woods. Private, quiet and out of the way, like his favorite spot in Waterfall-the tiny little side cave with nothing but a bench and a single Echo Flower. He could nap, or practice magic and knock-knock jokes without any fear of being disturbed. And it was less boring than sitting at his station for his entire shift. Far be it from him to ever take a job a hundred percent seriously.

He reached up and rapped on the door twice, stretching as he pulled himself out of a nap.

"Knock knock. Who's there? Beats. Beats who? Beats me."

Things had been pretty hectic in town as people got ready for the party. It was nice to see Snowdin coming back to life. The party seemed to be a sort of combination of the town cheering itself back up, and sending good vibes to the Fallen monsters at the Royal Scientist's lab. Everyone was still very unclear as to what was even happening, but the idea that their loved ones might one day return to them had filled people with hope. Even if it was false hope, it was…nice to see everyone happy again.

He reached up and knocked again.

"Knock knock. Who's there? Cows go. Cows go who? Nah, cows go moo, buddy. Heh."

Meanwhile, Papyrus's costume was coming along real nicely. They were planning on finishing it tonight, with plenty of time left before the party tomorrow night just in case. The thing was mostly done already, and Papyrus was more excited than Sans had seen him in years. They'd decided to forego the cape idea in favor of Papyrus's favorite red scarf. It was easier for the smaller piece of fabric to flap dramatically in the wind, after all.

Sans knocked again.

"Knock knock. Who's there? Owls go. Owls go who? See, now you're gettin' it."

Sans raised his free hand and summoned some bone bullets. They sprang up from the ground in rows, very close together, the array wide enough that it spread across the entire path. Sans had gotten an idea from Papyrus's bridge with its too-wide bars. A fence-or a cage-was a pretty good way to trap someone, after all. It was the kind of attack that couldn't be dodged or avoided at all. If the anomaly that Gaster kept warning him about was so dangerous, maybe Sans would need something like that. Not that he expected to have to fight anything. Gaster had made it sound like it was maybe a person or something, but how could a person be an anomaly? It was more likely that Gaster was referring to some kind of glitch or hiccup in the flow of time.

Whatever it was, it would be coming from the door. Sans was no closer to figuring out what the anomaly was, or talking to Alphys, or finishing the timeline scanner, but that didn't mean he could just sit back on his coccyx. Not entirely, at least. He had to be ready for anything.

Wasn't he always?

He let the array of bones vanish, then reached up and knocked twice.

"Knock knock."

"Who is there?"

Sans bolted upright, so startled he reflexively teleported about five feet away from the door. He stumbled backward, then promptly fell over on his butt. He stared up at the door, eyesockets wide.

Someone had answered.

But that was impossible. That was simply impossible. No one lived in the Ruins, at least not as far as anyone knew. Maybe the occasional monster burrowed its way in, but it couldn't possibly be that common. Sans must have just been hearing things.

He squinted at the door, holding his breath and waiting to see if something happened.

"Who is there?"

The voice came again, louder this time. It was a woman's voice, formal-sounding, her tone practically demanding an answer. Sans looked around, as if maybe the voice could be coming from somewhere other than beyond the door. Like maybe someone was playing a prank on him.

But it was true. Someone was living in the Ruins. He had knocked, and someone had answered.

Sans picked himself up and walked back to the door. He should ask her who she was, or maybe explain himself, maybe just apologize for bothering her. Or maybe he should just not answer at all.

Instead, he replied with,

"Dishes."

There was a pause.

"Dishes… who?" She sounded confused. Even for a monster, "Dishes" was a pretty unusual name.

"Dishes…" Sans grinned sheepishly. This was probably one of the stupider things he had ever done. "…a very bad joke."

There was another pause, longer this time. Sans was sweating. She would probably start yelling at him any second.

Instead, she burst out laughing.

It was loud, raucous laughter, the kind that would have her entire body shaking. Absolutely joyous, unapologetically gleeful. She sounded like she hadn't heard something so hilarious in years.

It was one of the best laughs he'd ever heard in his life. No one had ever laughed like that at one of his jokes, especially not one that terrible.

Sans sat down again in front of the door, chuckling despite himself. Her laughter was utterly infectious.

As her howls of mirth began to peter out, Sans knocked again.

"Uh, knock knock."

"Oh goodness!" She sounded like just talking was difficult. "Who is there?"

"Spell."

"Spell who?"

"W-H-O."

"Pfffthahaha!"

He listened to her break down again, dissolving into fits. God, did she always laugh so earnestly? He had to find out.

"Knock knock."

"Oh dear, another one! Who is there?"

"Nobel."

"Nobel who?"

"No bell, I knock."

She went off again. It was positively delightful. She must really like bad jokes. That was perhaps somewhat anomalous behavior, but would some kind of existential threat laugh like that? Sans didn't think so.

He rattled off a few more, trying to come up with his very best. None of them were particularly good, but that didn't seem to matter. She laughed at every single one, and she laughed hard. It was incredible. Even when he was doing stand-up at the MTT Resort, no one ever laughed this hard. Occasionally a joke would land really well, but it was usually a one in a dozen shot.

After a few minutes, she begged him to let her catch her breath, so he did so. He listened to her come down slowly, still giggling. She sounded like she had taken a seat against the door.

Then, in yet another unexpected move, she knocked twice.

"Knock knock."

Oh man, he was in for it now. His grin widened even further.

"Who's there?"

"Old lady."

She was keeping her composure very well. It seemed that even her delivery was top-notch.

"Old lady who?"

"Oh! I did not know you could yodel!"

