"i'm gonna have a great time."
-Sans before battle

Sans is the main antagonist of the Underfell AU and the brother of Papyrus, and takes on a similar appearance to the Sans of Undertale. He is pushed around by his brother, Papyrus, being forced to call him 'boss' all the time and enjoys inflicting pain on others.

Well, now we have the edgy one. More to come still!