This is an Underfell fic.

Just a warning: Sans and Papyrus don't have a good or happy relationship in this fic. It's not stated directly, but Papyrus wasn't a good brother (I hesitate to use the "bad brother" tag because I'm not entirely sure what it entails but I'm pretty sure it implies incestuous rape and that at least didn't happen in the backstory for this.) I do have the whole story leading up to this figured out, but it's a story where I just spend like 90% of it putting Sans through the wringer so I probably won't write it out. Instead we can just straight to the happy ending!

The meeting had run long, as to be expected whenever the king brings in all the royal offices to discuss the state of the kingdom and dictate any changes necessary. The Captain of the Royal Guard had been a royal pain, as always, the Royal Head of Resource Management had been a delight, as was usual, and the Royal Treasurer could go eat a bag of dicks! Stubborn asshole, always trying to take over Gaster's budget as if he weren't fully capable of handing it just fine himself. Glorified accountant just needed to send him his cut and then bugger off, didn't she have enough to do without insisting on micromanaging every last piece of gold that went into every royal office?

Gaster took a deep breath, now was not the time to get lost in his annoyance. They were out in the open, he could vent when they got home. He glanced to his left, where Sans was walking next to him. Of course he'd brought his translator along for the meeting, that had become the norm just as much as Undyne destroying at least one piece of furniture before the meeting ended. Life was so much easier when he didn't have to keep reminding everyone to watch his hands when he spoke, and had the added bonus of Sans preserving tone and inflection when speaking for him, Janice was finally receiving the full brunt of his sarcasm. Gaster didn't know how he functioned before Sans came along.

But again, musings that were best left for when they weren't walking through the dangerous streets of New Home late in the afternoon. At the rate they were walking it would be a while until they were safely home, Sans's limp was more pronounced than usual, his pace slow and stuttered. The meeting must have been just as exhausting for Sans as it had been for him. Gaster had no illusions that the meeting itself had been the issue. Oh no, it was all a certain young, up and coming royal guardsman who had been guarding the meeting. From outside, of course. Gaster couldn't help but smirk as he remembered the jealous glare that burned into them as Gaster and Sans sauntered right past him.

Sans stopped, his body rigid, aggressive magic gathering around him. Gaster snapped back to the present. He looked around their surroundings, on alert for any approaching danger. They were on an empty street, shops locked up for the night, nary a monster in sight as the unnatural light of the Underground started to fade in imitation of the night that was surely falling on the Surface. Not a threat in sight.

Gaster looked down to Sans, who's every joint was a tense coil of tightly wound magic, a faint glow starting to gather in the few scars not hidden under his clothes. Sans nodded towards a narrow side alley before heading towards it. Gaster was loath to go near it, but he trusted Sans. As they approached the mouth of the alley Gaster heard the first faint sounds, some choked sobs and a few sniffles. Someone was crying.

A child was crying.

He wondered how Sans had heard it in the middle of the wide thoroughfare from the other side of Gaster. Then again listening was his job. Gaster let Sans take the lead as they entered the narrow space, he headed straight for the muffled sobbing. A small orange cat was was huddled between a pair of trash bins, wearing a dirty and ripped striped shirt under a pair of even dirtier coveralls.

"hey, you okay?" Sans crouched down a few feet away, making his already small frame as small as possible.

The child whimpered and cowered further into their miserable hiding spot.

Sans sighed, then started to take his coat off, teetering dangerously because he couldn't be bothered to get up from his crouch like a reasonable monster. Sans handed off the coat to Gaster, who carefully folded it over his arm. Sans closed his eyes, the aggressive aura he was putting off faded away. When he opened his eyes again the blood red rings had been replaced by a single red dot that looked more like a colorful piece of candy than blood. Just the one, the right eyelight was missing entirely.

Sans had taken his guard completely down, something it would be too dangerous for Gaster to do as well. Instead Gaster moved a few steps up the alley and leaned his back against a wall, head angled to better view the alley's entrance, though he could still clearly see both Sans and the child from the corner of his eye. It's not like he could talk to the child anyway, he may as well keep an eye out for danger.

"what's wrong? why are you crying?" Sans asked gently, his voice achingly soft.

"I'm h-hungry," the child stuttered shyly.

Sans made an annoyed sound. "well that jus' won't do, le's see if we c'n help with that." He made a show of patting down his clothes as if searching for something, then reached behind him to pull out a bag of chisps. Gaster had to suppress a snort, of course he had a bag of junk food in his inventory. He wondered who they had been meant to annoy. "look at that, ya like popato chisps?" Without waiting for a response Sans tossed the bag so it landed just outside the child's hiding spot.