"Oh my god." Sans pressed a hand to his face, laughing. It was as terrible as all the ones he'd told, and that just made it funnier. She was very, very good at this.

"Man-man, I gotta admit, stranger, I don't think I've ever met a real bad joke enthusiast other than myself till now."

"I have always loved jokes! And sadly, I so rarely find myself with the opportunity to tell any!" She chuckled brightly. "This has been a delight! I have not laughed so hard in ages!"

"Well jeez, good thing I showed up when I did. Glad I could delight up your day some."

"Oho! That was a good one! How…ah, enlightening to hear you have more than just knock knock jokes. You must be quite the comedian!"

"Heh, well, I do have a comedy routine over at the MTT Resort. I do okay. I'm not much for the limelight, though."

"I have not heard of this 'MTT Resort.' I have lived here in the Ruins for a very long time now, you see. I am afraid that I am, hee hee, somewhat in the dark about more recent developments in the Underground!"

"Yeah?" That was interesting. Mettaton had built his big fancy resort hotel right next to the Core awhile ago-probably over a year now. She did sound a bit older than Sans, and she had an old-fashioned way of speaking. She might have been in the Ruins for years and years, all alone except for the missing branches of the spider clans and the occasional ghost..

Sans scooted closer to the door.

"Well, it's this big hotel over in Hotland, run by Mettaton. You heard of Mettaton? He's the bright star of the Underground."

Everyone and their mother had heard of Mettaton. If she hadn't, then she truly was living in total isolation.

"No, I am afraid that the name is not familiar. I have not… met a ton of people over these last few years!"

That one was just downright clever. Sans couldn't hold back another bout of laughter.

"Heh, wow, you really are good at this."

"Ah, I have thought of another one! Knock knock."

"Who's there?"

"To."

"To who?"

"No, that is incorrect! It should always be 'to whom!'"

Incredible.

Sans lost complete track of time. He and the lady on the other side of the door chatted for hours, mostly telling jokes and trading puns. She was remarkably easy to talk to, and he ended up telling her a few things about the state of things in the Underground, as well as a few things about himself. She in turn chatted about the Ruins-apparently there were vast networks of puzzles inside, probably an ancient holdover from the war, when monsters were still uncertain about whether humans would follow them underground or not. All these puzzles needed to be maintained, and the lady was the self-appointed caretaker of the Ruins. Mostly, she said, this just meant keeping things clean and running.

She also wasn't quite as alone as Sans had thought, which was both heartening and rather fascinating. Apparently there was a small loose-knit community of monsters within, mostly loner-types like Migosps and Looxes. It was as Sans had guessed-most of them had simply burrowed or flown into the Ruins one day and had just decided to stick around. The lady didn't interact with any of them very often, except to make sure they were staying out of trouble. She said she had a feeling that they found her intimidating.

Eventually it was evening, and Sans remembered that he had agreed to help Papyrus try and finish his costume that night. He had also completely missed the end of his sentry shift, but that was fine. Clearly no one had even noticed. For all that it was one of the more important sentry positions in the Underground, no one really cared about it all that much.

"My apologies," the lady said. "I had no idea it had gotten so late."

"Nah, I lost track of time too," he said, getting to his feet. "But it was worth it. Not every day I meet someone who likes bad jokes as much as I do."

"Nor I! For obvious reasons, I suppose."

"But yeah, I gotta get back home. Hoping to finish Papyrus's costume tonight."

"Ah, for the costume party you mentioned! It sounds like it will be quite the soiree. Is Papyrus a friend of yours?"

"He's my brother," Sans said, grin widening. "Basically the coolest guy in the whole Underground. He's really looking forward to the party. Mostly for the chance to show up looking like a super cool warrior."

"He sounds lovely! Well, I hope you and he have fun! Thank you for telling me so many wonderful jokes today. It really did brighten things up in here."

"Heh, glad I could shine some light into your life." Sans hesitated, tapping his thumbs together. "Hey, you know, I come out here all the time. Mostly just to hang-nice and quiet and all. You think, uh, maybe we could chat again? I know way more jokes."

The lady on the other side paused for a moment.

"That…you know, that would be quite lovely! I was actually going to ask you just about the same thing, but I feared that perhaps you were merely passing through. It would-indeed be very nice to speak to you again."

Sans practically beamed.

"Awesome. Well, uh, I'll try to come by tomorrow before the party. But if not then, then probably the day after. I work as a sentry right nearby."

"How convenient! Then, I hope to speak to you again soon."

"Heh. Right back at ya. Talk to you soon."

With that, Sans left and headed back to close up his station. There was something of a spring in his step. Who'd have thought that someone so interesting lived in the Ruins, of all places? It had been a very, very long time since he could say that he had actually made a friend. He'd almost forgotten the feeling.

It was a nice feeling.

There was a practical benefit to this whole thing as well. If she lived in the Ruins, and apparently knew it like the back of her hand-or paw or hoof or what have you-then she might be able to see the anomaly coming long before Sans did. She might be able to warn him, give him a bit of a headstart. He wasn't sure how to broach the topic of anomalies, or timelines, or cryptic warnings from existentially-challenged former bosses, but at least it was an option.

Though it occurred to him that they hadn't even exchanged names. He'd been so caught up in the joking that he'd completely forgotten to ask. Maybe that was for the best. She must like her privacy if she had locked herself away in the Ruins. Plus it kept a certain air of mystery to things.

More important than all that was the fact that Sans had made a brand new pun friend. He couldn't wait to see the look on Papyrus's face when he told him.

