Gaster Blaster Transformation Oneshots (ON HIATUS)

Last Resort🌙

   Ok, this was actually inspired by something I saw on Grandma_DNA 's message board awhile back, and I thought it sounded like a fun idea to write a oneshot on.
   Also, blueberry_sans8 and dreamtalefangirl , I know you guys requested Nightmare awhile ago as well, so this one's kinda for you.
   So an actual request for once! YAY! XD
(Holy crap though, that was a lot of tags. 0-0)
   Artwork above was drawn by me! :D

   Anyway, enjoy the suffering of the edgy goop-skele! >:3
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Nightmare's gaze scanned over the distressed, angered mob of people that were rapidly closing in on him, desperately trying to find a way out of this situation.
He hadn't meant for it to become like this! But now... It was too late to undo what had been done.
Everything that he and his brother had sought to protect was gone; rotted away, like all of the cheer that had once been plentiful in the land.
The skeleton held his own dark fruit closer to his chest, still backing away from the crowd and drawing closer and closer to the Tree.
He could feel whatever passed for his soul beginning to beat faster, a strong sense of panic coursing through him as the cluster of enraged people continued to close in on him.
"B-Back off! It's not like I could help any of this! Go complain to my brother about it if you don't like it!" Nightmare shouted, his eyelights flaring brighter for a moment.
Yet, despite his attempts to command the crowd, they wouldn't listen. They were too blinded by rage. They would stop at nothing until he had payed for what he'd done.
He frantically looked around, trying to find an escape one last time.