The child snatched the bag up and ripped it open, they grabbed a handful with dirt caked paws and shoved it in their mouth. Sans stayed exactly where he was and patiently watched as the child devoured the whole bag, then started licking up any crumbs they could find.

"feeling a bit better now?"

"Ye-… yeah." The child shifted in their hiding spot, golden eyes darting back and forth from Sans to Gaster. Eventually they let the empty bag fall and pulled their knees up to rest their chin on. "Thank you."

Sans grinned widely, "yer welcome." Silence fell over the alleyway again, the only sound was the child's nervous fidgeting.

"Who are you?"

"i'm sans, and this tall drink of wine is mah hubby, wingdings."

Gaster couldn't hold back a snort at that, a few laughs escaping between the fingers clamped over his teeth. Two sets of eyes were trained on him, to ease the situation Gaster tried to give the child his friendliest smile and a little wave.

"so how 'bout you?"

"I uh… I'm Oliver."

"oliver huh? that's a nice name."

Oliver looked unsure how to react to that, they just stared at Sans.

"oliver, where're yer parents? are ya lost?"

Oliver sniffled loudly and wiped at their nose with the back of a paw. They looked down and away from the two skeletons as they reluctantly said, "They don't w-want me."

Sans scowled, the beginnings of a growl echoing from his rib cage. He put his hands over his face. He took a moment. Then another. Then finally looked back up as his hands fell to his knees, his face a blank mask. "well that ain't right." He turned to look up at Gaster, a silent plea.

Gaster nodded.

Sans turned back to Oliver. "how 'bout ya come home with us instead?"

Oliver looked between them warily. "Really?"

Sans nodded. "yeah, really. your old parents sound like a couple o' assholes, so why not upgrade t' us?"

Gaster stepped forward then, crouching next to Sans. He opened his arms in invitation. He summoned a matching pair of hand shaped bullets, incorporeal in their complete lack of intent. They signed along with his words, "WE PROMISE TO TAKE EXCELLENT CARE OF YOU."

Oliver's brows furrowed at Gaster's incomprehensible speech, eyes watching the hands in confusion. "I don't…"

"he says we'll actu'lly do the job right."

"THAT'S NOT WHAT I SAID."

"eh, i'm off the clock, i aint' gonna translate for ya."

Oliver leaned forward, "Do… do you promise?"

"yeah, we promise."

Gaster nodded his agreement.

Oliver leaned forward until they were about to topple over, eyes searching both their faces for who knew what. Gaster held still despite how his joints were protesting at keeping such an awkward pose for so long. He couldn't help wondering how much pain Sans must be in for staying crouched for so long.

Oliver shot into Gaster's arms, trembling as they hid their face in his shirt. Gaster folded them into a gentle hug, rubbing a hand up and down their back. A wet spot was starting to bloom on Gaster's shirt. Sans laid a gentle hand on Oliver's head and leaned in to whisper quiet promises that Gaster knew they both had every intention of keeping.

Gaster wrapped Sans's coat around Oliver, then shifted his hold to stand up with the child cradled safely in his arms, supported on his hip like he'd seen so many parents do. "LET'S GO HOME THEN, SHALL WE?"

"yeah, let's head on home." Sans slowly stood, his bones creaking and groaning on the way. Without his jacket he chose to shove his hands in his pants pockets and followed Gaster out of the horrible alley he hoped to never see again.

Once home with the door locked safely behind them, Gaster finally relaxed his own protective aura. Oliver looked around them, sniffing the air curiously. Gaster took a moment to look around their living room with a critical eye he'd never needed before. They had nothing in their house for a child. Ah well, that could easily be fixed with a shopping trip in the morning. Still, he had a feeling he'd be spending half the night cleaning and finding new places to keep all their things.

Sans headed straight for the kitchen, where delectable scents were coming from. Gaster followed him in just in time to see Sans lift the lid on the slow cooker he had set going this morning before leaving. The scent intensified, Gaster's soul quivered in anticipation.

"dinner'll be ready inna minute, you two wash up while i finish this." He turned and started rifling through the pots and pans cupboard.

Gaster took Oliver over to the sink and set them on the counter next to it. Fortunately there was a wash cloth right there, he ran some warm water over it, then held out his free hand to Oliver palm up. "YOUR HAND, PLEASE."