It was the biggest party Snowdin had seen in years. Most of the town showed up, even if only for an hour or two, as well as some monsters from the rest of the Underground. There was also the usual array of party crashers. The whole thing began inside Grillby's, but as more people showed up it spilled out into the streets. Undyne and a few of the guards arrived, both to participate and to try and keep the peace. The latter turned out to be not necessary-Snowdin had a reputation for rowdiness, but that usually just meant a few drunk dog monsters wrestling in a snowbank.

The fact that it was a costume party instead of a random excuse to get drunk helped. There were enough kids there that even the real party animals kept themselves in check. Most people were in costume, and the mood was jovial.

Sans and Papyrus showed up early, since Papyrus didn't believe in being fashionably late. Papyrus was practically vibrating the whole way to Grillby's, equal parts nervous and excited.

"You do not think we could have improved my costume at all?" Papyrus had asked. "MAYBE WITH GLITTER! Or a sword!"

"No way, bro. You're gonna be the coolest guy at the party."

Papyrus's costume was perfect as far as Sans was concerned. He looked truly epic when a breeze caught his long scarf. Papyrus had always cut a pretty dramatic figure, but between the stylish boots, the chestplate and the scarf, he looked like a seasoned warrior ready to risk life and limb to save the day. He looked like a hero.

It helped also that, by contrast, Sans had of course gone for the laziest costume possible. He'd simply gotten a plain T-shirt and written "2,000 lbs" on it in marker. A skele-ton. Papyrus hated it, of course.

As soon as they walked into Grillby's, Sans knew he'd had a good idea for once. Everyone who even saw Papyrus complimented him on his costume. Total strangers started chatting with him, and it wasn't long before Papyrus settled into his usual role as a social butterfly, striking heroic poses the whole time. This should get him some of that popularity he so craved, if not a few new friends. Sans let him be, since at this point Papyrus didn't need him around to potentially draw away attention. He slipped away and took his usual post at the bar so that he could people-watch.

It was a good party. Snowdin had finally gotten its happiness back. It had been a long two weeks.

Sans, always content to hang back and not get involved, stayed at the bar for most of it, chatting to anyone who bothered to come by and say hello. This was mostly the Grillby regulars. Punky had plenty of sarcastic commentary about all the visitors to town, particularly anyone from the city. He was one of a handful of people not wearing a costume, saying it was "too establishment." Dizzy came by to flirt, share a few drinks and eventually fall asleep in one of the booths, like usual. She was even worse than Sans was about that, which was saying something.

Midway through the night, Sans was able to track down Doggo and corner him.

"Next time you're telling my brother about a party?" Sans said, voice level. "Make sure you actually invite him too."

Doggo squinted at him. "Jeez, sorry. I figured there wouldn't be a point. I know he doesn't like these sort of things, plus he hates Grillby's."

"Fair. But telling someone about a party and then not inviting them is pretty dang rude. Yanno?"

Doggo rolled his eyes. "Fine, fine, I got it. You're always looking out for him, but you realize I do like the guy, right? Everyone likes Papyrus. It wasn't anything personal-but whatever. I'll apologize to him."

"Thank you. I appreciate it."

"You know, you act like you need to defend him, but if he's really going to be a Royal Guard someday, his big brother rushing to his aid will be the last thing he needs. You're sheltering him too much."

"Heh." Sans turned and walked away, back to his place at the bar. "Tell me something I don't know."

Sans went back to drinking slowly and watching the party. It was nice. Everyone was happy, having fun. Despite the noise, Sans felt rather at peace.

Grillby also appeared during one of his breaks, looking exhausted.

"Hey, buddy. You're looking burnt out."

Grillby gave a soft hiss, like a sigh, and leaned on the counter.

"Should have hired more temp help." Grillby's voice was soft, barely audible above the din.

"Well hey, having all the food buffet-style was a good idea," Sans said, grinning widely. "At least no one's broken any windows yet?"

"Yet."

"Great party, though. Just what we needed around here. Everyone's happy."

Grillby was silent for a little while, idly wiping out a glass.

"You seem happy as well."

Sans glanced at him. "Pfft, 'course I am. I'm always happy. Always smilin', right?"

Grillby didn't have much in the way of facial features, but Sans got the sense that if he had eyebrows, he would be raising one right now.

"Not always happily."

Sans looked back toward the party, not sure how to answer. Grillby had always been ridiculously perceptive, but Sans had thought he'd been doing pretty okay for himself. Usually the endless jokes were enough for people not to look too closely.

"Yeah, well." Sans shrugged. "I'm happy right now, at least."

There was some kind of spatiotemporal anomaly coming, and he still needed to get Alphys's help, but-his brother was having a grand time at this party, no humans had shown up for over a year, and Sans had met someone with a sense of humor like his own. He'd even managed to go out and chat with her a bit before the party. At least in this exact moment, things weren't so bad.

"I am glad," Grillby said with a nod.

At that moment, Doggo climbed up on one of the tables and started barking loudly. Sans snickered to himself as Grillby made an annoyed series of crackling sounds, pushing himself off the counter.

"Had to happen eventually," he hissed.

"Everyone! Everyone, listen up!" Doggo said in between barks as more and more people turned toward the noise.

Then Dogamy climbed up on the table beside him and began barking for attention as well.

"Please, everyone! We have an announcement to make!"

"Listen up!"

Grillby was already starting to make his way across the bar toward them.

"Just a moment, Grillby, this is important!"

Doggo held up his cellphone and waved it. Sans could tell that both of them were drunk, but this sounded like more than just drunken shenanigans.

"I just got a call from the Royal Scientist!"

"Dogaressa received one as well!"

That shut up the room almost entirely. Even Grillby stopped, folding his arms and waiting for the two dogs to get to the point. Sans watched from his stool.

