You dirty killer. It was another genocide run, you killed Asgore and came toward the spot where you would've met Sans, but you met Papyrus instead.

"...let's get to the point."

After struggle and struggle, you beat him, down to his final bone, he dusted after that. But before he died completely, he said something.

"sans... i wish you the best..."

(fast forward)

Acknowledging his brother's death, he swore to kill you, no longer trusting. When you arrive at Judgement Hall, you see Sans, with his brother's jacket around his waist, and a long bone.

"you... why? why did you kill him? he didn't do anything. we could've been friends. we could've gotten a good ending... you dirty brother killer."

BATTLE, START!