Oliver looked unsure, eyes shifting between Gaster's hand and his face a few times, then hesitantly put a paw in Gaster's hand. Gaster took the washcloth and started gently wiping up as much dirt as he could. Once he was satisfied with both paws, Gaster picked Oliver back up and moved them to sit at the table, Red's thick coat still draped over their thin frame. Then Gaster went to help Sans get dinner together.

Sans had just finished portioning freshly made scrambled eggs onto three plates and had moved onto scooping the slow cooker's contents out as well. Gaster grabbed some silverware and the first plate. He set it down in front of Oliver while Sans carried the other two over to their spots.

"bone apatite."

Oliver was already shoveling his food into his face, he seemed to be trying to inhale it. Gaster and Sans let them, eating their own food at a much more moderate pace. Gaster reached under the table and took Sans's free hand, one of the benefits of having opposite dominant hands. He ran his thumb over Sans's knuckles, smiling down at his little husbone.

Sans smiled back up at him, an excited glint in his eyes.

"WE'LL HAVE TO GO SHOPPING TOMORROW," Gaster finally said, the quiet growing too much for him.

Oliver's head snapped up to stare at him, though that did little to slow the fork shoveling more cheesy bacon potatoes and eggs into their mouth.

"oh yeah, we got a shoppin' list a mile long. won't that be fun, oliver?"

Oliver nodded shyly, wilting under the attention. They slowly took another bite.

"but someone'll hafta clear up yer schedule first." Sans looked back up at Gaster.

"SOUNDS LIKE A JOB FOR MY PERSONAL ASSISTANT." Gaster belatedly summoned a pair of bullets to sign, something he was going to have to start remembering to do at home. Though judging from Oliver's blank stare even that wouldn't help much.

"in the mornin', don't think anyone'll answer even if i called anyhow."

Gaster nodded, "BETTER CLEAR UP THE REST OF THE WEEK TOO."

"geez, make me earn my keep why dontcha." Sans grinned and winked at Oliver, who stared at them with wide eyes for the entire exchange. They turned their attention back to their plate, only the last few scraps left.

"ARE YOU STILL HUNGRY? DO YOU WANT MORE?" Gaster wasn't even sure what else they had in the house, but he knew Sans liked to keep a well stocked cupboard.

"maybe not t'night, i think if this li'l guy had any more they'd get sick." Sans reached out and wiped a few crumbs from the corners of Oliver's mouth. Oliver held still, something Gaster wasn't sure if it was a good sign or a bad. They didn't flinch, so Gaster was going to just take it as good and leave it for now. Oliver looked down at their plate and shrugged, eyes drooping, a shy smile peeking out from the corners of their mouth.

"i think someone's ready fer a bath."

Oliver let out a whine, "Do I have to?"

"sorry kiddo, ya need one. you'll feel better afterwards, promise. c'mon, i'll take ya to the bathroom." Sans got up and held a hand out. Oliver reluctantly got up and took Sans's hand, the heavy coat sliding off and getting left behind on the chair. Sans's other hand twitched at his side, like he longed to pick Oliver up and cuddle them close but knew his fragile bones couldn't handle it.

Gaster got up and cleared off the table, he dumped the dishes in the sink for later and gathered up the coat. He followed the other two upstairs, then peeked into the bathroom. Oliver stood next to Sans, still fully clothed while Sans had rolled up his sleeves and undone at least half the buttons on his shirt. Sans had pulled down the shower head and was talking quietly while Oliver listened intently. Gaster left them to it and went to the bedroom to put away Sans's coat.

Oliver didn't have any clean clothes to change into. Something else to go shopping for tomorrow, but that was tomorrow and they needed something to wear tonight. They also needed something to wear while they went shopping tomorrow too, unless Sans expected to put them back in their dirty clothes until they could buy more? Gaster shook his head, one thing at a time. Clothes for tonight, worry about tomorrow when he and Sans could talk about it together. Gaster went to the dresser and started digging through Sans's side. He pulled out the smallest shirt he found, probably would still be a bit large on Oliver but that should be fine to sleep in if nothing else, and it was clean. It would have to do.

Gaster then headed over to the linen closet and dug out the fluffiest towel he could find, then back over to the bathroom. He peeked in, Sans had gotten Oliver out of his dirty clothes and into the tub. Sans had a hand under the faucet as he waited for the water to turn warm. Gaster walked in and dropped the towel and shirt on the counter next to the sink.

"I BROUGHT YOU SOME SUPPLIES, NEED ANYTHING ELSE?"

