Yandere Underswap Sans x reader [COMPLETE]

You always thought of Sans and how cute he was all the time to his laugh to straight out personality. But things are starting to change, when Sans got in a fight with Papyrus, and your friend Muffet disappeared. Until you discover a dark truth about Sans and his love for you...

This Isn't You. . .{Yandere!Underswap!Sans x reader}

It all started when you fell down that hole. You met a new "father". Some new enemies. Some new friends. It seemed so great, but soon it'll all go downhill. Monsters disappear one by one. It's all because of your best friend. Your crush. The innocent one.