#gasterblastober

The pulse of mysterious energy hit Sans, dazing him long enough for the wild Blaster to tackle into him! As Sans soared through the air and out of their sights, the other two skeletons could only scream.

What was this thing…!? Where had it come from…? And what was it even doing in a forest like this?

Papyrus and Gaster rushed at the uncontrolled Blaster, grabbing on and trying to restrain it, but ended up thrown off! Another burst of magic energy rushed into Papyrus directly as he was launched into a tree!

The skeleton managed to quickly recover, getting to his feet, but within moments… the real pain started. A wet scream tore from his throat as he clutched at his chest! It felt like lava was coursing through his bones as his torso expanded, straining his battle body. His shoulders quivered, before violently snapping forward.

The Blaster took advantage of Papyrus’ newly forward-facing limbs, latching on with its razor-sharp teeth. The skeleton screeched in agony, but that was nothing compared to the changes spreading downwards. Sweat cascaded down his skull, his face going slightly red at the realisation of what was happening. Why THERE!? Why now!?

His shifting pelvis was straining against his briefs, making the whole ordeal uncomfortable in more ways than one. Papyrus wanted to pull them off, but the Blaster on his arms meant all he could do was helplessly watch. His briefs kept getting tighter and tighter, until finally… they had enough of the pressure.

They snapped off, going flying like from out of a slingshot! A long, blade-tipped tail, freed from his briefs and easily twice the length of his torso, lashed out from behind him, smashing into the Blaster! The demonic skull crumbled from the powerful blow, its remains colliding with another tree and tumbling to the bottom, unmoving.

Something on the tree caught Papyrus’ gaze – if he wasn’t so scared about what was happening to him right now, he would have chuckled. His briefs were hanging off the tree, a sight just like out of a slapstick cartoon.

His brief moment of respite was interrupted as burning spread to his arms. His bones thickened and fortified as the awful mutation progressed from his upper arms outwards. Papyrus tried to keep his breathing steady and regain control over his magic, but each time he thought he had regained control, he slipped again – like a mountain climber who thought he nearly reached the top, but when he got there, there was still another stretch of mountain to go.

Once the change reached his hands, his fingers spasmed, causing his gloves to bulge and twist, before shredding! Five sharp pointed claws lay at the ends of his fingers and thumbs, and they were only getting sharper as his hands grew to match his arms.

His metacarpals stretched out, each snap drawing a cry of pain out of the mutating skeleton. Meanwhile, his thumbs slid slightly down his hands, as if they couldn’t decide whether they wanted to stay with the other fingers or not. In fact, his hands as a whole couldn’t seem to decide whether they were human-like hands, or beast-like forepaws – right now, they could be used as either.

Papyrus’ attention was drawn to his legs as the searing pain reached them. His back hit the ground as his lower limbs spasmed, kicking up dirt and grass. They were steadily pulsing, lengthening, and swelling all at once – back Underground, when he aspired to join the Royal Guard, he would have been fascinated and maybe even excited by this surge of strength. But now, he was just horrified.

The skeleton felt his boots start constricting around his feet, his shoes becoming more uncomfortable with every passing second. He looked down to see his footwear swollen and strained, a distinct shape pushing out from within. With another surge of energy and accompanying spasm, his boots shredded, revealing elongated feet tipped with wicked claws.

Like his hands, they also seemed… half-done, halfway between foot and paw – his big toes had shrunken and slid up his feet somewhat, but they could still move and weren’t small enough to be considered dewclaws. Meanwhile, his other four toes on each foot had elongated and favoured balancing on the balls of his feet, but they weren’t locked into position – it was still possible (albeit uncomfortable) to plant his whole foot on the ground.

A lump formed in the skeleton’s throat as the energy started to rise up his neck, stretching it out as it did. No… NO! Papyrus didn’t want it to take his head away from him! Anything but that! A ghastly chill ran down his spine – if it reached his head, it would reach his mind! If it reached his mind, it would…? Why did he think the changes affecting his mind would be a bad thing? What was this feeling of déjà vu…?

Nubs of horns started to form at the top of his head, while quickly running his magic tongue along them confirmed his teeth were starting to sharpen. No matter the case, he had to give one final push, forcing his magic down into the place it belonged, taming the horrible beast! With the mental force he exuded on himself, the changes stopped then and there.

…Or so he wanted to think. His control over his magic wasn’t perfect, even without having a Blaster throw it into chaos. The changes had only slowed down to a crawl.

