Gaster Blaster Transformation Oneshots (ON HIATUS)

A Brother's Hidden Love

Yeah. No picture. I need to follow through on my promises to draw the pictures for these. :/
Anyway, this one is SwapFell and was requested by UndertaleWeirdo89
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   Papyrus rubbed his eye sockets as he slowly got out of bed. He walked over to the stairs, barely noticing his brother standing in the doorway of his own room.
"Hmph. I was wondering when your lazy ass was gonna get outta bed. No wonder you never show up to sentry duty anymore," Sans growled.
"What are ya goin' on about now?!" Papyrus snapped.
"Just look at yourself! You look even shittier with each passing day!" Sans hissed, gesturing to Papyrus angrily.
Papyrus looked down at himself. Sans was right; he really did look like shit.
"And since when do you walk on your tip-toes like that?!" Sans snorted, pointing to Papyrus's legs.
"What do you mean?! I've never..." Papyrus trailed off as he looked closer at his feet.
Sans was right. Something about the way he was standing seemed... off.
"That's what I thought. Y'know, I could point out plenty of other things wrong with you, but I'm not even gonna bother. Why should I when you clearly can't take the time to look in the mirror?" Sans huffed angrily.
"Wha-"
"Shut it. I'm done talking to you," Sans interrupted, slamming the door shut on Papyrus's face.
   Papyrus stood there for a moment with a puzzled expression on his face. "What does he mean? What else is wrong with me?"
   He stumbled to the bathroom, turning on the lights so that he could actually see himself in the mirror. He hesitantly took off his hood, revealing several small ridges along the back of his skull.
  "What the- When did this happen?!" Papyrus exclaimed, running his hand along the back of his skull.
   He turned his head to the side, and noticed out of the corner of his eye that his face was slightly elongated. His teeth almost seemed somewhat sharper than usual.
   He looked down at his hands, noticing for the first time that his fingertips were seemingly sharper; almost resembling claws of some sort. His gaze slowly went down to his feet, which he realized had grown longer and the tips of his toes had grown sharper.
   That was when he felt something coil around his leg. He looked at his leg, noticing the tail for the first time. The tip of his tail twitched slightly as he stared down at it.
   "I don't remember this... What's going on with me? What happened? Why can't I remember anything?" Papyrus mumbled, holding a hand to his forehead.
   He finally stumbled out of the bathroom, clumsily making his way down the stairs. He heard a sigh from the corner of the room, causing him to flinch.
   "Put your hood back on, you dumbass. I don't wanna see your hideous face. And do something with that tail of yours. It makes you look even dumber than you usually do," Sans growled, walking towards the front door and going outside.
   Papyrus quickly pulled his hood back over his head, hiding the small ridges along the back of his skull. He focused on his tail, wondering how he was going to hide it. The damn thing seemed to have a mind of its own, so hiding it was going to be difficult.
   He grabbed his tail, trying to force it into his pant leg. It was better than nothing. It was less obvious, at least. Papyrus sighed as he shuffled to the door, stepping outside and heading to his sentry post.
   Once he got there, he sat down and stared up at the treetops. A distant look clouded his already-dull eye sockets as he lost himself in his own thoughts.
After several minutes of staring off into the distance, Papyrus became aware of a strange burning pain in his chest. It had started off as a dull ache, but was gradually escalating into a searing pain, almost as if his chest was on fire and was burning him from the inside.
Something in his mind screamed at him to get away. Without thinking, Papyrus stumbled to his feet and tried to run deeper into the woods. His limbs felt uncoordinated and heavy all of a sudden, slowing his pace as he made a mad-dash to the forest.
He nearly lost his balance, lurching forward and grabbing onto a nearby tree, digging his sharpened fingertips into the bark to prevent himself from falling. He felt dizzy and somewhat feverish, despite the weather conditions around him.
Eventually, Papyrus collapsed in the snow due to the building ache in his bones. He rolled onto his side, curling up into a ball as he tried to block out the pain.
His breathing was gradually becoming faster and shakier as he struggled to keep himself from crying out in agony as the burning pain spread through his entire body. Sweat poured from his skull as he desperately tried to hold himself together.