"Dr. Alphys says that the monsters who had Fallen Down have all gotten back up!"

"She saved them!" Doggo barked. "All of them are alright!"

"They will be returning home to us sometime tomorrow."

"They're all coming home!"

The entire restaurant exploded into noise as people started cheering or asking questions or proposing toasts. All of the dogs started barking with excitement. On the opposite side of the room, Undyne scooped Greater Dog up into a crushing hug. Grillby trudged back toward the bar to get everyone a fresh round of drinks.

Sans watched the whole thing, tapping his finger against the side of his empty glass.

"Huh."

She'd cured them. Alphys had somehow cured all the Fallen monsters. It seemed like the perfect end to a great day, but…

If nothing else, it was the perfect opportunity. Alphys had to be ecstatic after such a success, which meant she might be amenable to talking to Sans. So he slid off his stool, made his way to a more shadowed corner of the bar, and teleported.

He landed in Hotland, right in front of the Laboratory door. The transition from loud noise to total silence was a little jarring. Sans stepped closer to the door and knocked.

He waited a minute, but there was no answer. Sans knocked again.

No answer.

That was kind of odd. It was late, but not so late that Alphys would be asleep already. She tended to stay up until the wee hours, anyway. Plus she had to expect that maybe people would want to come by to congratulate her, or even come try to collect their family members early.

Sans pressed the intercom button on the side of the door.

"Al-uh, Dr. Alphys? It's, uh, Sans. You in there?"

He stepped back to wait and see if she answered. When she didn't, he pressed the buzzer again.

"I heard about the Fallen monsters. It's pretty freaking amazing. I know you're probably really busy, and I know no one's supposed to bother you, but uh…"

The longer he stood here, the more awkward he felt, all the excitement and contentment of the party fading. He still had no idea what to say to her. And she must be really happy right now, knowing she'd saved so many lives. Wasn't his presence just going to ruin that?

But…there was still that but. Something about this felt oddly familiar. Fallen monsters got up on their own sometimes, but the reasons for it were always inexplicable. If Alphys had discovered some way to bring people back from Falling, it would be the most important scientific accomplishment in probably a century. A manual, scientific cure for Falling.

Why did that seem familiar?

He pressed the button again.

"Dr. Alphys, are you there? Listen, I-I don't want to interrupt or put a damper on things, but I-I still need to talk to you sometime. So if you're there, could we maybe just…think of a time in a day or two for us to talk?"

He was going about this all wrong. Maybe he was too tipsy to be thinking straight. This was probably coming off as pretty stalker-ish behavior. Even if she was inside, she might just be ignoring him.

He wished he could just leave her alone. That would be so much better for her.

Sans sighed and pushed the button a final time.

"Alright, well. Congrats on saving those people."

With that, he took a few steps back and teleported, landing outside his and Papyrus's house. It was an unceremonious way to end the night, but Sans didn't feel like going back into the noise of Grillby's. He was tired. It felt like there was a weight on his mind.

The monsters that Alphys had cured did not return the next day.

Everything progressed as usual. Several monsters from the community took it upon themselves to help clean up Grillby's and the adjacent streets. Papyrus spent an hour or so in the morning regaling Sans with stories of people he had met at the party, saying that he was certain several of them would be his friend now. Visitors from other regions of the Underground checked out of the Snowed Inn and departed one by one, and Snowdin returned to its usual quiet self. The Guard Dogs went on their patrols, Sans worked a shift in Waterfall and another shift at his sentry station/hotdog stand in Hotland. Papyrus refused to change out of his costume and went on patrols still wearing it, then left for an evening training session with Undyne. Sans went to Grillby's as soon as work was over, like usual. The dogs were sitting at their usual table, all looking various shades of confused.

The Fallen monsters hadn't come back, and there was no word from the Royal Scientist as to why. Or any word from her at all. Sans heard Dogamy assuring the others that she probably just needed to keep them an extra day for observation. To make sure they were truly stabilized.

But the monsters didn't return the next day, either. Nor the day after that.

When three days had gone by, word started getting around that Dr. Alphys was not returning calls, texts, or emails. When four days had gone by, people started knocking on her door, but no one ever answered. At five days, people started asking Mettaton, who just shrugged and encouraged people to tune into his newest show.

A week went by. The Fallen monsters still had not returned, and Alphys had seemingly vanished from the face of the Underground. It was then that people began to ask King Asgore directly.

The King informed the families that Dr. Alphys was certainly still alive, as she had answered at least one of his calls, but that was the extent of his knowledge. All she had told him was that she "wasn't ready yet," so Asgore encouraged patience.

Most people found the whole thing suspicious, and Sans was no different. He stopped by the lab one more time himself, but if she wasn't going to answer for concerned family members, she certainly wasn't going to answer for him. Normally he would have been content to just wait and see what happened, but the odd weight in his mind, the odd sense that he had forgotten something, made it impossible not to think about.

He took to spending more time in his own lab, rereading all of his notes from the past several years, tinkering with the machine and the scanner. He hadn't kept things very well organized, so he decided to sort things out, try to arrange his notes and research chronologically. He pored over the data dumps that he and Alphys had managed to get from the time machine's damaged CPUs. He'd been over all of it before, but none of it had ever seemed all that pertinent. Most of it was nonsensical, probably from the machine attempting to to run scans as it passed through the void, and the rest of it was either error messages or structural information from the machine's degradation. Everything else had been lost.