Sans switched the water to the shower head, then looked over. "oh hey, thanks. didn' even think o' those. think we got ev'rythin' covered here, make sure the extra bedroom's good?"

"AN EXCELLENT IDEA. JUST YELL IF YOU NEED ME." Gaster wanted to stay and help, but he didn't think there was really anything he could help with. Sans was the one who had actually taken care of a child, he would know how to take care of Oliver. The bedroom at least Gaster could take care of.

He went into the disused room, stopping just inside the doorway to take stock. There wasn't much furniture, a bed in one corner with an empty nightstand next to it, an empty dresser in another corner, right next to an equally empty closet. There were a couple boxes that Gaster couldn't quite remember the contents of, but he was sure they weren't suitable for a small child so he moved them downstairs to be looked over and sorted later. While downstairs Gaster grabbed the simplest looking lamp from the living room and moved it to the Oliver's night stand. He looked around again, perhaps it wasn't the best room for a child, but they had an epic shopping trip tomorrow that would hopefully fix that. For now some fresh covers on the bed and pillow and some light dusting would be enough. He hoped. Honestly Gaster had no idea what a child Oliver's age would even want or need. Or even more than a vague idea of how old Oliver even was. Old enough to have started school… probably.

"and this here's yer new room. ain't much t' look at yet, but we'll take care o' that t'morrow. heh, placed used t' be mine, back when i first moved in wi' dings."

Oliver was looking around curiously, orange fur fluffed up from its recent washing and drying. They looked much more awake than they had after eating, weren't baths supposed to soothe children? Well, perhaps not kittens. Gaster would have to ask Sans about it later, he'd have a lot to ask Sans about later.

The bed was perhaps a little too tall for someone even shorter than Sans, Gaster picked Oliver up and sat them on the bed. Between Sans tugging the blankets back and Oliver scrambling over them they soon had Oliver laying in bed with Sans tucking them snugly in. It was actually quite fascinating to watch, like they'd both done this a thousand times before. Gaster supposed they had, just never with each other.

Sans gave the bed one more pat. "so… ya want a bedtime story?"

Oliver's eyes grew wide, practically glowing with happy little sparkles. "Can I really?"

Sans laughed gently. "'course, wouldn't'a offered if i hadn't meant it." Sans sat on the edge of the bed, angling himself so he was facing Oliver the best anyone could in such a position. "now, we don't got any story books yet," something else Gaster added to the ever growing mental list of things to buy, though knowing Sans he already had one twice as long and far more comprehensive, "but i do know a story ya might like."

Gaster hovered near the door, unsure if he should stay or go. Oliver looked up at him, seemingly equally unsure about Gaster's presence. Sans paused, following Oliver's line of sight, then patted the bed next to him.

"come join us."

"ARE YOU SURE?"

"what's with ev'ryone askin' me if i'm sure? yes! come sit."

Gaster obediently sat, then scooted closer and happily gathered Sans into his lap. Sans just as happily leaned into him, settling in to start the story.

"Once upon a time, there were two orphaned brothers."

Gaster sucked in a breath, both in surprise at Sans using his 'translator mode' voice and in recognition of just what story he was about to tell Oliver.

"The world is cruel and life was hard for the brothers, but the older one was determined to take care of the younger one. They were the only family either had in the whole world, the older brother wasn't going to just abandon the younger brother. It was hard and they never had much, but the older brother made sure to give the best of what they had to the younger brother. What little food they had he gave to the younger, even if the older had to go hungry. What little clothes they had went to the younger, even while the older's grew too small and ragged. What few toys they had went to the younger, even though the older hadn't had a toy of his own since their parents died.

"And then one day they were both finally grown. The older brother celebrated, it had been a long road but he felt he had accomplished something. They were both alive and well, they had a home, they had food in their cupboard, they had clothes and books and everything they needed. And now that the younger brother was grown and could get a job the older brother thought it was time to start sharing responsibilities, to maybe not work quite so hard all the time anymore.

"But the younger brother took his first paycheck and bought himself all the things he had always wanted but could never have. The older brother didn't mind, he felt bad that he couldn't give his younger brother those things when they were children and told him that his happiness was more important than a few bills the older brother could pay on his own. But things continued in this way. First the younger brother never spent his own money on things they needed, then he started taking what little gold the older brother had left after paying for what they needed, then he started leaving all the chores for his older brother, then he started taking away his older brother's things. Pretty soon the older brother was back to wearing rags and working for his younger brother like his slave. All the neighbors forgot they were brothers at all and started treating him like he was a slave."

