Back Underground (Sans X Reader)
THE THIRD AND FINAL BOOK!
Sans has to return and ends up losing you along the way. You are lost, alone and comfused, trying to find your skeleton lover in the Underground.
Another human has fallen. Sans is assisting your brother Frisk in getting around the Underground. Papyrus is back, acting as if nothing has happened, as is Undyne. How will this go down?
(Also, I'm sorry everyone who thinks differently, but in this fan fic, Frisk is a boy. I know that Frisk is gender neutral, but you know.)