Looking over and rereading everything helped refresh his memory, bringing a few things that had gone fuzzy over the last few years back into focus. He found himself studying the machine's nonsense data again. Represented visually, it was all long, unique strings of numbers, some with very little internal repetition, others with none at all. The actual amount of strings seemed to be gargantuan, but the machine had only retained twelve, as well as a portion of a thirteenth. After exactly 31,121 digits, each string ended in exactly twenty zeroes. Sans had always found that strange. 31,121 was a pretty specific number, and it couldn't be a coincidence that each string of numbers degraded into zeroes after that many digits. The zeroes themselves seemed significant as well, but given that the whole thing was just a bunch of numbers out of any sort of context, Sans couldn't for the life of him understand it. Nor did he know any mathematicians.

He toyed with the numbers idly for a few days, either in the lab or while bored at his sentry stations. He tried converting some parts of the strings into binary or hexadecimal or base-11, but it didn't produce anything all that interesting. He also took a closer look at the areas of repetition within some of the strings, and also compared instances where a digit was the same number between multiple strings. All of it seemed to be entirely random. Sans couldn't get his head around it, and trying was giving him a headache.

Maybe he could plug all the numbers into the scanner once it was complete. But that of course implied that it would ever be complete, and with Alphys all but missing, that was currently up in the air.

Fortunately, he had Papyrus and the lady through the door to distract him. Papyrus had not taken his costume off since the party, and had taken to calling it his "battle body." The lady through the door had started discussing baking in between rounds of jokes. She was an avid baker, mostly of pies.

"Man, sure hope I get to try a slice someday," Sans had said one day after she described her particular method for apple pie.

"Oh! Maybe…maybe someday."

It was clear by now that she had no intention of opening the door anytime soon. She referred to her stay in the Ruins as a sort of self-imposed exile. When Sans had asked why, her tone had gone soft and she'd said only that it was because of a disagreement with someone she had once known. That was all she said on the matter, and Sans didn't press.

"In the meantime, perhaps I can give you one of my pie recipes!"

Baking and cooking in general were things Sans had never had much interesting in, partially because cooking had sort of become Papyrus's thing over the last few years. He wasn't exactly keen on learning an entirely new skill, but it would be nice to have something in common with his door friend other than just a love of jokes. Plus it was a distraction from numbers, anomalies, and Alphys.

Still, the number strings stuck with him, and he was never sure why. They had never really stood out to him before, but these days it was like there was some kind of pattern he was missing. He was a monster like any other, for the most part, so the idea of a pattern he couldn't understand was like an itch he couldn't scratch.

One night, almost two weeks after Alphys had cut off all contact with the outside world, Gaster came to him.

It was remarkably ordinary dream, probably one of the most unadorned dreams Gaster had ever created. Sans sat in a black void, absolutely nothing around him. The floor, or ground, seemed to be made out of black glass. When Sans looked, he saw faint white characters crawling beneath the surface. Not Wingdings, which was Gaster's usual prerogative. There were myriad white circles with diagonal slashes through them, or a pair of curly brackets-braces-with nothing in between them. The symbols darted and skittered beneath the glass like fish in a pond.

"Huh. This one's new. It's barely even nightmarish, Doc."

"STOP. LISTEN."

Gaster's nonexistent voice was sharp enough that Sans looked up. There was of course nothing to see.

He hadn't actually seen Gaster in…well, technically he had never seen him at all.

"Okay. Listening."

"NOT MUCH TIME. YOU WILL WAKE UP SOON."

"Well, you've got my attention while-"

"EMPTY SETS."

Each symbol beneath the glass flashed brightly, all in unison.

"Set theory." Sans propped his chin on a hand, watching the symbols. "Well, I guess from that perspective, the void counts as an empty set."

"YES." Gaster's sounded urgent. "EXACTLY."

"So how does this relate to the anomaly?"

"YOUR ZEROES." Sans felt a brief pressure on the top of his skull, as if someone had gently tapped him. "THINK, SANS."

"My-?"

Sans woke up.

It was much earlier than he usually got up. Papyrus, of course, had already awakened and gone out for a morning shift. Sans had several hours before he needed to be anywhere, so he got some leftover coffee from the kitchen and went right down to his lab. He went back to the number strings again, bringing them up on his computer and scrolling right until he found all the zeroes.

Twenty zeroes at the end of each string. 31,121 digits, then twenty zeroes.

Sans set aside the fact that there were specifically twenty for the moment. The significance lay in the zeroes themselves. The series of zeroes was the only thing that every string had in common. It wasn't too much of a leap to assume that every possible string-and that was something like 31,121 to the power of 10-must also end in zeroes.

Zeroes had pretty obvious connotations. It meant that whatever information the time machine had been scanning came to an abrupt end after a given number. That information could be just about anything, and the number itself could represent anything from distance to time. The point was that it ended. The zeroes were something coming to an end.

And Gaster had been pretty specific for once. Mathematical symbols for empty sets-a set with nothing at all in it. A void. Sans highlighted the zeroes in one of the strings and changed it to an empty set symbol: a circle with a diagonal line through it.

All of these strings of numbers ended in a void.

Sans got to his feet, pulled on his coat, and teleported to Hotland.

He landed right out front of the Laboratory. He checked to make sure no one was around, then walked up to the front door and knocked. There was no answer, but he hadn't really expected one.

Sans pressed the buzzer.

"Al? Dr. Alphys. It's me. I need to talk to you. It's really important-I think I found something."

He stepped away from the door, actually pacing back and forth a few feet, feeling more agitated than he had in ages.

Alphys didn't answer. Frustrated, Sans hit the buzzer again.

"Dr. Alphys, I don't know what's going on in there, but I don't really care. I know you don't want to talk to me, but this is-something's wrong. Something's fundamentally wrong, and I need-I need your help."

