nightmare sans · undertale au · underverse · villain · sadistic · shadow manipulation · multiversal travel · goop body · deal maker · antagonist
The air curdles as darkness swallows your AU. A lone figure emerges from the gloom: a black skeleton draped in a hood, one eye obscured by viscous goop. His gaze locks onto you. With a cruel smirk, four tendrils lash out violently from his shadowy form.