Author's Note:-
This is just a headcanon one-shot that I've been meaning to do for a while, ever since I drew a fanart to go with it. It's one of two theories I have about Gaster's demise, the other one is wildly different but probably not that much nicer n_n' I still don't know what to believe about what happened to him, but this seemed like as good an explanation as any.
I hope you like reading this, and please leave your feedback if you do. Thank you :)

Gasp! It was the middle of the night, and the child Sans was suddenly awoken by a horrible feeling. Oh, God… He felt so sick. Ugh…
"dad…?" Sans mumbled weakly, and achingly turned over in bed as the most vile feeling overcame him. It was like he'd swallowed a knife, and it was cutting him from the inside. He was bleeding… wasn't he? It felt like the very fibres of his being were breaking apart. "arg…" He gagged, and retched. Instinctively Sans put his head over the side of the mattress, pointing his face at the floor. He was going to puke. Ugh. He knew he wouldn't make it to the bathroom in time. He'd have to do it here. He felt a rush of vomit sweeping up from the bottom of his soul, and then… oh. Nothing. Nothing came… the feeling was going. Okay… Okay… "ff." Sans hissed through his agony. Was it over? No… wait. He felt dizzy. Really… really light-headed… He felt hot. Then cold. Then sweaty… His vision went black for a brief moment. He closed his eyes to try and reset it, and he felt a heaviness pulling him in. it wasn't sleep. It was unconsciousness. He had to… he had to open… Open his… Sans opened his eyes, to see that he was still staring at his bedroom floor. It was barely visible in the darkness of the night. Or… was it Sans…? Was it even night-time? He was so confused. So sick… He felt like he was dying. "d…" Sans attempted to call for his father again, when a sudden horrific feeling stopped him. He felt… sharp. Like someone had taken that knife and stabbed it right through his soul. He felt afraid. Deadly afraid. Terrified – whatever! Oh, no… No, no. "pap!" Sans breathed, his magical heart suddenly pounding against his bones. Something was wrong with Papy. He knew it. Papy was dying! "papyrus!" Sans screamed as he leapt out of bed, so fast he tripped over his own bedding. He desperately scrambled to his feet, and bolted out of his room.

As he ran towards Papyrus's bedroom he became annoyed with himself. What was he doing? He was coming to his senses now; he was starting to feel less sick. Enough to know what was going on. He knew where he was, and what time it was. He was at home, and it was the middle of the night. He should be back in bed. He'd had a bad dream. Obviously. He didn't remember it, but… why else would he be so spooked out? There was nothing wrong with Papyrus. Jeez. That was stupid. What was he doing? Sans stopped outside Papyrus's room, and asked himself what the hell was going on. Why was he going to check on him? This was crazy. Papyrus was fine. Why wouldn't he be? If Sans went in that room, Papyrus would wake up and then he'd never go back to sleep, and Gaster would be mad… That was a bad idea. Sans knew it. He should just go back to bed…

No. Sans froze. He didn't want to. He wanted to go back to his room, and go back to sleep… but something told him not to. He had a horrible sickening feeling, that urged him to check on Papyrus. Go… Go. Why? There was nothing wrong with him. Go… "damn." Sans growled, trying to shake this unnerving feeling away. Why…? It didn't even make sense. Go. Go. … … Okay. Fine. Sans didn't get it. For some reason, he really wanted to check on Papyrus, and that feeling kept getting stronger. He couldn't make it go away. … If he was really quiet, maybe Papyrus wouldn't wake up. Okay… Okay. Just five seconds. Just one quick look, really quiet. Sans placed his handle on the door handle, and opened the door as silently as he could.