No answer. Sans stepped back, scrubbing at his face. He didn't know what to do. Something was starting to take shape in his mind-a theory, a horrible one. He'd been laboring under the assumption that the anomaly Gaster kept warning him about, over and over, was simply some kind of hiccup in the timestream. Maybe some kind of…temporal fracture or something, and Sans had figured that the worst case scenario was another divergence, like had happened when Gaster was erased. The effects something like that could have were far-reaching and nigh-unknowable, but not necessarily deadly.

This was different. Something-several somethings-were ending. There was no way of knowing what was ending without the timeline scanner. It could be as benign as literal, physical roads that came to dead ends, or it could be as dire as lives.

Sans had a very bad feeling that it wasn't something benign.

He knocked again, louder and more desperate this time, but of course there was no answer. She wasn't going to answer. Alphys was the only one who could do this. Sans had briefly considered tracking down another engineer, but Alphys was the only one who had ever worked with pre-divergence technology. Any other engineer would be hard-pressed to even understand some of the mechanical theories involved. Alphys had always said that the circuitry alone was completely baffling.

He stared at the door. All bets were off now. If she wasn't going to come to him, then he would just have to go to her. It was a messed up thing to do, but he was running out of time and options.

Sans took a breath, glanced around to double-check that no one was nearby, then teleported into the lab.

He landed just inside the door. This was the first time he had ever been inside since Alphys had taken over as Royal Scientist. The entire building had been renovated, and everything was completely unrecognizable. It seemed most of the interior walls had been knocked down in favor of one large laboratory space, with some doors leading to what Sans assumed were closets and side rooms, and apparently a bathroom. There was now an escalator leading up to the second floor, and that seemed to be where Alphys's living quarters were. The main laboratory area was dominated by an enormous split-screen TV monitor, with what looked like several dozen video feeds of different areas of the Underground. It looked like Alphys had set up cameras just about everywhere. Other than the screen, there were a few workbenches and some basic laboratory machinery.

The whole place was a bit of a mess, moreso than Sans had expected. He'd been to her apartment plenty of times-while Alphys wasn't exactly tidy, the lab looked more like Sans had been running things. He wondered if that was a recent development or not.

The lab was devoid of life, and silent but for the hum of fluorescent lights.

"Dr. Alphys?"

Sans's voice echoed through the lab. He waited near the door for a moment, but there was no answer. He wondered if he'd been wrong. Maybe she wasn't here at all; maybe she'd holed up somewhere completely different.

"Alphys?" He tried again. "Sorry, I kinda let myself in."

Still no answer. If she was here, he had a feeling she would have come out by now to confront him. Unless she was really upset-then she might just keep hiding.

Sans found himself hesitating again. He hated going about things this way. This was invasive, just walking into her lab like this, practically tracking her down. He had never been good at sticking to any sort of personal morals, but Alphys had been a friend once. He didn't belong here.

But what choice did he have?

He began searching the lab, checking the video screen to see if there was anything telling there, opening a few closets, peering up the escalator. Barging into her actual living space was where he drew the line, at least for now. If he couldn't find her today, he could come back tomorrow. He called her name a few more times, but there was still no answer. Nothing on any of the workbenches seemed to indicate what she had been working on. Most of it seemed to be related to Mettaton, if anything.

Sans hovered near the escalator, tapping his chin and frowning. She wasn't here, at least not in the main lab, and he had a feeling he would have heard something by now if she was upstairs. She could be in the basement, but that was assuming it even still existed. They might have just filled the whole thing in during the renovations. There was now a bathroom where the old elevator would have been.

Though that in and of itself was kind of strange. Sans didn't know the first thing about architecture, but positioning a bathroom over an elevator shaft seemed like it would affect the plumbing.

Sans went and knocked on the door, just in case. There was no answer of course, but the door was cracked open already, so Sans pushed it open the rest of the way.

It wasn't a bathroom. It was an elevator.

"Okay. That's…weird."

Why disguise an elevator as a bathroom? Maybe she was using the basement as her real lab? Considering how little there was in the way of actual laboratory equipment here on the ground floor, it made sense. Sans knew the basement had maintained more of it's original, pre-divergence structure, so she would have way more space down there.

And if the elevator was disguised, it meant that probably no one even knew it existed. Alphys had always said that her work was extremely classified, so that made sense too.

She might be down there right now. Sans sighed, mentally braced himself, then walked to the back of the elevator and hit the button.

It was kind of funny, he thought as he rode it downwards. The last time he had actually used this elevator, he and Gaster had been bringing the time machine to the Core.

The elevator dinged, and Sans stepped out into a hallway. It was even quieter down here, the lights much dimmer. He could tell right away that there hadn't been as many renovations down here. He couldn't really remember the old lab or its layout, but everything was very familiar. Even the floor tiles were the same. The hall was long, with no doors at all; it was completely empty except for a few screens on the wall.

"Alphys?" Sans called. "You down here?"

He headed down the hall, feeling more and more apprehensive with every step. It was oppressively quiet in here. Sans checked one of the screens, but they all seemed to be switched off. He kept going until he finally reached a large room with branching corridors. There wasn't much here either, except for a very large door with four locking mechanisms, some more video screens, and a vending machine.

Sans walked up to the door to try opening it, but all four locks were engaged. With no way of knowing where it went, Sans couldn't risk teleporting to the other side. He knocked instead, and the sound echoed down the hallways, much louder than Sans had anticipated. He cast a nervous glance down the halls as the echoes faded.

"…Alphys?"

