This is just what i think the papyrus battle would be like after you kill Sans. Everything is in the view of Frisk. I just thought i would metion that.
You walk into the hall of judgement. You immediately saved before starting to walk down the corridor. You expected there to be nobody. But instead, standing there, was Papyrus. He wore Sans' blue jacket underneath his scarf which was wrapped around his neck.
" Human. I had belief in you. I trusted you. I thought you could change. I used to think that even the worst people could change. Now after what you've done to my brother, I no longer think that. " Papyrus tells you. You just want him to stop talking. You want him to stop breathing. You want him to die. Immediately, you run straight towards Papyrus. He summons bones from the ground in your path, killing you immediately.
You respawn and come back into the hall of judgement.
" Sans' would've said that you're gonna have a bad time. Instead, im going to have a great time. " Papyrus tells you before summoning a series of bones and gaster blasters. You manage to survive this attack. You try to strike him with your toy knife but he moves at the last second. Papyrus had summoned a gaster blaster behind him as you were running at him, so when he moved you would be hit by its blaster.
The cycle continues on until you die so many times you loose count. Papyrus is showing no signs of exhaustion so you start to think that he's impossible to beat. He even does different attacks in different orders every time. You try to memorize them all, but it seems that Papyrus keeps on making new attacks up.
" Human, don't you realise that were stuck in a never ending battle. It's practically impossible to beat me, so just RESET. It would be the smarter option. Please, RESET and spare everyone. " Papyrus begs you. You decide to try and attack him while he seems distracted. He quickly summons bones from the ground in front of him, like he did the first time you tried to attack him.
" I guess not then. " Papyrus whispers to himself. You appear back in the hall again, except that this time you save then summon up the RESET button.
" I guess i was wrong, you are going to reset. " you hear Papyrus whisper in a happy tone. You press your hand down on the RESET button and it glows yellow. Everything fades to black, then you find yourself in the bed of golden flowers again.
This was just a quick story, but i can write another chapter explaining a whole story in which Frisk kills Sans before the hall of judgement.