Chapter Text
Dust scattered in the wind as the beast walked down the street, pink eyes glinting with malice as it approached the last of the skeletons. Finally. One last nuisance to be rid of, then it could finally finish what it started centuries ago. He had his back turned. Perfect. It sped up to a run before leaping at him, its arms reforming into sharp points, waiting for the moment of satisfaction when the hit landed and the helpless creature crumbled...
But it didn't come. The only thing its arm made contact with was a hard, smooth wall of magic. The beast scowled and struck the barrier again, attempting to break it down and stamp out this pathetic rebellion, but it refused to even crack. It tried firing its pointed bullets at it, but still the barrier stood there, barely even a scratch. After a few more moments of fruitless attacking, the beast noticed a slight movement. The skeleton had turned to partly face it, showing only his hollow left eyesocket. It smirked to itself for a moment, noticing that he still seemed to be stuck with what he had the last time they fought.
The seven skeletal hands that materialised under the two larger ones made that smirk falter.
The crimson pupil that flickered to life in Gaster's left socket and the distorted dying screech of its main magic source was what wiped it clean off.
He heard the formless creature screech as it hit the ground in the distance. He noticed the silence in that direction that came soon after, too. His best guess was that someone had managed to destroy it. However, that was not his priority at the moment. His gaze did not move from the beast in front of him, just behind that barrier. For once, it stood perfectly still. It had shifted drastically from its human form, no longer recognisable as human or monster. Of course, it was neither and had always been that way. Perhaps once the vessel it resided in had been a human, but they had died a long time ago. The smirk that had been on its "face" a few moments before had fallen, replaced by a look of...uncertainty? Concern? Fear, perhaps? The idea amused him. The one who had struck fear into the hearts of everyone involved in this mess was finally beginning to understand what that felt like. He stared at it a few seconds longer before putting down the barrier in front of him, replacing it with one that surrounded both of them. The last thing this city needed was more destruction. This way, only it and himself would be destroyed.
He never did like collateral damage.
The two fought for a while, their attacks becoming a blur, the barrier cracking and splintering as Gaster's focus faded, the crimson flickering at the edges of his vision, inviting him to just let the world around him disappear. He knew that he was running out of time before he slipped and lost his grip. Narrowly dodging a swipe from the beast's claws, he sighed to himself. Eight of the hands flashed crimson, only one of the smaller ones remaining green to keep the barrier in place. The damage from the eight combined should be enough, but he wanted to completely destroy this beast. It would be quite a strain, but in a matter of moments, that would no longer be a problem. The smaller hands disappeared, replaced by five larger ones. One continued to hold up the barrier, but six of these should certainly give it hell. The attack charged as his energy rapidly drained. He never had liked to push his magic this far, but in the state he was in now, it was worse. He stared at the beast in front of him, which had frozen with an expression not too different from a deer in headlights. He considered saying something, a farewell perhaps, but there was no time. Both he and it were knocked into the walls of the small bubble he had trapped them in as light consumed everything inside, feeling almost as if it was tearing him limb from limb. And yet he still stayed fully aware, would not let himself rest yet. He had to see it die, watch its form crumble first. He was determined to see this end.
The light faded as all seven hands shattered, unable to remain stable any longer. Crimson pupils faded back to a dull silver as they flickered. He was struggling to stay conscious, searching desperately for any sign of his opponent until his gaze rested upon a shapeless, sickening pink form. It twitched slightly as he slowly rose to his feet, something vaguely resembling a hand reaching out and trying to grab at him, hissing promises of his demise in a gurgling, almost pitiful tone. He glared down at it as it began to writhe more violently, focusing with what little he had left and making one final skull materialise beside him. Its form blurred and glitched, ready to fall apart at any moment, but it would do. The skull whined quietly as the light built up between its jaws, alternating between red and white. The beast...no, not a beast anymore. The creature growled, a sharp spike reaching out from its form, attempting to grip at his soul and reform itself again...but it never made it. With a final flash of red, all that remained of it was a pink stain on the ground. The Black Beast had finally been slain.
Gaster stumbled, falling to the ground. With the goal he had been so determined to reach completed, he had no reason to stay here. The skull vanished, leaving him to kneel alone in the street. For the first time in what felt like an eternity, he felt satisfied. Complete. He had succeeded, done something that hadn't hurt anyone else. He chuckled, wincing at the pain the simple action brought, but smiling nonetheless. The blackness slowly closing in felt welcome. It relieved him.
This was all he'd wanted this whole time.
Some rest.
For the first time since his eldest son died, Gaster's mind was quiet as the darkness surrounded him. All he heard was one thought, completely his own:
"You'll all be fine without me.
I promise."