Underswap Sans, ULCFan Wiki

Underswap is an AU where many of the characters' roles are swapped, as well as their personalities, though some quirks tend to stick in places, or are modified. Sans is the excitable, confident, extremely optimistic human hunter, while Papyrus is the laid back, protective bro following Chara

Underswap: Fallen Under] sans. by NewAbyssiniaDraw4521 on DeviantArt

Sans, TS!Underswap Wiki

Sans/Underswap, New Undertale Fanon AU Wiki

Underswap Cast by flambeworm370 on DeviantArt

Underswap Sans (Canon), Wiki

Underswap Classic: Sans Fight! by Robby_Studio - Game Jolt

UnderSwap Sans, Wiki

Underswap, Underswap Wikia

Sans/Underswap, New Undertale Fanon AU Wiki