Thank you, thinkatory, for looking this over for typos and also for being my anime consultant! All mistakes are my own.

The piranhas were the main issue right now.

Actually. No. It was the citrus that was the main issue right now. The piranhas were great! She'd bred them to live in a tiny square of blue tile that didn't always, strictly speaking, even exist! She'd trained them to materialize on command! But... they couldn't tell the difference between lemon and orange scent.

"Come on, guys, work with me here," she muttered under her breath, then prepared to run them through the training again, but her heart wasn't in it. Maybe this was beyond what magical tilespace piranhas were capable of being trained for.

She took a whiff of her orange scent, and then of her lemon scent. Honestly, they did smell pretty much the same. Also, now she really wanted lemon bars.

Her phone made a little jangling noise, and she jumped. It was a new text! ...How did she even have reception down here, anyway?

She picked it up, cringing already. It was probably from Undyne wondering where the hell her best friend's cool new puzzle was and why it wasn't done yet. She actually had three or four texts from Undyne that she hadn't looked at yet, because if she did look at them she'd have to reply and if she replied she'd never be able to say anything cool and Undyne would think she was an idiot, which, let's face it, she totally was, and -

And.

And it was a picture of a bunch of spider donuts. From Sans.

i got a buncha these things, you want any? papyrus dozen like junk food and i donut know what else to do with 'em!

She groaned. But! Yeah, she could go for a break right about now.

Im always here for garbage food. Wait no, that would make it sound like she was insulting his choices or something. She backspaced. I didn't know you were so passionate about spiders. She sent it, and then cringed. Oh well, it was already sent. She hurried to the elevator out of the basement; Sans would be here any second now. She was pretty sure he could teleport and she was really curious how he did it, but it was probably rude to ask. Besides, she had some theories, and none of them were very happy ones.

nah i'm just passionate about donuts, he texted back. i worship them. they're holey to me.

She just facepalmed, and went to open the door before he could knock. Sure enough, she found him at the door, one fist raised. "Hey," he said.

"Hi!" She tried very hard to look cheerful. It was probably easier if your face was permanently affixed into a grin, she decided.

"You look like you need a break," he said, decisively, going past her into the lab. He paused at her desk, evidently looking for somewhere to put the box of donuts and finding nothing but her vast mountains of clutter. "I like what you've done with the place," he said finally.

"It's, uh. S-sorry, it's kind of a mess. I'm just really busy with - with Royal Scientist stuff?" she finished hopefully. "You - you know how it is, I g-guess."

"Yeah," he said, tonelessly. "Anyway!" he said, a lot more brightly, "let's relax and have some donuts." He pulled a picnic blanket from literally nowhere and spread it out on the floor of the lab.

"Does, uh. Does Muffet know you made off with all her donuts?" Alphys asked.

"Eh," said Sans, waving a hand dismissively. "So. You still working on that horrible tile puzzle?"

"It's. …yeah! It's going really well. It's…." She sighed.

"You're stuck, aren't you?" Sans asked.

"Yeah," she admitted.

"You know you don't have to do it, right?" he said. "I mean... Papyrus knows you must be really busy, he's not gonna be upset. Plus, I have to say, I'm not real excited about fishing him out of the middle of it if he gets stuck on a puzzle."

"Ha," she said, joylessly. "F-funny you should mention the, uh, fishing."

To her horror, he took this entirely the wrong way. "Aw, come on, Undyne's not gonna hold it against you either," he said.

"N-no, that's, that's n-n-not what I -" Words failed her and she just buried her face in her hands for a moment.

"Although, now that I mention it, Undyne did seem kinda worried about you," he said. "You're not answering your phone, or something? She said maybe you were mad at her."

"Oh no," said Alphys, diving for her phone. Those four texts. "Augh, I am the worst kind of trash, I'm a terrible friend, I c-can't do anything right!" she moaned.

Sans was managing to make a perma-grin look dismayed. She brought up the texts, ignoring him for the moment.

hey, was wondering if you wanna do a human history movie night with me and Pap tomorrow?

Then the next day:

super last minute, sorry. watched Cooking w/Killer Robot marathon. maybe next week? something w/giant swords? YEAH!

And then:

Is everything ok? Miss you.

And finally:

Did I do something wrong?

"Oh no," she moaned.

"That bad, huh," he said, sympathetically.

"Oh nooo," she repeated. "Oh no, oh no, now she probably thinks I'm terrible and -"

"Alphys. Wow. Relax," said Sans. "I came over to check on you and make sure you hadn't been, I don't know, eaten by lab rats or something."

"Eaten?!" she asked. Did he... did he know? Augh, when had she last fed the amalgamates, anyway? Two days ago, maybe? Ugh, that was too long, they were going to be all grumpy when she went downstairs next. She tried to keep breathing and not panic.

