"so, guess that's it, huh?"
Sans is kneeling on the floor of the Judgement Hall, exhausted from his fight with the human, no, the demon. It walks up to him, ready to swing that killing blow. Sans closes his eyes, hoping it won't be too painful.
There's a small tapping noise. The pain never comes.
Sans opens his eye to watch the demon fighting with...itself? Their right hand, the hand the knife is in, was poised right over Sans. Its left hand though, was holding onto their right arm, preventing the knife from hitting Sans.
"No!" itscreamed. "Frisk! Why are you always so insistent on fight me?! Let me go!"
"Sans," they say, this time their voice calmer. "I'm sorry for what we did. I know there's no way we can possibly make up to you for the things we've done. You deserve a better life than this."
The demon then drives their knife into their own guts. Sans just kneels there, shocked.
The demon's body slowly disintegrates, leaving a shining red heart.
The last human soul.
Sans stands up and dashes forward to cup it into his hands.
You deserve a better life than this.
Sans dashed through the throne room to the barrier. He stood before the unbreakable, shimmering white wall, standing in the center of the ring of capsules holding the other 6 human souls. Sans holds the red soul out in his hands.
The other human souls slowly floated out of their canisters to converge with the red soul in Sans's hands. Suddenly, there was a blinding flash of light. Sans covers his eye sockets as to not get blinded. When the light disappears, he moves his arm to get a better look. The shimmering white wall wasn't there anymore. Sans let out a cheer of joy before grabbing the red scarf around his neck. The joy in his soul was then extinguished by sadness.
He had finally managed to break the barrier, but nobody was alive to enjoy the surface with him. For a second, he considered just staying underground to live out the rest of his years. As a skeleton, he did have a very extended lifespan, but he wasn't immortal. He shook his head.
No. The demon, or whatever was inside the demon, sacrificed itself to give me the opportunity to have a taste of life on the surface. I can't let that go to waste.
Sans took in a deep breath before starting his trek up out of the underground and to the top of the mountain.

YOU ARE READING
Sole Survivor (A Percy Jackson x Undertale Fanfiction)
ActionSans had finally killed the human. He doesn't know why, but they just stopped coming back. He took their soul and, using the other 6 human souls, broke the barrier. Along his way to find a place to stay, he comes across Camp Half-Blood, and there...