He gritted his teeth as a sharp pain jolted through his spine. He felt his tail curl up closer to his body as he gripped his own shoulders with his shaking hands. He winced as he felt his claws dig into his arms, but he barely noticed it over the sharp pain that overtook him once more.
He squeezed his eyes shut, wishing that the pain would stop. He rolled onto his back, barely holding back a scream of agony as the movement sent a sharp pain through his body. Papyrus grunted as pain shot through his spine once more. He felt like he was being ripped apart from the inside.
That was when he heard the sound of bones cracking. He let out a groan as pain jolted through him, the pain somewhat worse this time. He arched his spine as he felt it begin to snap and twist and re-set itself with a series of dry snaps.
Papyrus barely had time to roll back over onto his side before massive spikes burst through the fabric of his jacket. He panted heavily as the pain subsided for a few seconds. But the moment was short-lived, for after those few blissful seconds, pain seared through him once more, causing Papyrus to scream in agony.
   He was so lost in his own pain that he didn't notice that his brother had followed him into the forest.
   "...Pap? What's wrong?"
   Papyrus looked up. Sans was staring down at him with a mixture of confusion and annoyance in his eyes. Papyrus was about to respond, but a sharp pain in his legs stopped him. Another groan forced itself out from between his clenched teeth, this one slightly louder than the first.
   Papyrus could feel his legs begin to extend into digitigrade, sending another wave of unbearable pain through him.
   Sans stepped back as the transformation really began to hit Papyrus. He watched as his brother's bones snapped and reformed, growing longer and seemingly thicker than before. Papyrus's screams were becoming increasingly animalistic as the minutes dragged by.
   Normally, Sans would have enjoyed this moment. He loved seeing others suffer. It was a weird obsession, but it wasn't uncommon in the universe that he lived in.
   But witnessing something like this somehow scared Sans. And watching it happen to his own brother didn't seem to make it any better.
   Sans lost himself in his own thoughts, completely unaware of what his brother had become until he looked up.
   Looming over him was a massive skeletal beast with a feral gleam in his blazing red eyes. Sans jumped back, somewhat startled by the huge creature.
   The beast growled as he crept closer to Sans. Red smoke poured from his jaws as he stared down at the small skeleton below him.
   "Papyrus! Snap out of it!" Sans shouted.
   The beast roared as he reared up onto his back legs, proceeding to slam his clawed hands back down on the snowy ground, right where Sans had been standing only moments before.
   "So, we're gonna play like that, huh?"
   The beast snarled as he turned to face the smaller skeleton.
   "Whatever you want, bro," Sans chuckled, activating his magic and holding the beast down.
   The huge creature roared as he struggled to escape Sans's magic.
   "Look, I'm sorry I have to do this to you," Sans murmured, his own words surprising him.
   Clearly, it surprised the beast as well, because his thrashing began to weaken.
   "I'm sorry you've had to go through this. I wish I could tell you that I understand what you're going through, but unfortunately I haven't had any experience with something like this," Sans mumbled.
   The beast growled softly, the fierce red light in his eyes dulling slightly.
   "I don't think I tell you this enough, but I... I love you," Sans whispered, looking away from the beast.
   The huge creature looked at Sans in confusion.
   "I know that it's hard to believe sometimes, but I do care about you. I take you for granted so much that I forget that you are a real, living being. And I'm sorry for all that I've put you through over the years," Sans said in a hushed voice.
   The smaller skeleton walked over to the huge beast lying in the center of the clearing, who was still held in place by Sans's magic. Sans reached out and rested a gloved hand on the beast's muzzle.
   "Do you... forgive me?"
   The beast closed his eyes for a brief moment. When he opened them again, his eyes were rid of their feral gleam.
   "Yesss," the beast rumbled.
   A smile crossed Sans's face, but this one was genuinely happy for once. He chuckled as he hugged Papyrus's muzzle.
   "Thank you bro."

A/N: Awww! It got really fluffy at the end!
   Wow, this one was actually really fun to write. :3
   Anyways, leave your requests in the comments below! I'll do any au.
   Hope you guys have been enjoying this as much as I have! :3
-Sora