A/N: this is a crossover fanfiction based off of game theory's video on sans. If you do not tolerate this theory I suggest you avoid this story without any comment. Frisk, the eighth human to fall into the Underground, had decided not to fight Asgore and return to the surface. But instead to stay with the skeleton brothers Papyrus and Sans, who have become like family to her. Everything seems peaceful, that is, until Frisk begins to find out more about Sans than she ever thought she could. And catches glimpses of the man who speaks in hands... Also on fanfiction!:https://www.fanfiction.net/s/12104792/1/Im-Still-Here-An-UndertaleEarthbound-Fanfic

Sans has a good life. A caring father, an adorable baby brother. Things couldn't have looked better. But soon after the two started school in snowdin with the other monsters instead of being home schooled, disaster strikes. Will Sans be able to get through this newfound relization unscathed? This story goes by the theory that gaster is the father of papyrus and sans. Though the theory is incomplete since no one knows who the mother is. For all we know sans and papyrus could have been made in Gaster ' s lab since they just "appeared one day" No one really knows, but it's fun to debate about. Enjoy

When Frisk finds out one of the Bone Brothers are ticklish and tells the other, it starts out an entire hunt to see how far they can survive 'til they meet their tickle-filled demise!