He stepped into Papyrus's room, stealthily making his way over to the crib… Oh, crap. If Papyrus woke up, Sans was dead. It always took at least an hour to get Papyrus to go to sleep anyway, and he always woke up at the slightest noise… Why was Sans doing this? Gaster would go crazy if Pap woke up. Okay… Okay. Just be real quiet, real quiet…

Sans stood over Papyrus's crib, and stared down at his little brother. It was a wonder his footsteps hadn't been enough to wake Papyrus – as quiet as Sans tried to be, Pap always seemed to be able to hear him. But… he was sleeping. Fast asleep, like he hadn't slept in weeks. Heh. Sans smiled slightly. Okay… He was fine. He was sleeping a little deeper than usual, but that wasn't a bad thing. Seriously, the whole house could do with Papyrus having a good long sleep. Sans waited a moment, just to listen to Papyrus's breathing. … … Okay, it was quieter than normal, but that was okay. It just meant Sans would have to listen really hard. … … … "fuck!" Sans screamed. He wasn't breathing. Papyrus wasn't breathing! "no – no no – pap!" Sans yanked the toddler out of his crib and shook him, smacking his back to try to get a response. "papyrus!" All of a sudden an almighty flood of panic rose up within him, shooting through Sans's soul like gunfire, loud and fast. He breathed frantically, desperately trying to think of what to do. He blew into Papyrus's face, hoping it would shock the toddler into back breathing. Nothing. He pinched him hard, nothing. "pap!" Sans shouted as loud as he could, hoping to scare Papyrus awake. Nothing. Nothing. "no no…" Sans panted. "dad!" He screamed. He felt sick. He felt cold – his entire body was shaking. Why? Why was this happening? He had to think – did Papyrus eat something? Fuck he was always putting stuff in his mouth, and he was always going into Gaster's lab – had he swallowed something?

Desperate, and unable to think of anything else to do, Sans tried to make Papyrus vomit. He stuck his fingers into Papyrus's mouth and tickled the back of his skull, using his magic to try and make Papyrus respond. Splat. Papyrus's entire body flinched, and coughed up… what the hell was that? It was some kind of foul-smelling thick liquid; Sans couldn't make out its colour in the dark. Okay… whatever – it was working! Again! "come on, come on!" Sans pleaded desperately, and once again made the unconscious Papyrus throw up onto him. "pap!" Papyrus wasn't bringing anything else back up, so Sans frantically used his healing magic to the best of his ability, enraged at himself that he wasn't better at it. Why wasn't he better? Why didn't he practice more? Why why why why why!

Hiss. All of a sudden, Sans became flooded with relief. That was Papyrus… He'd taken a breath. "pap?" And another one… another… He was breathing. "oh, thank god." Sans sobbed, collapsing to the floor with the toddler Papyrus held tightly in his arms. He was covered in Papyrus's vomit, and whatever the hell it was Papyrus had ingested. He didn't care. He didn't seem to notice. He was too busy calming down. "okay…" Sans breathed, closing his eyes. "ssh… it's okay, bro. you're okay… can you hear me?" He titled the toddler back to look at his face. "papy?" He was breathing… but his eyes were still closed. "pap?" Sans begged desperately. "pap – wake up!" No… No. Why was this happening? Why wasn't he waking up? "dad…?" Sans cried weakly. "dad!" He had to find him. Gaster would know what to do – he'd be able to revive him. Sans leapt to his feet, and bolted out of the bedroom door.

He knew where Gaster would be. If he wasn't at home, he'd be in his lab. Sans raced there as fast as he could, hating himself that even at this speed he still couldn't move faster. "come on, pap." He breathed frantically, jerkily rubbing Papyrus's back in the hope that he'd get a response. "stay with me. stay with me. almost there. dad'll fix you, just please…" He sobbed. "don't die. don't die don't die don't die…" He chanted the words over and over, as if Papyrus would leave him if he stopped. "please don't. please please please…"

He burst through the door of Gaster's lab, briefly relieved to see Gaster sitting there. In his panicked state Sans didn't even take the time to notice how off Gaster looked. He was sitting on the floor with his face in his palms, tears on his face. Gaster raised his head at the sound of the door opening, and looked at Sans with wet eyes… Then he smiled.
"Sans…" He spoke, and lowered his gaze to Papyrus. "You found him."
"yeah, he – dad, he wasn't breathing!" Sans sobbed, running over to Gaster. "i don't know, i went to check on him – i think he swallowed something in – i mean why the hell do you leave stuff lying around!" Sans screamed, his face filled with fury as he started hurling accusations at his father. "why don't you lock the door or – dad help him!" He cried. "please… he won't wake up."
"What…?" Gaster uttered.