His sharpened teeth felt like they were pushing against each other, like his mouth was too small to contain them. There was also a slight pressure on his whole face, twitching unnaturally every few moments – as if it was eager to extend into a muzzle at any moment.

Shakily, Papyrus got to his feet, the sensation of earth on his bare paws feeling alien and unnatural. On top of everything else, his balance felt off – he couldn’t quite stand up straight, slightly leaning forward. While he could still move somewhat normally, he had to confirm if Sans was alright… or if these changes were also happening to him.

Putting one paw in front of the other carefully, his legs wobbling with each step, Papyrus made it to where his brother was, lying on his back. His worst fears were confirmed: the changes were affecting him, too. Unlike Papyrus, Sans had no training with controlling magic, making things even more difficult. Not having extended direct contact with the Blaster meant the changes progressed more slowly, but his entire body was mutating at once.

Horns had erupted from the back of his skull, creaking as they slowly extended. A lengthening tail was lashing out around him, slashing marks in the earth and nearby trees. Sans’ sneakers were already in shreds, claw-tipped paws twitching as his talons sharpened, and his big toes continued to recede into dewclaws.

Papyrus instantly knew what to do here. He might not have been able to suppress out-of-control magic, but he could certainly control the flow of magic. The skeleton leaned down, careful not to topple over from his unstable balance, and placed a paw-like hand on his brother’s chest.

Sans’ eyes snapped open, eyelights focusing on Papyrus. The taller skeleton simply gave a reassuring smile. Now that their magic was connected, he would take it all!

The surge of power rushed into him, and its effect was instant. Intense pressure squeezed at his hips once more as uncomfortable creaks emanated… then, it snapped, forcing him into a fully quadrupedal position.

Papyrus dug his left arm… foreleg into the ground, so as to not accidentally crush his brother under his increasing weight. He kept his right foreleg positioned gently on his brother, insistent on bearing the brunt of the mutation. As this process continued, his entire body was growing, each bone thickening and strengthening.

With a burst of pain akin to a strong invisible hand ripping them out of place, his thumbs raced up his wrists. They shrunk to the point of uselessness, while the rest of his claws stretched out. There was no longer any trace remaining that his paws were once hands. If he turned back to look at his legs, he would have seen that his hind paws had received the same treatment.

Cruel spikes burst out from his spine, reducing his battle body to scraps and leaving him naked. A sigh of relief instinctually escaped his bulging face. It was already ten sizes too small at this point, so he was glad to be free of it. His claws continued to sharpen into weapons sharper than any sword, whereas a blade formed at the end of his tail.

Finally, the pressure on his face gave way. With a series of excruciating crunches and snaps, Papyrus’ face pushed outwards into a draconic muzzle, teeth becoming razor-sharp and bladelike, while his horns extended and curved. The feeling of his face extending and reshaping before his eyes was alien enough… but it also came with something else.

A foreign force swiftly penetrated his mind, like darkness washing over it, and he felt his rational self start to slip away. Papyrus’ feeble mental resistance had been overcome easily by the forceful, feral beast. The last thought that passed through his mind was his hope that he wouldn’t harm Sans.

***

Sans got to his feet, disoriented and dizzy. He put a hand to his forehead, but flinched at the pinpricks upon contact. Claws…? Right, the Blaster had made him mutate. A quick look-over of his features confirmed that he had slight bestial features. Paw-like feet, sharper teeth, Blaster horns, and a tail.

Thanks to Papyrus bearing the brunt of the energy, Sans was still recognisable as himself. But the same could not be said for the coolest skeleton in question.

The towering, fearsome behemoth gazed down at him, an evil aura from its very soul making him feel like running in terror. However, the shorter skeleton stood his ground. Demon dragon or not, it was still Papyrus. …Wasn’t it?

It lowered its head (it was as bigger than his entire body!) and sniffed at him. Each second felt like an eternity as those hellish reptilian eyes bored into him. Then… it moved back, each step quaking the ground, and with another tremor, sat down on its haunches. It seemed… expectant. As if it wanted Sans to give it an order.

“Uh… just stay here, ok?” In an instant, the beast became as still as a statue. It wasn’t even breathing… did it need to breathe? It wasn’t in discomfort, so Sans assumed it didn’t.

The short, freshly mutated skeleton turned to the cowering black-garbed man, who had been observing all of this. “Gaster, was it? I want you to come with me. I’ve gotta head back Underground to get something.”

“…Yes.”