Well, this is my first fanfiction ever, so its bad, also, sorry about my english. My native language is Spanish, but i don't like it.
Anyway, let's start with it then!
Chapter 1: Why you did this?!
Narrator's POV:
"Agh!" Pain sounds are hear, and a sound of a knife that's swinging around is hearing. Then a calm voice says "You really like to swing that thing around, huh?" A guy with a non-serious tone said. "Welp, looks like it.. Why did you did this?, what is the thing you want?, WHY YOU KILLED EVERYONE?" The same guy said, with his left eye Blue and orange changing, with something that looks like its named "Gaster Blaster", obviously, it blasts things.. In this case, that kid, that kid with a striped shirt, most of it blue, and the lines, with purple. That kid was just holding a knife, trying to kill that guy that wears a blue jacket, a skeleton. That skeleton, more likely a magic-skeleton, was a powerful being, but he was lazy. He then said "Maybe we could be friends again, do you remember me?, do you remember?.." Then, the kid started to cry.. The kid throw they knife out, and started to say "Sorry, sans!, i'm sorry... I'm just going to re-" "AAUGH!" that magic skeleton just killed a kid. Blood was all over the kid and "sans". The kid died, obviously, but then, the kid reappeared in there. Not giving up to it, they'll have like a "revenge". But the kid throw again they knife, and sans killed they again. But something weird happened. That kid appeared in something that says "Continue" or "Reset" The kid was about to press the "Reset" button. But then a black magic "grabbed" the kid's hand, the one who did the magic, it was a weird, without corpse "skeleton" his left eye was almost destroyed due to a crack, and his right eye was perfectly good, he had holes in his hands. That was a weird, looking monster.. Then the monster starts to speak "Are you going to reset, kid?!, you promised me to KILL EVERYONE HERE." Then the kid shouts "NO!, I DIDN'T!. WHY DO YOU WANT TO KILL EVERYONE? POOR MONSTERS. PLEase.. Let me reset..." the kid started to cry, while pressing the "reset" button.
Sans POV

I was waiting that kid.. I waited.. With a Gaster Blaster in my side.. Then, everything went white...

I was in Snowdin again, I thought to myself "Oh thank god, Frisk. You reset.. Please don't kill everyone.."
I waited 3 hours, then something appeared, it was the kid.. I reactioned rapidly, and started to walk with them... I knew the kid was going to turn around, so I teleported everytime whenever they turn around.

They got trapped, in the "same trap". i had to make my job. I teleported behind them, and didn't say anything. I said something weird, i wasn't supposed to say that, but i don't care. I said "Hey kid, so you reset.. You didn't killed Toriel, do you?" then the kid turns around and replies me with a "No" and the kid took a weird form, like a skeleton with holes in their hands, with a crack on their left eye.. then the kid says "BUt i'M gOiNG tO KilL yOU" I scared the hell out of me, then I change the gravity of their souls, and bring them far, far apart, then they teleport infront of me, with a old, damaged Gaster Blaster,I was the only that could summon Gaster Blasters, me, and Gaster, i thought that they were Gaster. I said "No... Gaster, why?!" Then, they hit me...I see a bloody-red thing coming out from my body, that was ketchup, then I close my eyes and I wait to turn to dust... I fall, and I turn sloowly to dust... But then something covers me, and fills me with determination. It was Frisk's soul, I open my eyes, I "exploded" and started to fly, then I summoned like 30 gaster blasters and I blast them, I didn't got tired, that was weird.. Then everything went black, I thought that I faint.. But no, i died.. I can't with determination.. But then, I remember that I have determination.. Enough to reset everything! every single thing!, i push the reset button with all my forces then everything went white, and i appear, in my house, with papyrus.

But I didn't know, it was another timeline.

Wooooooow drama ending! I think this is good for a start...well, you know that this is my first fanfic, but well, hope you liked it! Sorry for my bad English.
Uhm, i think this fanfic will have a bit of romance? like Sans x Frisk or Soriel, meh, i don't know if I should do them. Maybe as friends, well, let's stop talking about it. Well, see ya in the next chapter!
also, my "ocs" or "pjs" are: Vicelt, and Splik, both of them have fire powers and most of their powers are by sans, they both are males and their ages are Vicelt: 12, and Splik: 11 , Well! :D

See ya !