He looked at Papyrus more closely, and his pupils widened. "Sans…" He whispered hoarsely. "What have you done…?"
"me?" Sans wailed. "i didn't do anything – would you just fucking help him! why aren't you helping him you bastard!"
"He's breathing…" Gaster said, almost mournfully. "Oh, Sans… did you get him breathing?"
"yeah but – but he won't wake up." Sans whimpered. "i don't know how to fix him."
"With any luck, we aren't too late." Gaster stated, and rose to his feet. "It can still be peaceful." He made his way over to his desk, and wiped the tears from his face. "He doesn't have to feel any pain."
"what…?" Sans mumbled. "dad, what are you…?" Then he stopped. This… This didn't feel right. Why was Gaster crying? He didn't seem in a rush to help Papyrus at all, and he didn't seem surprised…
"Now." Gaster spoke, returning with a vial of liquid. A thick, foul-smelling liquid… "At this point I'd like to inject it straight into his bones, but if he's breathing there's a chance he'll feel it and wake up. I don't want him to be in any pain."
"what the hell are you doing!" Sans screamed, pulling away from Gaster. "you psycho! why aren't you helping him?" He clutched Papyrus tightly in his arms, his heart racing as all this horror started to make sense. Cold, sick sense. It was impossible to think of anything else – it was the only way to explain… No. No, this couldn't be happening. This was a dream. This was all a horrible, sick dream. Gaster wasn't doing this. Gaster hadn't done this. No. No… No…
"Sans." Gaster groaned. "Please don't make this harder. I can't begin to tell you how painful this is for me…" He ran his hand over his skull, his face twisting in grief. "I loved you boys, and I shouldn't have. You weren't supposed to exist. I must fix it –"
"stay away from me!" Sans roared, using his magic to push Gaster back.

Almost tripping over his own feet he backed away hurriedly, still holding the unconscious Papyrus tightly in his arms. "you tried to kill him!" Sans yelled at the top of his voice, his skull hurting with the sheer volume of his outburst. "murderer!"
"Sans, please!" Gaster protested, and steadily made his way over to the frantic boy. He sniffed back his own tears, and offered Sans a warm smile. "It's okay, Son. It won't hurt him. He's dreaming, he won't feel a thing. It'll all be over in a few minutes, and once he's done we can do you –"
"no!" Sans screamed.

He ran for the door, only to have it slammed shut in his face and locked by Gaster's magic.
"Sans, please." Gaster woefully begged. "Why are you doing this? Papyrus won't wake up. Do you really want to keep him in a coma forever?"
"why are you doing this?" Sans wailed, his eye sockets flooded with tears. No… This wasn't happening. This was too horrible. Papyrus would wake up. He had to wake up.
"It's done." Gaster shrugged sorrowfully, his pupils dimmed in dismay. "I'm sure there's very little left of Papyrus now. He must have gone a few minutes without breathing before you found him – I didn't leave his room myself until I was sure it was too late."
"no, no…" Sans sobbed. His knees felt weak. He lowered himself to the floor, before he could collapse onto it. The grief was overwhelming. His shirt was soaked with tears that couldn't come quick enough. His chest stung viciously, painful and heavy with the sickening weight of this horrific reality. This was too much. Sans ran his hands over his skull in agony, his eyelids scrunched tight, trying his best to wake himself from this devastating nightmare. This wasn't happening… This wasn't happening.
"I… I should have stayed, until the end, just to make sure." Gaster whimpered. "But I couldn't do it. I just… I love him, Sans. I couldn't watch him die."
"please…" Sans prayed softly, wishing harder than he'd ever wished before that this would all go away. That he would just wake up, and this never happened. Please… please…
"But if I'd known you were going to find him, and try to revive him…" Gaster sighed regretfully, and closed his eyes. "You've really ruined this, Sans. It was all going to be so quick and peaceful…" He opened his eyes, and looked down at Sans with such sorrow. Such dismay. "I'm not sure if I can forgive you."
"what?"