Gaster wrapped his arms tightly around Sans, he didn't even want to know what memories this story was surely bringing up.

"And then one day the older brother met a prince."

"A PRINCE?!" Gaster asked in surprise.

"King Asgore's son? Prince Asriel?" Oliver asked curiously, head tilted at an odd angle.

Sans chuckled, "not quite, a diff'rent kinda prince. a story prince, stories're always fulla princes an' princesses flouncing around doin' who knows what. anyway," Sans took a deep breath.

"Once upon a time there was a prince who had been cursed at birth, no one could understand a word he said."

Oliver's eyes snapped to Gaster, sudden realization dawning in them.

"He hated it, he hated that no one ever listened to him and he hated that no one ever even tried, so he moved into an Ivory Tower an-"

Gaster burst into wild laughter, he hid his face by pressing it to Sans's skull and hugged his husband tight as he tried to get himself under control. Sans patiently waited for him to calm down before continuing.

"What? What's so funny?" Oliver asked.

"don' mind him, he jus' knows the story, i'm uh… takin' some liberties with it." Gaster could feel Sans wink at Oliver.

"What's a 'vory tower anyway?"

"ivory, it's uh…" Sans stalled, drawing out the 'uh' until he leaned back and tilted his head despite Gaster still hiding his face in his skull. "babe, what even is ivory?"

"IT'S MADE FROM A SPECIAL KIND OF TOOTH, I BELIEVE."

"it's teeth?!"

"Teeth? Really?"

"VERY LARGE TEETH THAT BELONG TO VERY LARGE SURFACE ANIMALS."

"big ol' teeth from big ol' surface animals. that's badass."

From the way Oliver was running a claw over their own teeth and smiling wide, Gaster was fairly certain they agreed.

"ok, ok… where was i? ivory tower, right? Okay. The prince moved to the top of the Ivory Tower, becoming the prince of the Ivory Tower. One day, on his way to a visit with the king, he bumped into a mere commoner dressed in rags, the older brother from the first half of the story. Of course the brother was just a commoner, so the prince wasn't wrong. The prince was annoyed at the delay and called the commoner a very rude name."

Gaster tried not to take offense, Sans was taking quite a few liberties with the story, leaving a great deal of detail out. This was perhaps the best way to tell it without all those missing details, it still annoyed him that 'the prince' was being portrayed like that.

"Recognizing the prince, the commoner of course bowed and apologized. The prince was amazed, the commoner had understood him! So rather than run off to his visit with the king, the prince stayed and talked to the commoner.

"The commoner didn't actually understand the prince, he was just trying to be polite. But since the prince was still talking to him, the commoner of course paid attention to him, he couldn't afford to be rude after all. At first he had to guess what the prince was saying by paying attention to the way he moved and the tone of his voice. But the more the prince spoke the more the commoner realized that there was a pattern, that the prince was just speaking in a code. The more he listened, the easier it became to understand the prince, until they were both talking easily.

"And then the commoner's younger brother came along and scolded him for taking so long to run his errands. The prince realized just how late he was and rushed off to go talk to the king about the Ivory Tower. But the prince didn't just forget the commoner, he couldn't stop thinking about him. So the prince went and searched far and wide until he met the commoner again. The prince confessed his love and asked the commoner to marry him. The commoner was so surprised and so flattered he started crying."

"Why would he cry?" Oliver asked, voice sounding genuinely distressed.

"Because the commoner had fallen in love with the prince too, but he thought they would never meet again. He spent all the time the prince was searching for him being sad, but he couldn't cry it out then so instead he bottled all his sadness up. He had to cry it out before he could feel all the happiness from being reunited. So the prince carried the commoner away and they were married and the commoner never had to be a slave again."

"And they lived happily ever after?"

Sans hummed in thought, "Not quite. You see, the prince was very old, it had taken a long, long, long time for him to meet the commoner who would become his husband. The husband wasn't much better, he was weak and sickly from all the years of being poor followed by even more years of being a slave. They were too old and broken to have children of their own."

Gaster squeezed Sans tight again, biting back a reprimand about how much he hated it when Sans talked about himself like that. It would only frighten Oliver and make Sans defensive.

"Even without children they were still very happy together, and for a while that was enough. Then one day on their way home from another visit with the king and his court, the prince and his husband met a small child, a street urchin that had been abandoned by their asshole parents. The prince and his husband loved the child the moment they met, so they took them home with them. Together the three of them finally got their happily ever after."