Okay, so he would be the first to admit this hadn't been a good idea. At all. Ever.
Gaster had honestly been surprised at how… tranquil the void was. At first he'd been expecting shadow beasts to come and grind his bones or an infinite blackness that would make him desperately insane. Instead, there was just… a grey room. He had no idea how big it was, as there were seemingly no walls or points of reference. But there was a floor underneath his feet and a white sky over his head, so at least he had that.
After a while (he had no idea how long, time wasn't really a thing in the void, it seemed) he'd found the 'Control Panel'. Truthfully, Gaster had no idea what the phenomenon was, even with all his scientific knowledge. One day, after a fitful nap it had just… appeared. It wasn't anything physical. More like a set of floating neon blue holograms. It was fascinating to say the least and definitely more interesting than anything else in the void. So, he'd played around with it.
There'd only been small changes at first. Well, small being a relative term. After a few button clicks the void was no longer a grey room with a white sky, but a peaceful, sunny meadow, like the ones Gaster had seen before the war and in human picture books. Above him the sun, and sometimes the moon, glowed. It was a definite step-up and it only encouraged him to continue fiddling with the menus and options written in a language that even he had trouble deciphering.
His second big discovery had been what he termed 'The Reel'. 'The Reel' was just that. An old film reel like the ones monsters had occasionally salvaged from the junk-piles that cascaded down Waterfall. However, instead of a clunky physical interface, the Reel simply unfolded like another set of menus, expanding across Gaster's field of view. Each one depicted a different scene, sometimes ones he recognized, sometimes ones he could never imagine. In some, he was still 'alive', playing with his sons and their friends. In others he saw them living in space, or in the human world. Sometimes they were monsters, other times humans. It was an endless amount of possibilities and, though it was improbable, Gaster had concluded these must be other universes, timelines that played out in hundreds of thousands of different ways.
Two caught his immediate attention. The first was in the Underground, exactly as Gaster remembered it. Everything was the same… except the monsters. From what Gaster could gather, each of the monsters he remembered seemed to have switched with one another. Papyrus was laid-back, wearing an orange hoodie and constantly falling asleep. Meanwhile, Sans was energetic and heroic, hustling from place to place shouting about puzzles and becoming a member of the royal guard. Despite the switches, this universe seemed bright and cheerful. Threats still existed in the form of a demented Temmie-type creature, but everything else seemed fine.
The other was the exact opposite. Everyone was in their same roles, but twisted with such evil that Gaster could barely recognize any of his former friends and family. Here, Papyrus was a member of the Royal Guard. In fact, he was the captain. But he was far from his jovial self. In fact, he was a cruel monster, always fighting or killing or demeaning others. Even his own brother. Sans, his poor son, had been demeaned to the level of a minion and manservant.
Gaster's broken soul ached for his two sons, who had to deal with living in such a dangerous world and that they couldn't live in peace as they did in the former universe. So, determined, he'd set out to change it.
And this was what had gotten him into his particular predicament. He'd been swiping furiously at the menus, tapping various buttons and flicking switches, checking for changes. Seemingly, nothing had changed. That was until he'd opened a portal. And the Sans from the cruel universe had been sucked in. And he didn't know how to undo it. And he didn't know where he'd gone.
Was it possible for a void-being to get fired?
"YOU USELESS SACK OF BONES!" Papyrus roared, red eyes burning. He glared down at his older brother, who was struggling not to tremble in his sneakers and failing miserably.
"S-sorry, B-boss…" Sans rubbed his clammy skeletal hands together in nervous habit. He glanced up at Captain Papyrus, but quickly flicked his skull back down when their glowing eyes met.