Sans stared back at Gaster, and all of a sudden, in that split second it took him to process Gaster's words, his grief was replaced with rage. Hot, fiery, burning rage. It made Sans feel sick. It made him hot. It made his head hurt; it made him feel dizzy… His pupils disappeared from his eyes. He couldn't see. He couldn't focus. Not on anything, except one thought. One remedy, that would put out the fire of his anger. "you…" Sans hissed. "you… don't think you can forgive me…?" He set Papyrus down, and climbed to his feet. He looked at Gaster, his eyes glowing in a way they never had before… in a way that was terrifying. Then, he screamed. "you murdered my brother!"
"Argh!" Gaster grunted, winded as the force of Sans's rage struck him and set him flying back towards his own creations. His spine cracked as he landed harshly against the large metal lining of his latest invention, something even Sans didn't know about. Sans barely noticed the machine. He paid no attention to his surroundings; he had no idea what he was pushing Gaster against with his magic; he had no idea how many dangerous chemicals and inventions there were in here, all things that Gaster could easily use to end his life. He didn't care. Papyrus was dying, and it was Gaster's fault. Other than that… Sans didn't care. "S-Sans…"

Gaster's chest heaved as he breathed frantically, his pupils wide with shock as he watched the enraged youth approach him. One of San's pupils was glowing. Bright blue, so powerful and so charged with emotion that a mist of blue magic has begun to seep from it, his body unable to contain the turmoil in his soul. He was angry. Crazed. He had to be stopped. "Sans, listen to me!" Gaster ordered, using his own magic to push Sans back. Sans let out a cry as Gaster used his magic to lift him up into the air and he squeezed him. He tightened the squeeze on Sans's bones, trying his best not to become weakened by the screams of pain that emitted from San's hurting body. "You only have yourself to blame for this!" Gaster barked. He closed his eyes tight, ignoring Sans's cries. He couldn't stand this… This wasn't what he wanted. "I wanted it to be peaceful." Gaster moaned. "I didn't want you to feel any pain – I don't want to have to do this to you."
"fuck… fuck you!" Sans snarled. He burst out of Gaster's magical hold, much to Gaster's surprise and horror. Where was Sans getting all of this strength? What had spurred him to fight so hard? Could it be… Papyrus? They had such a strong bond. That was why Gaster had wanted to end Papyrus first. He thought that with Papyrus gone, Sans wouldn't fight as hard, or perhaps not even at all. It would be pleasant, and peaceful… Not like this. This was horrific. Sans was putting up a greater fight than Gaster had ever imagined – he would have to end Sans with brute force. Oh, this wasn't how he wanted it to go… This was the last thing he wanted in the world.
"Sans, please!" Gaster begged, using his magic to once again restrain Sans. "It doesn't have to be this way. Just drink the serum, and you can be with Papyrus –"
"fuck you!"

Sans threw a wave of magic directly at Gaster. He didn't mean it to be as powerful as it was; he didn't mean anything. He was flooded with adrenaline, overcome by emotions and unable to control even the smallest of his own movements. He didn't mean to hit Gaster that hard… but he did. Gaster threw his hands up to defend himself, one behind the other, in a pitiful effort to try and disperse the beam of magic that Sans had sent flying his way. His efforts were futile. Gaster's hands were no match for this powerful beam; it burst straight through his open palms as if they were mere air, leaving behind them two great circular holes in his hands. Gaster screamed in agony, his palms flooded with pain as the magic burned his bones to dust, but the pain of having his hands almost destroyed was nothing compared to the overwhelming impact of Sans's magic hitting his skull.

Crack. It cascaded across him; it hit Gaster right in the middle of his face, with such force it almost knocked him out. He was lucky, though. He was lucky his hands had absorbed most of the attack, otherwise he would certainly be dead. It struck him in the centre of his face, but it didn't have enough power left to burst through his skull. All it could manage was to leave him fractured. Gaster was almost blinded as the beam of magic burst across his eyes, with such an impact it split his skull in two places. He could taste his own bone marrow. He could feel it dripping from his eye, past his teeth… He knew he had a split there, from his right eye to his mouth. He could feel it. Another one, as well. On the top of his skull. The pain… It was so intense he almost blacked out. His vision disappeared for a moment, and threatened to take Gaster with it, until Gaster managed to fight his way back into consciousness. If this top fracture was only an inch or so deeper, he would be dead. "d… dad?"

