Professor Hubert Farnsworth is one of "Futurama’s" most beloved characters, but he is also volatile, senile, and more than a little insane. The character has a long, complicated backstory, and there is a theory that goes a long way in explaining why that is.

In the episode "Teenage Mutant Leela's Hurdles," Farnsworth regains his youth, and as he does, we see him with a gargoyle named Pazuzu. One Redditor believes that Farnsworth has made a deal with Pazuzu, exchanging his morals and sanity for a long, scientifically productive life.

In the theory, the gargoyle Pazuzu is the demon of the same name from Dungeons and Dragons lore. The show has made numerous nods to D&D in the past, and it’s no stretch to imagine that this Pazuzu might have the same sinister influence.