He held up his hands to pacify her. "Hey. Hey. I don't know why but everything I say's making you panic." He nudged the box towards her. "Look, have a donut. Everything's better with donuts. It'll make you feel hole again."

Alphys winced despite herself, then sighed. "Okay, yeah. Sorry. I'm. It's - it's been a hard few days."

"Yeah?" he asked.

She nibbled at the donut half-heartedly. "So uh. You mentioned the tile puzzle thing? I'm having trouble with the piranhas."

Sans snorted. "I'm sorry, just - there are piranhas? Why are there piranhas?"

"They were in the specs Undyne gave me!" Alphys said, trying not to get defensive.

"Sounds very fishy to me," said Sans. "Anyway, why not just make robot piranhas? I mean, that's your forte, isn't it?"

Oh god, robot piranhas would be about ten times worse. "It's not making the actual piranhas, as such," said Alphys. "It's getting them to distinguish between lemon scent and orange scent. Because, see, the request was to make sure they go after anyone who smells like oranges but be repelled by anyone who smells like lemons."

Sans stared for a moment, and then, to her dismay, started laughing. "What? What? You're serious. Oh man, I bet Papyrus came up with that one. He's - he's pretty picky about his cleaning products, I guess that little difference is important to him." His grin widened a little. "Papyrus is so great at those little details, you know?"

"Sans, this isn't f-funny!" said Alphys. "Have you ever tried to train killer fish to distinguish between d-limonene and l-limonene when all they care about is smelling blood?! Because I have!"

"Yeah, that sounds like one l of a problem," said Sans. "A terrible knot you have to d-tangle. Orange you glad I stopped by?"

"Sans," said Alphys, beginning to lose patience.

"It sounds like you need this problem like a fish needs a by... cyclohexane! Lemon know if you think of anything I can do to help."

"Sans," she said. It was starting to become more of a whine.

"Citrus me, I got this. I don't rind helping you at all," he said, because he was a merciless bag of bones.

She glowered at him. Then she took the box of donuts away from him.

"Hey! I was eating those!" he protested.

"Tough," she said. When he leaned over to try and reach them, she harrumphed and stood up. Getting to his feet was apparently too much for Sans, because after one last halfhearted sitting lunge, he gave up and sat serenely on the picnic blanket.

Alphys carefully balanced the box of donuts on top of a stack of papers on her desk, then slid an empty mug underneath it for added support. With a few keystrokes, she brought her computer out of sleep mode and was drawing up her data on the piranhas. "I'm not really sure h-how you can help?" she said. "I-I mean, if you can it'd be great, obviously, b-but... don't you do, uh, physics?" Her memories were kind of fuzzy on this. Why did she know Sans again? When had she met him? It wasn't that important, was it? Everyone knew Sans.

"Yeah, but, everything's physics in the end, right?" Sans said, a shrug in his voice.

She finished her donut before saying, wryly, "That's what physicists tell themselves. I g-guess if it helps you sleep at night..."

"I sleep all the time," Sans said cheerfully. She wondered if he was ever going to get up and come over here eventually.

"Undyne has mentioned," she said. "So, uh, w-what exactly do you think is so physics-y here?"

"Well. It's not so much the physics, I guess," he said. "It's just that I'm really good at cheating."

She reached absently for another donut, opening the box without looking at it and reaching inside. Her claws closed on something rubbery, and before she could stop, it was making a ridiculous farting noise.

She pulled the whoopee cushion out of the box, and turned to look at Sans. He hadn't moved an inch from where she'd left him, and was snacking on a donut he definitely hadn't had before.

She sighed. "Y-yeah, I can see that." She turned back to her computer screen and skimmed the data she had on her attempts at training the piranhas. Ugh. No statistically significant difference between any of the training methods she'd attempted and the control groups.

Sometimes she wished science worked more like it was presented in fiction: less waiting around for something to happen, more moments of genius and day-saving. On the other hand, as it turned out, horrific abominations of science were a real thing. Who knew?

"So, h-how exactly were you thinking of cheating?" Her mind wandered to some of those weird diagrams she'd come across deep in the lab files, presumably belonging to the previous Royal Scientist. "Are you thinking, um, t-time travel? Because if I could find some way to breed selectively for citrus recognition they could evolve to-"

"No," said Sans, and she leaped back with a squeak of shock, because suddenly he was standing right next to her and he was speaking in a freaky hollow voice, and also the light in his eyes had gone totally dark and, and, what the fuck, Sans?! "...Heh, sorry," he said, and the little glowing dots returned, and the grin looked more natural. "Just. Trust me. Time travel, not a good idea."