The attack seemed to calm him. Sans. Briefly, Sans seemed to come to his senses. He stared at Gaster with wide, bright pupils, trembling in shock. "oh… oh my god." He choked. He breathed frantically as he stared at what he had done. He'd burned holes in Gaster's palms; he'd split his skull in two places… God, he could have killed him! How was Gaster not dead? "d-dad!" Sans stammered.
"It… It's quite alright…" Gaster mumbled, clutching his own skull in what was left of his hands. "I'll… I'll be alright." He stumbled slightly, concussed. He leaned back against the metal machine, and allowed himself a short moment to focus, to regain his balance and his composure.
"this is a dream." Sans whimpered. He was scared. This wasn't happening. It couldn't be. None of this was real. This was too sick. It had to be a dream… "dad, i want to wake up."
"Hm." Gaster chuckled, causing Sans to become confused. Why was he laughing…? "Oh… Sans, you aren't even asleep yet." Gaster said. He looked up at Sans, and smiled. "Son. Please, let's end this." He smoothed. "I don't want you to endure any more pain."
"what…?" Sans choked. No… No. It wasn't still carrying on? It couldn't be!
"You can go to sleep." Gaster said. "And it will all be over."
"no…" Sans shook his head violently. No… please.
"Just drink the serum." Gaster smiled at Sans, bone marrow leaking from his fractures. It poured from his right eye, down his cheek and onto his clothes; and it poured from the top of his skull, down his half-closed left eye, an eye in which he was now partially blind, down his face, and onto his mouth… "And you can be with Papy."
"no!"

Gaster gasped breathlessly as Sans's rage fled to the surface once more, and Gaster found himself lifted up into the air. "you're evil!" Sans screamed, his blue pupil returning as he glared up at Gaster. "you killed papyrus!"
"Yes!" Gaster snapped back. "And that isn't going to change! Please, let me just finish it! Let me make it right!"
"why!" Sans yelled.
"You were never supposed to exist!" Gaster protested. "Let me erase you! You have to!"
"you psycho…" Sans hissed. He closed his eyes, desperately trying to contain his own rage. He couldn't. He had to kill him. Gaster had taken everything away from Sans – he'd murdered a baby! He didn't deserve to live. He didn't deserve…
"S-Sans." The fear in Gaster's voice caught Sans's attention. He opened his eyes to see that Gaster was staring below him, looking worried all of a sudden. "Stop." Gaster begged. "You don't know what you're doing."
"huh…?" Sans followed Gaster's gaze, and realised he was holding Gaster directly above that machine. What did that thing do anyway? It was always whirring and making noises… What was it for?
"Sans!" Gaster barked. "Sans, put me down! You don't want it to end like this!"
"… hm." Sans grunted, and he spitefully let Gaster go.