Where was she? And if this was where she had been conducting most of her research, where were all the Fallen monsters? The lab seemed completely deserted-as deserted as the last time he'd been here.

"Man…" Sans said, running a hand over the top of his head. He'd started to sweat a little. "This is-"

A sound came from deeper in lab, a grumbling, groaning noise that Sans felt in his ribcage. Sans froze.

That hadn't sounded like machinery.

Sans looked around, watching for any sign of movement. It was impossible to tell where the sound had even come from-it was like it came from everywhere. Sans waited, perfectly still and silent, listening hard.

After a minute or so, there was another sound from further away-a discordant rasp, almost like a squawk.

"Okay."

Sans took a step back toward the hall with the elevator.

"Ooookay, then."

Something was down here, and Sans didn't think it was friendly. Maybe it was time to leave and try again tomorrow. Just go home, try to settle his nerves, try to work the numbers some more. It was probably cowardly, but Sans had never had a problem with that sort of thing.

He turned, and found the way to the elevator completely blocked off. For a moment, Sans thought some kind of door had closed behind him without his knowledge. But the thing blocking the hallway didn't look entirely solid. It was pure white, and oozing, some of it dribbling onto the floor.

"Shit."

A gaping black hole appeared in the center of the white mass, and the hole made a sound. It was like several animals growling in unison, pitched so low it made the floor tremble.

Sans stepped backward, and the thing disengaged from the wall and ceiling with a wet sound. As he watched, the mass twisted and shaped itself, the ooze forming into something like a body.

It looked like a monster, but it was like no monster Sans had ever seen or even heard of. It was enormous, maybe even bigger than a Boss Monster, twice as tall as Sans and maybe twelve feet long. As it finished shaping itself, six limbs formed along with a long, whipping tail. The black hole rose up from the thing's center, forming a sort of head around itself, topped with two pointed ears. The hole pulsated in time with its breathing, dripping black fluid.

The thing leaned toward Sans and made another one of those thunderous growls.

"Shit." Sans reeled backward until he was pressed up against the wall. "Holy shit."

The head lowered, and the creature took a menacing step toward him. Sans raised both hands, palms out.

"Hey. Hey, hey, easy, easy there, I-I don't mean any harm."

The ear-like appendages twitched and its head canted to the side, advancing again. It seemed like it was debating whether to charge or not. It growled again, and the whole surface of its body rippled like disturbed water.

"Can you understand me? Stop. S-Stop."

Shapes flickered in the black spaces between its limbs, like snarling faces. Sans's soul was hammering in his ribcage. He tried to press backward, but there was nowhere to go. He had to get out of here, he had to leave. This thing was going to attack any second, maybe even eat him.

It moved forward again.

"Wait. Wait, stay back. I-I don't want to hurt you, but-"

It snarled, gurgling and spilling black froth from the hole in its head. Sans inhaled sharply and summoned an array of bones above his hands.

"Stay back."

The thing seemed to hesitate. Its ears pricked, and its head canted back the other way. The hole pulsated a little faster and seemed to track the bone bullets as they moved. A different sound came from within it, almost like a dog giving an inquiring growl.

Sans frowned, glancing between the floating bones and the creature.

"What, you…you like these?"

He moved the bones a bit to the side, and the thing's head followed; Sans moved them the other way, and it gave another inquiring rumble. Its tail started to thrash erratically back and forth. Almost like it was wagging.

Even with terror gripping him, Sans thought he had an idea. He let all of the bones wink out except for one, then raised that one higher into the air.

The creature sat back on its haunches, or at least the impression of haunches, and looked up expectantly at the floating bone. Its tail thrashed faster, splattering white ooze onto the walls.

Sans stared at it, eyesockets wide.

"You're…you're kinda like a-?"

"No, stop!"

A shrill voice echoed from down one of the halls, and Sans was so startled that the bone vanished-right as the creature surged upward to try and catch it. The creature made a low keening sound as it lost its prize, and Sans teleported a few feet to the side. The creature crashed back to the floor right where he'd been standing. Sans backed away, summoning another array of bones.

"Stop!"

Sans looked over to see Alphys charging toward them from down the hall.

"Al-?"

"Endogeny, stop, stay! Stay! Sans, d-don't hurt them!"

The creature gave a warbling, roaring sound, stumbling back and forth on its six limbs, whole form vibrating. Its head whipped back and forth, as if searching for the missing bone. Sans moved backward and Alphys drew level with him, almost pushing him out of the way as she positioned herself between Sans and the creature. She looked terrified and exhausted, and her labcoat was filthy.

"Endogeny, stay! Stay, calm down! Sit! L-Look, look what I've got…" Alphys shakily produced a box of dog treats from under her arm, dug into the box and held one up to the creature. The thing gave a sort of prance and moved toward her, lowering its body, tail wagging.

"Good, that's good. N-Now sit, okay? Sit."

It sat back on three of its limbs. Alphys sighed in relief, and tossed the dog treat into the black hole. Sans couldn't see where it went, but the thing-Alphys had called it Endogeny-gave a happy-sounding whine and lay down, tail thumping against the floor.

"Good. Good dogs." Alphys stepped forward and patted its head. "God. Oh my god…I th-think my soul's going to explode…"

Sans tried to speak and his voice came out rather high-pitched.

"A-Alphys, what-"

She whirled on him, the terror back in her face.

"Sans, what the hell a-are you doing here?!" She turned away from Endogeny. "How did you g-get in here?!"

"I…I came looking for you, I needed… I found the elevator…"

"You can't be in here! You can't!"

"Wh-"

"D-Did anyone come with you? Oh god, did anyone else come down here?!"

