Sans was unsure why the house was so quiet. Sure, the others were out and about, but Frisk was still here and Chara should have been back by now. Going to the living room, Sans was surprised that Frisk wasn't on the couch playing on their Xbox. They usually loved to play Minecraft, especially with Chara. Sans had an epic prank for them, so he decided to go see if he can find them.
"Where are ya, kid?" he called out. He was to lazy to go actively searching for them, so he just waited for the sounds of their footsteps to come down the stairs or around a corner. But it didn't happen.
"Frisk, come here, I got something I wanna show you!" This time he called out louder. 'Maybe they didn't hear me the first time?' he thought. But after a few minutes of nothing, he started to get concerned. Frisk never took this long to come when he called. So, the obvious thing he did was go check the bathroom to see if they were in there and couldn't get out at the moment.
He hoped and prayed that this was the case as he knocked on the door.
"Hey, kiddo, you in there?" After a wait with no answer, not even a grunt, he tried the doorknob. It was unlocked, and he pushed the door open. He didn't find them in there, and now he was worried.
"C'mon, Frisk, this isn't funny!" He started checking every room, searching for them, but didn't find them. At this point he was panicking. He actually started running from door to door, checking the rooms. He even checked the rooms that didn't have anything in them. At the last door, he saw the door was open. When he peaked inside, his non existent heart stopped.
Frisk was there, nailed to the wall with their stomach cut clean open, their limbs missing, and their eyes shut. Sans still had his usual smile on his face, but his eye lights had disappeared. Surely what he was seeing couldn't be real, right? Frisk couldn't be dead. Frisk couldn't die. They could RESET. They would just LOAD their save file if they died, right? Sans walked up to Frisk's body and got on his knees.
"Hey...Kiddo...You can stop playing around now...RESET already..." Sans waited for the normal shift in the space-time continuum, but it didn't happen. Sans's smile started to falter.
"Frisk...RESET...Just RESET..." Still there was no RESET. The Timeline continued on with no interruptions. Sans had now lost his smile completely.
"I have to find Chara. If Chara is still here, then they're still alive."
Sans put his hand on the ground to push himself up, but he felt something smooth on the ground. Looking at his own hand, he saw dust. Chara's dust. He looked at Frisk again, and saw dust covering their entire body.
"No..." Sans couldn't believe that Frisk was really dead. He wouldn't believe it.
"Frisk...RESET...RESET! RESET NOW GODDAMN IT!" Still, there was no RESET.
Magical blue tears rolled out of the skeleton's eye sockets. There was no way this was happening.
"FRISK, I KNOW YOU CAN HEAR ME! STOP FUCKING AROUND AND JUST RESET! LOAD, RESET, HELL, EVEN DO A TRUE RESET, I DON'T CARE! JUST RESET!" But no matter how much Sans screamed at them, Frisk couldn't RESET. They were truly dead this time. There was no do over this time around.
"RESET!" Sans was now sobbing, starting to accept the fact that Frisk was gone forever.
"Reset! Reset...Reset...Frisk...Please...Don't go...Please..." Sans used his Blue Magic to remove the nails in Frisk's stumps, and began to cradle their head in his arms.
"Please...Don't leave...Don't go..." No matter how much Sans pleaded, Frisk was gone. There was nothing that could be done to save them. Frisk and Chara were now gone for good. Even as Sans accepted this, he still held the small child in his arms. He didn't want to let go of his friend. Even though they had been through rough times. Even though they had done the Genocide run so many times. Sans eventually forgave them for that. They became genuine friends again, like in the first timeline Frisk ever went through.
He still remembered the smile and the laughter of Frisk after his whoopie cushion handshake trick the first time around. As Sans held Frisk's dead body in his arms, he began to remember the first ever timeline. It was a neutral timeline, since obviously, Frisk had no idea what to do to get the true pacifist. He remembered taking them to Grillby's for the first time, trying to sell them that fried snow, stacking those hot dogs on their head, and even taking them on that date to Mettatons restaurant.
Then he started to remember the timelines after that. It took a few tries, but they eventually got the true pacifist. Sans remembered when Flowey grabbed them all and started attacking Frisk. He regretted not jumping in to help. He could have easily taken a shortcut out of those vines and helped them, but he was to lazy. Sans began to regret every moment of not helping Frisk. From when Flowey attacked, to when Undyne attacked. He should have been their for them. He shouldn't have been so lazy. He should have cared more. He should have cared enough to stay at home and watch Frisk while the others were out and about like he should have instead of going out to put whoopie cushions on every seat in McDonalds. Maybe then he could have stopped this from happening. If only he cared more.
But now, it was to late. What was done was done. Frisk was gone forever. And Sans had to live with the fact that it was all his fault. Sans continued to hold Frisk's dead body, staying still on his knees for hours. Even after the family got home and even after the police took Frisk's dead body away, he stayed on his knees. After the funeral, Sans stayed at the graveyard. He got on his knees in front of the tombstone, and stayed there. He would never leave his friend again. Even if he had to stay with them for all eternity. After all, graveyards is where skeletons are meant to be, right? And now, that's exactly where Sans was. In the graveyard, with his best friend. A friend he would never leave again.