Premise: What if Sans had fallen into the Core instead of Gaster?

Not everything is as it seems in this fic, as we go along, I would love to know what you think and theorize!


Gaster could not think of a time when the days went by so slowly. When he bothered to check, it seemed only minutes had passed when it had felt like hours. At some point he realized full days could have gone by and he simply hadn't noticed. He could not bring himself to care enough to find out. For himself, moving felt like he was trudging through thick sludge. The effort was too much, and so eventually, he wasn't sure after how long, he just stopped.

No one remembered. No one even realized something had gone wrong in his labs. Only days ago, five brilliant monsters disappeared. Sans had disappeared, and not a soul recalled who they were. When Gaster realized it he was lost. He could not return to the lab, he could hardly leave his own room.

Papyrus still brought food to him. Simple meals he could put together without the need of their tiny stove, which he knew not to use on his own. The boy would sit on the floor and chatter away, not asking questions or prodding him. He only sat and talked, and Gaster let him, but he didn't quite hear. Papyrus didn't know his own brother, and the daily updates from his youngest son only made his heart ache worse for the loss.

Day by day Papyrus would come in, his monologues shortening each time, until he was simply delivering a plate and leaving again. He was too young to understand, how could Gaster explain what had happened? Who would even believe it?

The scientist wracked his brain for anything, some idea for how he could get them back. The desk in his room became littered with scribbled on papers, empty ink wells and broken and dried out pencils and pens. Sans had always told him he could get carried away before. It was an old madness he allowed to overcome him as he was shutting everything else out.

Yet despite the endless ideas, figures and calculations, nothing came to close. No theory followed through and no plan could be realized. The determination he had fell into despair again, and weariness took over. After the second day without accepting one of his meals, Papyrus began to sit with him again. He asked only once what was wrong.

"The world is dark," was his reply. After that, Papyrus remained quiet.

At some point the boy had mentioned that the light never showed in his working eye anymore. He should eat, he should go out, he should do something.

"Can you speak?" young Papyrus had asked once, voice hardly above a whisper. "Did I do something wrong?"

"No," Gaster replied. "It was all me."

He didn't speak again, instead drifting into the blankness of sleep. Even there he received no solace from his anguish. When he woke again, Papyrus wasn't there, and he didn't return.

Sans had been a watchful big brother. Gaster had not been neglectful to either of them, but when he was busy with work, Sans took on much of the responsibility of taking care of the youngest. Papyrus usually trailed after him, wanting to play, work on puzzles or be read to. Sans never disappointed. The brothers were extremely close, but Gaster still knew how Papyrus was. When his youngest son didn't come back that evening, urging him to eat, the adult took notice.

Maybe he's lost track of the time. It would be a first, but not unheard of. Perhaps they'd even run out of food by now? But surely Papyrus would have said something about it if they had. Had he?

How much time had even passed? Did Papyrus know where to go for more supplies? Did he even know where their gold was? Gaster struggled to sit up. He should check. His body shook at the effort. When was the last time he'd eaten?

His voice cracked, barely forming his son's name. There was no answer.

Maybe Papyrus had given up on him? Pitiful as he felt, he almost didn't doubt it. Except Papyrus didn't give up. Not like his father. Gaster curled in on himself, trembling, weak, and anguished. If Papyrus remembered anything, would he give up like he had?

Not if Gaster were still there.

The scientist weakly gripped the edge of his mattress, pulling himself forward. Legs inched over the side of the bed, but he couldn't lift his body up. Blackness edged his vision, and he couldn't tell how far he had moved until he fell off the mattress onto the floor. Jarred, Gaster lay still, gasping. For how long had he been in this state? A shaking hand lifted and he held it before his working eye. His vision was tunneled and blurry, but he struggled still, determined. He still had a son to care for. Slowly, the hand fell, and before everything blackened completely he thought he heard a knock.


Papyrus had only visited his father's lab once. The reason why escaped him, but he remembered being excited about seeing the workspace. It was important to his dad and...someone else. It was important to everyone, he'd been told. Dad was the royal scientist. He was working on ways to help monsters.

"He's the hope of all of monster-kind!" he'd heard before. He wasn't sure who had told him.