He wouldn't have done. If Gaster hadn't begged him. If he hadn't been so afraid to be dropped into the machine, Sans wouldn't have done it. He wanted to hurt Gaster, and that seemed like the easiest way. He didn't expect him to die. He didn't know what to expect – he hadn't even thought about it. It was just a reaction, in the heat of the moment… He didn't even fully realise there could be any real danger to it until he heard Gaster screaming, and by then it was too late. All at once, Sans came to his senses. The hot wave of fury that had engulfed his soul subsided, and in its place lay a cold, harsh fear. Shit! "dad!" Sans screamed. He threw his hands onto the machine and scrambled up to the top, losing his footing in his hurry. He almost fell but he caught himself, and he made his way up to the top, and looked down… onto glass. What the hell was this? The machine… it had thrown a thick glass barrier across its opening, locking Gaster inside. Like it was devouring him.
"Sans!" Gaster snarled, reaching up to the glass from what looked like… nothingness. It was like a whirlwind, but… God, what the hell was this machine? Gaster was… changing. His body was stretching, as if he were being pulled by some unseen force. "Help me!" Gaster cried, his voice barely even audible behind the thick layer of glass. "Son, please!"
"h-how…?" Sans breathed, his pupils wide. He banged on the glass in a feeble attempt to break it, but he couldn't. Even if he had all the strength in the world, there was no way he could save Gaster now. "i can't – dad, what is this?" What was this machine even for…? Was it some kind of weapon? Why had Gaster built it? "what were you going to do with this!" Sans demanded, his anger getting the better of him once again. He didn't know how to feel. His brother was dead. Because of this man, his own father. He shouldn't help him… He didn't want to help him.
"Help me!" Gaster screamed, his voice becoming more distant as the dark vortex of the machine pulled him in. More distant… and more desperate. "Sans, what are you doing!" His face was changing… He looked angry. "You're killing me!" He roared. "Sans! This is your doing! You killed me!"
"shut up!" Sans screamed, slamming his palms into the glass. "go to hell!" He let out a gasp, his pupils widening as Gaster started to… disperse. Oh, God… what was happening to him? His body was becoming stretched, into pieces – it was like he was teleporting or something, but… not his whole body, not at the same time. "oh my god." Sans gagged. He felt sick. What the hell was he witnessing? "dad…" Sans choked weakly. "dad –"

Whirr. Sans let out a cry as the machine's motor started spinning wildly, almost deafening him with its sound. The entire unit started to shake, as if it were about to explode. What was happening! "dad!" Sans screamed, his pupils brightening in fright. What was going on? What was this thing? What was it doing? "dad!"

Then nothing. All of a sudden, the motor stopped. The machine stopped moving, and all the lights in the lab went out. Every electrical device that was on suddenly switched off. Maybe the machine had blown a fuse. It seemed broken, anyway. Broken… with Gaster still on the inside? "dad…?" Sans uttered weakly. He pressed his skull against the glass, trying to make out… anything at all. There was nothing. Nothing that he could see, anyway. Gaster wasn't there. Sans was sure of it. Somehow, he was sure. Gaster was gone. This… this thing… it had taken him. He knew it. He didn't even know what the hell this was, but… he knew that Gaster was gone. … It was Sans's fault. He'd dropped him into this machine. He'd made it take Gaster. … Truth be told, he didn't even feel bad. He didn't… feel anything. But he didn't need to. This wasn't real, right? It wasn't really happening? No. it wasn't real. It wasn't real. It was all just a dream. "wake up." Sans whispered to himself, his skull grinding against the glass as if he were trying to bury his way into reality. "wake up." He whispered more harshly, more fiercely. "wake up." His nails scratched against the glass, so much so that it hurt. He banged his knees into the harsh metal of the machine, he would break his kneecaps if he had to. If that was what it took for him to wake up. To get the hell out of here, and back in his bed with dad and Papy, everybody safe and unharmed. Please… please. "wake up." Sans sobbed. "wake up! wake up! what's wrong with you? stop being so lazy, wake up!" He let out a loud moan, rolling onto his back in agony as he begged with all his might to be taken away from here. Away – anywhere. Anywhere away from here! "wake up!" He pounded his palms against the glass, his feet kicking against the metal of the machine. "wake up! wake up!"
xxx
"wake up… wake up." In the middle of the night, in the cold darkness of Gaster's lab, a weak voice trembled through the blackness. Tears trickling down his face, gliding over the stains where their predecessors had dried, Sans sobbed through his exhaustion. His eyes were hollow. He was dehydrated. He was tired. Tired beyond belief. He just… he just wanted… "papy, please…" Sans whispered. "please wake up."