"SORRY?!" Papyrus spit out the word contemptuously, causing Sans to twitch like the word had physically hurt him. "YOU THINK 'SORRY' IS GOING TO FIX THIS!?" He growled low, eyes flaring before he spun around on one booted heel in the snow of Snowdin Forest and stepped away, shouting as he went. "I MEAN, YOU'RE ALWAYS SO PITFULLY WEAK AND USELESS! BUT THIS REALLY IS THE CHERRY ON TOP! HOW IN ASGORE'S NAME COULD YOU LET A HUMAN GET PAST YOU!?" Papyrus turned again, observing the pitiful figure of his brother. His brother had always been short, a fact that did nothing to help Papyrus' opinion of him. At the moment though, he seemed even smaller, his shoulders hunched towards his ribs, curling in on himself to try and take up an even smaller amount of space than he already did. Sweat rolled down his skull, occasionally congealing in the crack that ran down from the crown of his skull and past his right eye-socket, where trembling red dots stared resolutely at the ground. He was weak. So very weak.
And Papyrus hated that.
"B-boss! I-i!..." Sans tried to speak, his voice trembling as it always did when he was nervous. Which was almost always. Papyrus hated that too.
It really wasn't his fault! Really! It wasn't like he'd meant for the human to escape!
Sans' mind raced as he tried to find some way to explain it so that he wouldn't get hit again. It was proving to be an impossible task. The start was innocent enough. He'd been at his sentry station, keeping a careful watch on the traps for any sign of human activity. Definitely not sleeping.
Then, suddenly, from out of the blue, he was woken up- I mean surprise attacked by a human. Of course, he was ready to go to battle immediately. But that stupid human and that stupid asshole talking plant friend of his had tricked him. Yeah, that was it! No, wait…
Wait, yeah. It had been a… tactical decision!
"B-boss. They… um… they had a secret power!" Sans blurted out, quickly covering his teeth with his hands. That just sounded like an excuse. Sans braced for the punch, but instead was met by a quirked eye-ridge. Sans breathed an internal sigh of relief. Good, he'd piqued his interest. He continued, gesticulating wildly with his arms. "Yeah! T-they could… their words had power, boss! They…uhmm… hypnotized me!" He studied Papyrus' expression, relieved it hadn't changed from minute curiosity. "They had potions too! Poison! They and their partner shoved it down my throat and it knocked me right out! I tried to fight them, but… t-the poison was too strong…" Sans took a deep, shuddering breath. Maybe he'd get out of this without a new bruise. Or at least, a new scar. "I… I called you as soon as I woke up!"
Sans, at the end of his explanation, stopped, arms dropping to his sides before hunching inwards again, waiting for his judgement. He carefully, but subtly, observed the minute changes in Papyrus' expression. His red eye glared down at him, never changing their focus. They seemed to burn holes right through Sans soul, going straight through his half-assed lies. Sans fought not to tremble uncontrollably, though he couldn't stop his nervous twitches. Papyrus' fanged mandible was moving slightly, as if chewing on the words he was about to say.
A second passed. Two. Three. Then Papyrus opened his jaw, sucking in air.
"That is… satisfactory." Sans couldn't help but sigh, his shoulder slumping down as he momentarily relaxed. "We should keep an eye on this human… if what you say is true-" his eyes flared at Sans, causing him to instantly tense again. "-then we may need to exercise a certain degree of caution."
Papyrus advanced towards Sans, his long stride closing the distance between them in moments. Sans tensed even more, if such a thing were possible, straightening his spin on instinct and presenting himself like a soldier before his commander. Papyrus leaned down so his skull was level with Sans', forcing Sans to look directly into his brother's menacing eyes.
Aeons seemed to pass, Sans frozen in place by Papyrus; soul-searching stare. The silence was deafening and Sans could feel the beating of his soul in his skull, responding to his distress. Shit, what was he going to do?!
Suddenly, Papyrus nodded, humming as he started to draw himself back up. Sans was about to relax when a glowed palm swung at his face, slapping his right cheek-bone. Hard. So hard that Sans was thrown from his feet-
THUD!
-flying into the trunk of the nearest pine-tree. Sans' back hit the tree full-force, knocking the air from his frame in a painful gasp. His soul screamed in pain. He slid down the trunk, collapsing into the snow where he curled into a ball, hot tears streaming down his cold face.
"OH, STOP CRYING YOU WASTE OF SPACE." Papyrus turned, dismissively waving at Sans. "NOW GET OUT OF MY SIGHT. YOU BETTER NOT COME BACK HOME TONIGHT IF YOU KNOW WHAT'S GOOD FOR YOU EITHER." And he walked away, back towards Snowdin.