Something happened though. His father hadn't gone to his lab for a long time, and had even stopped working on anything at home. Papyrus had seen some of the papers in his room, but he didn't understand most of it, the notes seeming nonsensical to him. He couldn't think of what had bothered Dad so much. He wasn't hurt, but he wouldn't move, and Papyrus could no longer get him to eat either. Fearfully, the boy decided he needed to find help. He managed to find some gold in their home, and brought some fresh food home, something that didn't require much effort to prepare, and left it out and ready for Gaster if he left his room. Then the young skeleton went out alone, hoping he correctly recalled the way to the lab.

He couldn't remember the names of anyone his dad worked with, but didn't think about it for too long. Someone should be there, someone who knew his dad and would help. He was sure of it.

Their home sat just outside of the Capital, in Hotland. Anywhere the young skeleton normally went was usually towards the more crowded streets of the city. The schools, markets, and shops were all situated in the Capital. Papyrus followed the quieter path away from the city. On a few occasions he had travelled this way with his father for a trip to another part of the underground. Sometimes they took a riverboat, and he was sure the lab was close by where it docked.

He walked slowly, feeling guilty. He was old enough to go out on his own if he wasn't going far, but Hotland wasn't as safe as the Capital, and Dad didn't like him wandering the narrow paths alone. Papyrus stayed attentive as he went. For many days now he'd done a lot of things on his own. He didn't mind it really, he wanted to help. Dad was upset about something, if he could make it easier at all, he would. The older skeleton had said Papyrus wasn't the cause of his sudden depressive state, but the boy couldn't understand what had happened.

Something certainly felt strange, like something was missing. Maybe someone had upset his dad, or maybe an experiment had gone wrong? Whatever it was, Papyrus felt like he should know about it. Somehow he felt like the only ones who could help would be found in the lab, as well as the answer to what caused the change in his father.

The farther he walked, the hotter it felt, and he became very glad he didn't have to travel this far regularly. How did Dad manage it all the time? Still he kept going, only slightly disappointed that the puzzles along the way had been deactivated. They would have slowed him down anyway. He wished the conveyor belts had been shut down as well. Grateful as he was for the time that was shaved off of his journey, the quick movement made him feel ill, and he moved a bit slower afterwards until he saw the large white building ahead.

Relief washed away the sick feeling, and he broke into a run, eager to get out of the heat. The image of his father lying in bed as if he'd lost all hope drove him even faster, until he was feet from the large doorway. Papyrus swallowed, worry having built up inside him again as he stood staring at the entrance. Someone here would help right? Even if something bad happened, the people who worked here would want to make sure his dad was ok. They were all working to save everyone...

Unsure, he knocked on the door first. When no answer came, he knocked again, and pressed his skull to the metal, listening. There was no sound. A minute passed before he hesitantly tried the door. It gave, and he entered cautiously. The room was dark and quiet; only a muffled whirring sound came from far away. He ran a hand along the closest wall, hoping to find some switch to light the area. He felt none, and continued forward, keeping his hand on the wall as he went.

"Hello?" he called out. Only the whirring answered. As his eyes adjusted to the dark, he noticed the glow of white light coming from a distant doorway. Refusing the thought of turning back, Papyrus quickened his pace slightly, clenching his teeth hard in anticipation. His hand fell off the wall onto the door and it pushed open easily, opening to a hallway. The soft light made it so he could see the faint outlines of just a couple doors on either side, before the floor gave way to stairs leading down to some lower floors. The young skeleton inched his way about halfway down the short hall, glancing around with wide eye sockets. The light had no source that he could see. The area was simply illuminated, and the longer he stood there, the more unsettled Papyrus became. He shifted his weight anxiously, trying to decide between exploring further or checking the rooms behind the doors. The thought to turn back popped up again, making his soul thrum with nervous energy, but he pushed it away again. Steeling himself, he reached out to the first door on his left, then froze. A crackling sound echoed around him, originating from below. It was haunting, like a whisper, but full of energy. Papyrus jumped at it, and barely restrained a yelp of fear. Hand still hovering in the air, he stared at the top of the stairs, expecting someone to appear there, anything to explain the sound. Nothing changed, and without quite realizing, he took several steps forward, peering down the steps.

The crackling sounded again, not as loudly, beckoning him. Whether out of curiosity or some other force, he wasn't sure, but the boy moved, slowly following the stairs down, around, and down again, until he faced a longer hall, lit the same as the one above, and lined with more doors on either side.

Nameplates hung beside each door, labeling them, but Papyrus ignored them, continuing his trek as if on autopilot.

There was one open door; the last on the right. Papyrus stopped just before reaching it, leaning forward to poke his head inside.

