Jealousy - A Sans x Fem!Reader

Sans had gone through a ton of runs. He had started to trust Frisk, as they had never done a genocide run. It had always been True Pacifist, then a reset. He was tired of it, but happy to know the kid would never kill anyone. But then, something different happened. Frisk had made it to King Asgore, but had gone back. Something was different. Something wasn't right.

this was inspired by ZanaBSparrows!!

characters, places, and undertale are by toby fox and temmie chang, not me! you probably know that, but i dont want to be sued or smth

notes!
Y/N: your name
E/C: eye colour
S/C: skin colour
F/C: favourite colour
A/N: author's note