When he was gone, Sans let out a loud, gross sob, trembles overcoming his whole body. He clamped his mandible shut, choking the next sob before he embarrassed himself further. He tried to move, hissing when he moved his spine. Another bruise would promptly be forming, he knew. However, there wasn't any permanent damage. So, battling through the searing pain, he stumbled onto his feet, steadying himself against the tree. He took shallow breathes to avoid irritating his injured spine and limped slowly away from Snowdin, deeper into the forest.
As he made his way deeper into the foliage, the surrounding area became darker, the light of the roof-crystals blocked out. Normally, doing something like this was a death wish, as areas like this were a favourite for monster-killers. But Sans didn't care. In fact, he welcomed being dusted. Then he wouldn't have to deal with this shit anymore. He wouldn't have to deal with the verbal abuse from his brother. Or the physical abuse of all the other monsters. Or the fact that he knew he would one day be killed and no-one would even give a damn. He just wanted to leave it all behind.
Sans stumbled on a tree-root, falling to the snowy floor. He didn't get up. He was just so tired. Tired of being mistreated. Tired of being abused. Tired of no-one caring about him. Just… tired in general. His health had never been great and he was indubitably the weakest of all monsters in the Underground. He chuckled bitterly to himself as he lay in the snow, letting the frigid cold bite into his bones. Yeah, even the kids were stronger than him. How pathetic was that? His chuckles turned to sobs and he shook helplessly on the ground. Yeah, he should just die.
Die.
Die.
Die.
Die.
A loud whooshing sound, distracting him away from his self-hatred.
"Huh?" He lifted his skull from the snow, glaring forwards. He'd expected to see a monster poised to finish him off. Instead, however, was met with a semi-solid blue mass, which undulated like water floating in the air. Sans' pupils contracted. That was new.
He had already begun to crawl backwards, instinct driving him to flee. But the mass didn't seem to like that and instead of going backwards, Sans felt himself start to be sucked forwards, carried by an unexplainable gale. Sans was lifted from the floor and he was forced to grab a stray branch to stop himself sailing straight into the mass. Was this some new monster ability or something!?
"Agh!"
He kept holding onto the branch, feeling it bend as the force of the sucking increased, taking snow and rocks and twigs from the surrounding area into the mass.
"Shit! Come on!"
Sans grabbed the branch with two hands now, gripping as hard as he could. He didn't want to die. Not like this! He tried to climb along the branch to get to safer ground. One hand forward, then another. The force of the pull was only getting stronger. But Sans was determined. If there had been anything he was decent at it was surviving all the shit that got thrown at him. Somehow.
"Come on you useless bag of bones! Work those lazy arms!" He shouted at himself, unable to hear it over the sound of the mass behind him. He was doing it. He'd progressed to over the halfway point now and ever closer to the trunk of the tree. If he could just get behind the trunk, the mass probably wouldn't be able to get him. Sans grinned despite himself. If there was a time to prove his brother wrong, it was now.
His hope was promptly snapped in two as the branch he was inching along did the same, splintering and sending his careening into the mass.
That's it, he thought as a blue light engulfed him, this is how I die.
Papyrus yawned loudly, humming in satisfaction when his bones popped from being stretched over his head. He put his hands in the front-pocket of his hoodie, fumbling around until he found a lollipop in the mess of old wrappers and cigarettes. He pulled it, throwing off the wrapping with a practiced movement, throwing the wrapper behind him as he stuck it in-between his jaws.
From behind him, he heard a little humph and the crinkle of the wrapper as someone caught it. Papyrus smiled to himself, turning his skull slowly around and down.
He spoke around the lollipop. "oh hey bro…didn't see you there." Sans glared up at him, his mandible set into a pout and his white pupils glaring disapprovingly at him.