"pap, what are you doing here buddy?" laughed a voice. "did the sitter bring you by?"

"I wanted to surprise you…" Papyrus said quietly, unconsciously.

The small room was dimly lit with the same eerie glow that filled the halls. Cluttered counters lined walls that weren't covered with tall bookshelves. Papers, both crumbled and lying in neat piles made up most of the mess, but tools and supplies of various uses also lay around in no discernable order. A wheeled chair lay knocked over near the center of the room, and another stood upright in front of one of the overfull bookshelves. To one side of the doorway was a line of coat hooks. Hanging on it was the familiar white lab coat belonging to his father, and just next to it a hooded jacket. No one was inside.

The skeleton made no move to go any further into the room, instead he backed away from the doorway, feeling suddenly wary of the place. Apprehension fell over him, making his soul flutter in his rib cage. Again the crackling sound echoed around him, and he spun, fearfully looking for what had caused it.

"HELLO?" he called, louder and more shaky than he'd wanted. "IS ANYONE HERE?"

Papyrus pulled his arms close to his chest, eyes darting around, waiting for an answer. None came. Shaking, he sunk down to the floor. Papyrus called for help.

But nobody…

"papyrus..."


It was not very often that Papyrus met new monsters. Not that he already knew everyone in the underground, though he wouldn't mind it. He rarely went farther than Waterfall where he met with Undyne, and not many new monsters traveled as far as Snowdin from Hotland or New Home. Never had he seen a traveller come from the ruins before. He didn't know of any monsters that lived behind the large door, and the only reason he went this far was to check for fallen humans that managed to get through. Humans were the only ones that came from the ruins.

He'd never seen a human before. Papyrus did vaguely understand what they were supposed to look like, but he was sure they were not supposed to be this small. The person standing before him barely went above his knee in height. They stared up at him, mouth hung open slightly and hugging their own thin frame against a gust of wind that blew passed. Their puffy striped sweater the only defence against the chill.

The tall skeleton stared back at them, trying to decide what to do next. If it was in fact a human, he was meant to capture them and deliver them to Undyne, but as he watched the small person shiver, his instincts told him to take them home instead, and make sure they got warmed up.

"Excuse me!" he called, making sure his voice carried as they were still at some distance. "Are you a human?"

The creature stood still for a moment, only slightly tilting their head to the side as they watched him. They seemed to come to a decision finally, nodding to him with a small smile.

"I see…" he called. A human, a REAL human. Excitement billowed up within him as the information sunk in. With a human, he could finally join the Royal Guard. He would get the respect and recognition he'd been working towards. His dreams could be realized!

He chuckled to himself, his signature "Nyeh!" growing louder until he could not contain it any longer. His legs spread into a practiced pose, his hand lifting to point at the child who took a small step back, looking bemused.

"HUMAN!" he said powerfully. "I, THE GREAT PAPYRUS, HAVE BEEN PREPARING FOR YOUR ARRIVAL! WITH YOU CAPTURED, I WILL JOIN THE ESTEEMED RANKS OF THE ROYAL GUARD AND FINALLY MY POTENTIAL WILL BE REALIZED! PREPARE YOURSELF HUMAN! FOR BEYOND THIS POINTS AWAITS FOR YOU MANY PERILS OF MY CREATION! PUZZLES! JAPES! NYEHEH! I EXPECT YOU WILL BE A WORTHY OPPONENT, BUT THE GREAT PAPYRUS WILL NOT LOSE TO YOU!"

His speech complete, Papyrus turned and dashed to his closest puzzle trap, leaving the confused human behind. Once out of their sight, and nearing his first trap, he slowed, feeling his bones rattle with anticipation. Today would be the day he would show everyone just how great he was.

Papyrus was getting frustrated. The human was easily making it passed his puzzles. Rather than getting stuck, they seemed very determined, and also like they were having fun. This delighted the skeleton. He had no idea his puzzles could bring such joy! But one puzzle was malfunctioning.

"PLEASE BE PATIENT HUMAN!" he called to where they were standing in the middle of the tiled platform. "THE MACHINE SEEMS TO BE BROKEN. I WILL ATTEMPT TO CORRECT THIS SO WE CAN CONTINUE!"

The human just nodded, flashing him a little smile, before looking down anxiously at the tiles around them.