She knew she shouldn't ask, but she kind of had to. "...Why?"

"Time flies," said Sans. When she frowned at him, he added, "They're even more annoying than fruit flies. And they get stuck in your teeth if you go faster than light. It's a real problem."

Okay, yeah, she wasn't gonna get a straight answer out of a guy who wore bedroom slippers everywhere he teleported. Fair enough.

"Out of curiosity," he said, "why didn't you make robot piranhas?"

"Ugh," she said. "You know, I thought about it? B-but then I'd have to invent the scent organs and I'm n-not sure I'm up to it." She wasn't up to a lot of things, honestly. She wasn't sure why Asgore hadn't noticed. Or Undyne. She was really surprised Sans hadn't noticed, though. He was weirdly observant.

"Nah," said Sans. "Just think lazy!"

"But I don't want to leave the piranhas out! Then Undyne and your b-brother will be d-disappointed and I won't be the 'g-great Dr. Alphys' anymore, I'll just be a f-fraud. They s-specifically requested piranhas!"

"So give 'em piranhas," said Sans. "But play to your strengths."

"I d-don't know that I have any strengths," she pointed out.

"Sure you do. I mean, right now you've only been using biology. Maybe you wanna get down to the nuts and bolts of the matter. You made Mettaton, right?" he said. She tried not to wince. "And if you can make that guy a star, you've gotta be good. Plus, I can't help but notice you're, uh, pretty good with optics."

She blushed. "The c-cameras? They're for - uh, for scientific observation?" she said.

"Riiight," said Sans. "I know what you're up to. You just wanna steal all my best knock-knock jokes, don't you?"

"There's no s-sound!" she insisted, but Sans was chuckling. "...is that what you do at the door all day?" she asked, frowning. "I just thought you were, uh. T-testing the structural integrity of the door. And... talking to someone?"

"Nah," said Sans. "Who would I be talking to?"

"On the other side of the d-door?" she suggested.

He shrugged. "Anyway. Just some suggestions. But if you wanna give up... hey, I can't blame ya. Papyrus will recover from his disappointment. Undyne probably knew it was a crazy idea in the first place." He reached around her to grab another donut. "Anyway, I gotta go on my lunch break before she finds out I'm slacking off here. Text her back, though, she seemed pretty worried. And try to do it before she and my bro burn the house down with her stress-spaghetti-ing?"

"Thanks," said Alphys, half-heartedly. She turned to ask another question, but found she was sitting in an empty room. "...I think. ...well, hey, at least I have donuts."

She rolled her eyes at herself. She knew people meant well, but... sometimes encouragement was worse than nothing at all, because she felt like even more of a failure when she didn't live up to it. Plus there'd been that dig about the cameras. They were for important security things, though. And not just, uh, fanfiction research. Not that she could help it if little details slipped into her stories, though. You couldn't help knowing things. Also, it did explain why apples had mysteriously appeared in front of a different camera each day last week. An apple a day... ugh, it was so obvious.

She frowned, and x'd out the data on her computer screen. It was totally useless garbage. Basically just like her. Garbage in, garbage out. And, bored, she tabbed over to the cameras, to see if anything interesting was happening to people who weren't her. The specially waterproofed ones in Waterfall were mostly showing Onionsan having a one-sided conversation with that grumpy puzzle-loving monster, and Woshua rinsing off the lenses, and...

"Alphys, you're a moron," she muttered to herself. She went hunting for the last robot fish design she'd made, pulled up the waterproofed cameras, and started working on ways to miniaturize them. Undyne and her friend would have piranhas! It would be a glorious day for science! Or, at the very least, it would make the puzzle ten times more dangerous. Probably Asgore wouldn't like it. But Undyne's grin would more than make up for that. She smiled to herself.

Then she remembered the other thing Sans had told her, and picked up her phone. Should she call?

Oh god no. That was way too terrifying.

Hey Undyne! Sorry I didn't get back to you, my phone died! Can't believe I missed ur movie night! She pressed Send.

Ill go thru the archives for some stuff u havent already seen. We saw most of what I have already lol. How about giant robots w/swords?

And after that sent, she had an amazing idea, and she grinned.

Hey, what if I made a 100% authentic giant human sword for you?

She put aside her anxiety to keep working on the robot piranhas, but when her phone buzzed again, she had a brief moment of worry.

Then she saw what Undyne had sent:

! OMG REALLY?

She blushed a little. I can draw up specs after I finish these robopiranhas for u and papyrus, ok? Come over 4 ice cream 2morrow + I can take measurements. If Undyne was distracted by ice cream maybe she wouldn't notice how much Alphys was sweating? Probably?

The response came almost immediately.

Piranhas? ICE CREAM? Alphys you are the BEST.