"WHAT DO YOU MEAN YOU DIDN'T 'SEE ME'!?" He exclaimed, throwing his arms up in the air. "THE GREAT AND MAGNIFICENT SANS HAS BEEN FOLLOWING YOU ALL MORNING!" He pointed accusingly at the wrapper. "AND DON'T LITTER, I HAVE ENOUGH JOBS TO DO WITHOUT YOUR BOONDOGGLING!"
Papyrus nodded, trying to look suitably repentant, though he knew it would come out as nothing more than a lazy smile.
"sorry bro. won't happen again." He reached out his arm, grabbing the wrapper from his brother phalanges and shoving it, with all the other trash, into his hoodie pocket. He needed to restock on 'pops soon.
"IT BETTER NOT!" Sans exclaimed, pouting for a bit longer before his permanent smile took hold again.
"anyway," Papyrus continued as they walked down the path in Snowdin forest, "why in asgore's name did you wake me up so early? it's still a good hour before our shifts…"
Sans looked offended, his nasal aperture flaring. "LANGUAGE, PAPY! AND IT NEVER HURTS TO BE ENTHUSIASTIC!"
"but haven't we already let the kid pass? isn't this kind of pointless now?" Papyrus retorted, raising one long phalange into the air to empathise his point. Sans obviously hadn't expected that question, because for a moment he stayed completely silent, which only happened when he had to think hard about something. After a moment, Papyrus heard a loud 'ahah!' and Sans ran in front of him, stopping him.
"OF COURSE! BUT I HAVE A FEELING!" Papyrus tilted his skull, eye-ridges rising.
"a feeling?" He chuckled. It was an old trick of Sans to excuse any illogical behaviour with him saying he had a 'feeling'. Of course, Papyrus wasn't the type to believe in metaphysical stuff like that. It was probably more out of habit that his brother had dragged him here. It wasn't like he minded though. "again? what sort of feeling is it this time bro?" Sans puffed out his chest, his blue bandana waving dramatically around his battle body.
"A FEELING SOMETHING DRAMATIC WILL HAPPEN IN THIS! EXACT! SPOT!" Sans dragged his snow-bots along the floor, creating a small 'x'. Papyrus' eye-sockets widened slightly in mock amazement.
"really? here?"
"YES, HERE! MWHEHEH! AND THE MAGNIFICENT SANS WILL BE THE FIRST TO WITNESS IT!" Papyrus gasped, putting a hand to his skull and making to swoon.
"and you trusted me to be your companion? i'm truly honoured."
"MWEHEHEH! I'M GLAD TO SEE YOU'RE TAKING THIS SERIOUSLY FOR ONCE, PAPY!" Sans laughed long and loud, striking a heroic pose which looked somewhat hilarious considering his short stature. Sans spun on his heel, facing deeper into the forest. "NOW, ALL WE HAVE TO DO IS WAI-"
Suddenly, a loud whooshing noise came from in front of them. Sans jumped back with an undignified yelp, jumping straight into Papyrus who's eyes were widened for real now, pupils contracted and bones tense. That was new.
Out of the blue shimmering mass, snow started to pile up, spreading out across the patch. When it seemed like the mass was done, it threw out a small black and white ball, flinging it into the snow. Having dropped its load, the mass flashed away as quickly as it'd appeared.
A deathly silence settled over the pair.
"what was…" Papyrus started, Sans slowly advancing towards the snowdrift where the black and white ball was curled up. Papyrus watched him carefully, making sure he was in no imminent danger.
"OH MY STARS!" Sans exclaimed, running towards the huddle ball and glancing urgently at Papyrus. "PAP! QUICK! IT'S A MONSTER!"
A monster…? That was definitely new. Papyrus hustled to the snow drift, looking down at his brother who was on his knees, staring at the white and black ball. As Papyrus got closer, he saw the ball wasn't a ball at all. It was indeed a monster.
"…Urgh…" the monster groaned and Sans and Papyrus both twitched. The monster's voice sounded faintly familiar. "What… how am I… ow."
The monster uncurled from the ball-shape it had drawn itself into, revealing the black was from a jacket and shorts. When they saw the monster's face, they were both too shocked for words. Well, at least Sans was.
"well, damn." Papyrus said, the lollipop falling to the floor.
And this time, Sans didn't correct him.