Papyrus glared at the machine that controlled the platform. It was meant to randomly generate a path with different obstacles for the human to make it through. When he turned it on however, the entire platform turned pink, allowing the human to move freely. This alone was annoying, as there simply was no challenge for the human, but then it changed. The human stepped tentatively across the platform, and when they were halfway across, the tiles around the one they stood on turned red, preventing them from moving another inch in any direction. They were trapped.

Well it wasn't a terrible turn of events, Papyrus needed to capture them after all. However the skeleton wondered if the machine would change again on it's own. If it did, it could be very dangerous. The idea was all too worrying.

He grumbled to himself, unsure what to do. Doctor Alphys had created this machine, what could he do to stop it? Looking over the panel of buttons he almost slapped himself. Of course! There was a power switch. He quickly flipped it, grinning proudly.

A long beep sounded, and behind him the human let out a distressed yelp. Papyrus spun around to look at them.

Instead of turning blank, the floor had changed again. Around them, the tiles remained red, but the tile under the human had shifted to blue, then turned to water. They dropped, the water coming up to their waist. In another instant, the outermost tiles all turned yellow. Electricity.

A bead of sweat appeared on his skull as he watched the human hug themselves, nervously eyeing the line of yellow that crackled around them. Another long beep made them both jump, and the circle of yellow closed in by one. The human stared at him, fear clear on their face. Papyrus whined in panic and turned away again.

"Stupid machine!" he muttered, tugging at the panel of buttons. It didn't budge, and Papyrus's mind raced with the sound of crackling energy behind him. He stared at the machine, frantically looking for some wire to disconnect or weakness he could take advantage of. There was nothing.

He spun around again at yet another long tone, and now only the circle of red separated the human from the electric tiles. If the red turned to yellow, it would electrify the water they trembled in. He clicked his teeth together, making a decision.

He summoned a bone attack, lining up several femurs in the air parallel to each other and feet apart. They lined up over the sparking platform, the last one hovering over the human. He stepped up onto the first, sure of their steadiness, and bounded up, using each bone as a step.

"HUMAN!" he called when he was over them. He reached down carefully, keeping his balance. "TAKE MY HAND."

The human hesitated for a moment, glancing around them, but then reached up and grabbed the skeleton's gloved hand. Instantly, Papyrus pulled them up into his arms and, using the bones again, quickly stepped back to his place in front of the machine.

Gingerly, Papyrus set the sopping wet child on the ground. Shaking, they sunk down onto their knees in the snow. The skeleton looked back at the platform to see the red tiles surrounding the blue turn to yellow with the final beep. Sharp crackling rang out as sparks shot over the water. He looked away with a wince and a sigh. That would not have been pretty. Papyrus crouched down to the human and reached out to touch their shoulder. They flinched and looked up at him.

"I am sorry about all that human," he said, gazing at the ground guiltily. "I do not wish to hurt someone like you, who obviously cares so much for great puzzles, in such a way…"

Despite everything, the child managed a reassuring smile up at him, and he couldn't help but return it.

"WELL HUMAN!" he proclaimed, straightening up again. "I WILL NOT ALLOW THIS MISADVENTURE TO RUIN OUR PROGRESS!"

The skeleton smiled down at the child, reaching out a gloved hand. "But," he said. "Perhaps we could take a little break before we continue?"

The human pulled themselves back up to their feet and, still smiling, clutched his offered hand. Papyrus gently pulled them forward, leading them along the path. "NOT FOR MY SAKE OF COURSE," He continued grandly. "THE GREAT PAPYRUS HAS SUCH SUPERIOR ENDURANCE, HE NEVER NEEDS TO TAKE BREAKS! BUT YOUR CLOTHES ARE ALL WET, AND I DOUBT IT IS VERY COMFORTABLE. IF I AM TO CAPTURE YOU, THEN YOU OUGHT TO BE COMFORTABLE AND READY FOR IT! I WOULD NOT STOOP SO LOW AS TO FORCE YOU TO ATTEMPT TO BEAT THE GREAT PAPYRUS UNPREPARED! I AM A SKELETON WITH STANDARDS!"

The child followed along, listening to every word and shivering all the while. They soon entered Snowdin Town, and as they passed the first building, Papyrus picked up his pace, moving briskly until his home was in sight. The human trotted along to keep up with him until he stopped.

"This is my home," he said, looking down at them with a welcoming grin. "You can come in and dry off alright?"

The child nodded, and was once again gently pulled forward through the door.