[Undertale] Sans X Reader - Repeat, Eternally

Prologue- Repeated

[Above is legit a feeltrain so just listen to it.]

Reliving the same three seconds of your life over and over again tends to get really tiring.

All you can do is think of happy times, like when you first met the punny skeleton.

You had come before Frisk, but in another time line. The ruins were not where you had fallen, but you instead had walked through Asgore's castle.

Right through.

It was as if nobody was there, even while walking through the city in which monsters should have recognized humans.

It was too easy.

Sans widened his eyes for the 67,753th time.

That expression still broke your heart.

The location was the Hall of Judgement.

Before you was Frisk, no, Chara.

Before you was a true monster.

Sans hadn't been able to save anyone. Chara only reset the timeline over and over.

A simple touch of a button.

Your determination was unstable; you had none, due to serious self-hatred. You tended to inflict upon yourself emotional cruelty; you brought yourself down in every aspect.

The knife in Chara's hands plunged through your chest. It slid in easily, as if it was being welcomed home. A gasp escaped your lips as Chara removed it, and jumped backwards. Blood stained your clothing, and everything went black.

You pushed yourself off the wall again, and the same scene repeated over.

Why were you here?

That's right, you remembered. This is what happens to those who couldn't reset along with the others.

This is the fate of the monsters and humans who didn't make it through the reset.

Living through their final moments, over and over.

Inside yourself, you laughed bitterly. If Sans thought he had it bad, just wait until he stops making it through the resets.

No, you couldn't think like that. That was terrible and wrong. You are the one who gave your life to save Sans. Sans didn't force you to do any of this

You wished Papyrus wouldn't have died in this timeline.

You'd eat an entire world full of his spaghetti just to see them all again.

Just to be able to reset with them.

You were at 70,000. New record. Of course, the number would never go down.

You pushed off the wall again, but Chara had stopped completely. This was different than last time.

Different than the last 70,000 times.

You heard it before you saw it.

"W.D... Gaster..." You whispered, the first words you'd spoken in 70,000 deaths.

[So you know of me?] He asked, in Windings. [And you know of the darkness.]

You didn't quite understand his last comment, but you nodded anyways. It was painful, to move differently.

"Heh, if it doesn't work the first time... just try, 70,000 more times..." You took a wobbly step forwards, unused to any other path except for the one that you took to protect Sans.

[I will get straight to the point.] Gaster's signals were going so fast that it was getting hard to read them beyond his distorted voice. [I can help you leave this endless fate.]

"W-what?" You tripped over your words. Freedom sounded delicious.

[However, freedom comes with a cost.]

The pause from Gaster made your soul tremble and your knees shake. You didn't say a thing.

[You're going to put an end to the mistake that was my own.] The distortion slowed, and so did his signals. [However, as good as that seems, there are certain conditions.]

"Please tell me."

[If I save you, your soul will be bound to the Underworld. If you get the barrier down, you're not going to be able to leave. You're never going to see the sky again.] Gaster's shoulders hung low; he had been through the same song and dance plenty of times.

"Hell, that's good enough for me." You laughed weakly. "Just... saving them all is good enough for me. I'll just die after, right?"

[... I'm sorry.] Gaster moved his head from side to side. [The only thing able to reset after the cycle breaks will be you. And even if you do manage to pull it off.... you'll dissappear like a monster would, with no room for rebirth or second chances. ]

"I...I see..."

Both of you remained silent.

"Can you promise me that it will work?"

[What?]

"What is one human's life compared to the lives of countless others? I'm down for this. Hey, I can have a good time with my friends while they're still here. I can be a BONE-afide friend." You borrowed one of Sans' jokes, which caused a reaction from Gaster. He began to laugh deeply.

[Unfortunately, there is another roadblock. You will not remember this Timeline. Your DETERMINATION is broken. The most you can remember... is a single word.] Gaster put his thin, skeletal hands together as if praying. [Please, take your time with choosing this word. It may be able to help you in the next world.]

You wrapped your arms around yourself, and exhaled. A word that would help you.... and you found it.

"I...know what word I want to keep."

[Are you sure?] Gaster pressed.

"I'm positive."

[I am going to save you now. Please summon whatever DETERMINATION you have left, and keep the word close to your soul. If you don't, then you will lose that word forever.]

"I've got it."

You prepared yourself, but all Gaster did was snap his fingers. One of his eyes shined blue, while the other was ringed in yellow.

You could feel his DETERMINATION.

It was heart-shattering.

You smiled one last time, before falling into the sky of the Underworld.