Nightmare is a 32 year old History teacher who teaches at Underhigh. He is good friends with the Librarian of Underhigh, Goth, and the Cheerleading captain and Goth's boyfriend, Palette. He used to be in a relationship with the therapist of Underhigh, Muffet, though they broke their relationship off for reasons unknown to the school, and they don't talk anymore. He has a son named Incubux. He's also friends with the gym teacher of Underhigh, Error.