...He couldn't find one.
He turned his gaze to look down at the apples in his arms, an idea coming to mind. He didn't have much time to really think it through before he acted.
He kept a firm grasp on a single fruit, letting the others fall to the ground as he raised it to his mouth.
...Hopefully he wouldn't regret this...
He bit into the apple, grimacing at its strange, bitter taste. But he didn't stop at just one bite. No. He kept going, until he had consumed all but the core, which he dropped once he had finished.
At first, nothing happened... But then the sharp pain bloomed within his ribcage, the source being at his 'soul'.
Nightmare doubled over, groaning in anguish as the terrible pain rapidly grew worse, his entire body shuddering in response. He felt weak, his chest tight and his limbs uncoordinated and heavy.
His breath was coming in short ragged gasps as he struggled to stay aware. It was getting harder to think. It hurt too damn much to do anything.
   He began to sob, clutching at the space where his stomach would be (if he had one) as he collapsed to the ground. A strange, black substance began to mix into his tears as it leaked from his eye sockets, starting as a mere trickle before it became like a continuous stream.
   He began to cough and gag as the bitter taste of the corrupted fruit returned, making him feel extremely sick. He was completely unaware of the flecks of black liquid that sprayed from his mouth as he choked on all the toxic negativity he'd been forced to swallow.
...And then, he heard a loud cracking sound. Through the burning pain that had spread across his entire body, he felt a completely different sensation begin. His bones felt like they were shifting and rearranging themselves. It was nauseating.
He suddenly puked up a stream of the thick, black substance, his bones rattling from the uncontrollable spasms that had gripped him in the moment.
   "...Nightmare!"
   He felt his 'soul' lurch at the sound of his brother's voice. His gaze snapped up, his eyelights completely filling up his sockets. The black liquid that was pouring out of his eyes had begun to drip from his mouth now, almost as if he were overflowing with darkness.
   "S-Stay away!" He shouted, just before he fell into another violent fit of coughing and sputtering.
   Dream skidded to a halt a short distance away from the other skeleton, his eyes wide. "Brother... Wh-What's going on?"
   He looked down at the corrupted apples that were scattered around his brother's shuddering form, a chill running down his spine as he spotted a single, rotted core amongst the other fruit. "Wait... D-Did you...?"
   Nightmare groaned in agony, falling forward while clutching frantically at his midsection. "Oh g-god... It hurts... I-It hurts so much..."
   "Just... h-hold on... I-I can help..."
   "N O ."
   Dream twitched at his brother's response. Nightmare fixated the other skeleton with a fierce glare. "I DON'T NEED YOUR HELP."
Dream backed away as he noticed a strange, black goop beginning to drip down from various fractures that had appeared across his skull, concealing his right eye from view. The fear only grew worse as he realized that Nightmare's skull was beginning to change, his face stretching forward into a muzzle while several twisted horns emerged along the back of his head.
   His pained grimace contorted into a sickening, sharp-toothed grin as the dark corruption began to consume him, the black substance oozing from every fissure in his skeletal body.
The smile didn't stay put for long though. It quickly morphed back into an expression of anguish as pain began to ripple down his back, his spine beginning to reset itself with a series of jarring snaps.
   Dream flinched back, the color draining from his eyes. Nightmare inhaled sharply, tightly gripping the sides of his ribcage with both hands, the fabric of his jacket tearing beneath his grasp.
"J-Just go away... I don't need you..." The corrupted skeleton hissed bitterly, his voice strangely double-toned.
"Nightmare, please... I want to help you... But I can't if you keep pushing me away!"
Nightmare grunted in pain, suddenly slamming his fist down on the ground with a surprising amount of force. "I SAID THAT I DON'T NEED YOUR GODDAMN HELP!"
   The moment of rage left him as quickly as it had come, his body relaxing slightly. "Just g-go... You can't help me now..."
   Dream was quiet. Nightmare's breathing became labored once more as the pain rose up again, causing him to cry out. His backbone appeared to stick out along the back of his jacket, forming a distinct ridge as something began to press against the relatively tight-fitting fabric.
   A look of horror crossed Dream's face as several massive spikes suddenly shot up from Nightmare's vertebrae, at the same moment that four black tendrils burst out from the back of his ribcage, shattering the bone. The scream that escaped him was gut-wrenching. His voice was unnaturally deep and raspy, but his regular voice was still audible underneath the low-pitched snarl.
   "B-Brother..."
   Nightmare's head snapped up, his eyes fixated on his brother. Dream shuddered as he realized that his brother's eyelights were slowly changing from their usual purple color, to a chilling icy-blue.
   The black goop was completely covering the right side of his face, and rapidly spreading to the other side as well.
   "I HATE YOU..." He hissed, his voice almost seeming to gurgle ever-so-slightly. "I HATE YOU... SSO MUCHH..."
He curled in on himself with a loud groan, with one arm still tightly hugging his midsection. Dream shuddered as he realized that, on his brother's visible hand, he could see razor sharp claws on the tips of his fingers. That would explain why he had been able to tear his jacket like he did.
   Nightmare fell down onto his side, his body convulsing violently as the changes really began to hit him. His legs jerked as his feet began to splinter and shift, growing longer as the tips of his toes grew sharper, tearing apart his boots in the process.
   A tail grew out from the base of his spine, coiling around his leg idly as he whimpered softly. He desperately clawed at his sides, the burning pain that was radiating deep within his chest becoming too much to handle.
He could feel the remains of his clothes becoming tighter as his bones started to distend and thicken, his ribcage expanding as more spikes formed across his shoulder blades and on his elbows. He cried out, though his voice wasn't even recognizable as his own anymore.
Dream backed away, his eyes wide with horror as he watched the torture. He couldn't do anything else. He didn't know how to help, and any time he tried, he would be pushed away again.
   Nightmare let out a deep roar, which shook the air around him with its volume. His form was growing larger and larger, and the black corruption was spreading further and further, until it had consumed his entire body.
   He slammed his arm down on the ground, just before he shakily managed to rise to his feet. He staggered, his uncovered eye only half-open as he struggled to find his balance.
   His still-labored breathing rumbled strangely in his ribcage, and he growled hoarsely, though it wasn't out of aggression.
   Dream hesitantly took a step towards his disoriented brother, his arms held out at his sides. "N-Nightmare?"
   The beast managed to steady himself, propping his abnormally large body up against the wilted tree with a single tendril. He shook his head before his mind registered that someone was trying to get his attention.
   A gurgling hiss escaped him as his gaze became fixated on his brother, who seemed so small and insignificant now.
   He let out a rumbling laugh, a twisted grin spreading across his face. "Hey Drream... why don't ya give yourr big brro a hug?"
   Dream took a few steps back, his pupils only mere pinpricks. "W-We can fix this! I-I promise..."
   Nightmare snorted in disbelief. "I don't want to be fixed, brrotherr... In fact, I love the new forrm! Y'know why?"
   Dream slowly shook his head, afraid to know the answer.
   "'Cuz I can do this!" He suddenly lunged off to the side, attacking the innocent bystanders before they could react.
   His tendrils sliced through them like a butcher's cleaver, easily tearing them into halves. Dream covered his mouth, barely managing to keep himself from vomiting as blood splattered through the air, the shrieks of the dismembered civilians making him sick.
   Nightmare turned to another part of the crowd, darting forward and grabbing one person in his mouth, while pinning down two others with each clawed hand. He bit down, severing the neck of the person in his maw, while he simply crushed the two that were underfoot.
   The sound of bone crunching was absolutely nauseating to Dream, and he had to turn away as the beast ruthlessly murdered countless humans and monsters, with no restraint.
   Finally, after what felt like forever, he returned. He was covered in both blood and dust, and he had a deranged grin plastered onto his face.
   "Aww... You didn't like my little parrty trrick?"
   Dream fell to his knees, burying his face in his hands. "P-Please... N-No more... They don't..."
   "What? They don't what? Deserrve to die?"
   "No! They didn't do anything wrong! And you slaughtered them!" Dream blurted out, tears streaming down his face.
   "Wrrong. Do you have any idea what they did to me, day in and day out?? What they said to me??" Nightmare hissed, his tail flicking back and forth behind him.
   Dream was silent.
   "See? You don't know everrything that goes on herre. You wouldn't know that everryone hated me, just because I was meant to prrotect everrything negative. All theirr angerr, all theirr sadness, all theirr fearr... I was meant to prrotect that, but all I got was hatrred and discrrimination!"
   Dream flinched, his eye sockets going blank.
   "You wouldn't underrstand. You'rre everryone's herro. You wouldn't know what it's like to be trreated like a crriminal, and forr no good rreason!"
   "I'M SORRY!" Dream cried, cutting his brother off.
   The beast looked down at the tiny skeleton, a scowl on his face. "Oh, now you'rre crrying? You'rre pathetic... Weak..." He turned his back to Dream. "And I don't want to considerr you as my brrotherr anymorre."
   Dream bowed his head, sobbing quietly as the monstrous creature that his brother had become left him, his goop-covered form melting away and disappearing from sight.

   Boom! Another angsty one! :3
   And just a quick note: I am aware that Nightmare canonically ate ALL the apples, not just one. But when I initially looked into his backstory, I saw that the common interpretation was just a single bite. And even after writing that part, I just didn't feel like fixing it. :P
   And I might have gotten a bit carried away with the scene where Nightmare attacks everyone... But god damn, I was smiling like a freaking psycho when I wrote all those gory details. XD
   In all fairness though, the original Dreamtale comic got pretty bloody in that same scene. I just took it up a notch lmao.

   So, what did y'all think of this one? I'm really happy with how it turned out, especially considering that there were two different transformations occurring at the exact same time.
   I know that a lot of you aren't as into the bloody stuff... But dammit, those are the most fun ones to write!

   Anyway. Please do leave votes and comments! They absolutely make my day, and they let me know that I'm doing something right!
   Until the next update, stay determined!
   -Sora