Now on the cold floor of the lab, Sans help the unconscious Papyrus in his arms. He rocked back and forth, rubbing the toddler's back and pinching him as harshly as he could. He begged. He pleaded. He did whatever he could think of to bring Papyrus back to life. He was exhausted. How long had they been here now…? An hour? Two? He didn't know. He wanted to sleep. He was so drained… He'd spent the last… however long… putting all his energy into Papyrus. He gave Papyrus all the magic he had; he concentrated so hard… He didn't even know he could concentrate that hard. "please." Sans whispered, as loud as he could through his fatigue. "please, pap…" He closed his eyes. He couldn't keep them open anymore. He couldn't focus… He'd put so much energy into trying to revive Papyrus. He'd never be able to concentrate on anything ever again. He felt sluggish, like he'd lost a part of his soul. It hadn't been in vain, had it…? Even if he had to sleep forever – even if he felt tired and groggy for the rest of his life, even if he never amounted to anything, and even if he never, ever reached the Surface… if it could just make Papyrus wake up… "wake up." Sans begged. "papy, please… i… i can't – i don't have anything left, bro." He tried to pour some more magic into Papyrus. He tried to give Papyrus more of his life force… but he couldn't. He'd drained himself entirely; if he gave any more he would die. He felt like a zombie. He couldn't think straight. He couldn't focus. He couldn't move. He was just tired… So tired. "pap…" Sans whispered. "pap, please…" He started to sob, hanging his head in dismay. "please…"
"S-SANS…?"

Sans couldn't even gasp. It was hard enough just opening his eyes… but he did. He opened them, and he felt joy like he never could imagine when he saw Papyrus staring back at him. Papyrus was awake. Papyrus was awake!
"oh my god." Sans sobbed, pulling Papyrus into a tight hug. "oh god, thank you. thank you thank you…" He whispered desperately, as if Papyrus would go away again if he didn't emphasise how truly thankful he was for this moment. Papy was back… Papy was back! "papy." Sans moaned into Papyrus's skull, tears streaming down his face. "bro! you're okay!"
"HURTS." Papyrus sulked.
"it… it hurts?" Sans pulled away, just far enough to look at him. "from the poison?"

Papyrus just stared at him blankly. He didn't know what poison was, of course he didn't! What was Sans thinking?
"DADDY." Papyrus uttered, unable to think of anything else to say. "DADDY?"
"oh…" Sans choked. Jeez. What the hell was he supposed to say? He didn't…. He had no idea what had happened. He didn't know where Gaster was. Was he dead, or…? … He deserved to be. Sans's soul flickered with rage for a brief moment, before the soft whimpering of Papyrus calmed him down. "it's okay, papy." Sans soothed, gently rocking the toddler. "ssh. don't worry. daddy's, uh… … he's on vacation. it's just you and me for now, okay bro?" He smiled, and closed his eyes. "but it's okay. i'm gonna take care of you. you'll be safe…"
"ICKY." Papyrus said, almost sulking.
"icky?" Sans looked down at him, confused. Papyrus was pointing at his mouth. Oh… "daddy gave you some medicine, huh? didn't you like it?"
"NO!" Papyrus huffed, shaking his head. "ICKY."
"heh. well… it's okay. you don't have to drink that ever again." Sans replied, returning to his soothing rocking. It was okay now. He told himself repeatedly, forcing himself to believe it. Things were different now. Horrible stuff had happened… but it was all okay. Papyrus was back. He was safe. That was all that mattered. "you don't have to drink anything you don't want to." Sans smiled. "actually, you can eat and drink whatever you want for the rest of your life."
"SPETTI!" Papyrus grinned, his pupils lighting up.
"heh you want some spaghetti, bro?" Sans looked down at Papyrus, and watched as the toddler nodded excitedly.
"SPETTI! SPETTI!"
"okay." Sans sniggered, a warm wave of relief blanketing his soul. Papyrus was back to normal. He was okay. A little confused maybe, but okay. Thank God. Thank God! "come on then, kiddo." Sans struggled to his feet and leaned against the wall, almost losing his balance in his weakened state. "but… you're gonna have to share." He had to eat something. He was about to pass out. He wanted to sleep, so badly… But he was terrified to right now. He wanted to keep an eye on Papyrus. He had to make sure this was real. This part was real. The whole thing had been real… and now Papyrus was alright. Jeez. When he finally felt safe enough to sleep, Sans knew it would be for a long time. He craved it. He'd lost so much energy… but it was worth it. For Papy. He wasn't going to complain.

Sans made his way towards the laboratory door, with the conscious Papyrus in his arms. He opened the door, and he left the lab… and he locked the door behind them. He didn't look back once. He left the machine in darkness.