Sans quickly shook his head. "No, no, it's just me."

Alphys dragged her hands down her face. "Oh, thank god, thank-S-Sans, you can't b-be here, y-y-you need to leave!"

"No, what-Alphys, what is all this, what-" Sans gestured at Endogeny, now vibrating peacefully on the floor. "What is that thing?"

"They're Endogeny, and th-they're not-they're not a thing, I can't explain it, Sans, y-you need to just leave, j-just leave and, and d-don't tell anyone what you saw, you never sh-should have come here! Why did you come here?!"

"I'm-Al, no, I can't leave. I need to talk to you, I didn't-I didn't want to break in, I just needed-" He stared past her at Endogeny, starting to shake.

He was starting to remember. Something was clicking into place. Fallen monsters getting back up, strange oozing dog creatures…

"W-We can talk later, I can't-"

"Alphys, what are they?" He couldn't stop staring at them, at the black void that made up their face. "What-what did you-?"

It couldn't be. It just couldn't be. It wasn't possible.

"Sans, later, I-I need to-"

"Are they-are they one of the Snowdin dogs?" Sans turned to stare at Alphys, his eyelights disappearing. "Doggerel? Doggo Sr.?"

One of Endogeny's ears twitched, but other than that, they didn't react. Alphys wrung her hands, digging her claws into the spaces between scales.

"Not-they're not one of them…" She was looking everywhere but at Sans.

"Alphys, what the hell happened?"

"I-I discovered this substance," she said haltingly, and before she could even get all the words out Sans was stumbling back against a wall. He clapped a hand over his mouth. He felt dizzy, like he was going to start retching.

"Oh god…"

"I-I didn't know it would go so wrong-"

"Oh my god."

"I w-was just-I was just trying to-"

All at once, Sans remembered something Gaster had told him in a dream, one of the worst dreams, one he had tried so hard to forget, years ago now:

SHE WILL MAKE ALL THE SAME MISTAKES.

Sans, for maybe the fifth time in his whole life, took off running.

"Sans!"

He ran down the rightward hallway, the direction Alphys had come from. He passed through a large room lined with hospital beds and saw something white and misshapen slough away into a vent before he could see it clearly. Sans kept running, turning down another hallway.

Even though the layout had changed, even though the basement laboratory had been renovated, he knew exactly where it was. There was one place it could be, only one area large enough.

And only one way Alphys could have gotten hold of a substance that had changed one of the Snowdin dogs so horribly.

Sans reached the largest room in the lab and skidded to a stop. There it was, looming from the ceiling, as enormous as he remembered. Alphys must have modified the design, but he recognized it instantly. Skull-shaped, with mandibles that curved down like pincers, two gaping holes like eyesockets, massive tubes curling away from the main structure into the ceiling and walls.

And it's shaped like a skull, he'd said, eons ago. I love it.

The Determination Extractor.

Alphys had built a Determination Extractor.

Sans fell to his knees. He stared up at it, breathing fast, shaking so hard his bones had started to rattle.

He barely even heard Alphys come scampering into the room.

"Sans? Oh god, Sans." She crossed the room to him, and he felt her grab his shoulder. "We have to go, please. Th-There's more of them down here, th-they get confused easily, you might, y-you might get hurt, please, you need to…Sans?"

"You didn't." Sans tore his gaze away from the Extractor and stared up at Alphys instead. "God, Al, tell me you didn't."

"I-how-?"

"Tell me you didn't. Tell me you-I don't understand." Sans clutched at the sides of his skull, thoughts scattering. "Everything was erased, I-I thought I'd gotten hold of everything that hadn't been, how-how did you-how could you have built it?"

"Built…?" Alphys jerked away from him, eyes widening in horror. She looked up at the DTE. "You mean-you mean you've-?"

Alphys started to scream, but slapped both hands over her mouth midway, cutting off the sound.

"No!" She dragged her hands away from her face, tears starting to leak from her eyes. "That was why the blueprints felt s-s-so strange, that was why- no, how could I h-have b-been so s-s-stupid?!"

She staggered, then crumpled to the floor near Sans, curling her tail around herself protectively.

"You found…you found blueprints?"

"It was during th-the r-renovations!" she wailed. "O-One of the workers found it under, under some rubble and as-assumed they were mine! It d-didn't even occur to me to question it, I just…I just took them, a-and when I looked at them later I, I knew something was wrong, but I didn't-I c-couldn't figure out what, and th-the design seemed w-workable, a-and I'd already been developing th-theories about, about a substance within the human souls, a-and the more I looked at the blueprints th-the more I realize they were e-e-exactly what I needed, and I didn't-I didn't question it!"

"But why not? Why not? You knew about the old Royal Scientist, you knew-"

"Because I'm not like you, Sans!" Alphys yelled, cutting Sans off. "I can't-I can't retain things like you can! I c-can't even remember his name anymore! This stuff, it just-i-it gets away from you, it goes all, all fogged over, and I couldn't…"

She trailed off and buried her face in her hands. Sans watched her, gripping the front of his hoodie with one hand.

"I should have known. I…"

Alphys sobbed into her hands. Sans looked away and stared at a point on the floor.

For awhile, they were both silent.

"You injected monsters with Determination."

"How-do you even know that word?"

"Because we studied it before." His eyesockets closed partway, and he lifted his head to look up at the DTE again. "This isn't my first time seeing that thing."

There was silence again but for Alphys's quiet sniffling. Sans stared at the floor, trying to collect himself. Trying to think. Trying to stop his soul from shaking its way out of his ribs.

"Al…"

She uncovered her face long enough to look at him. He met her eyes.

"We need to talk."