Chibi-Devil

Real Name: Plutus
Species: IMMORAL HELL SPAWN!
Timeline: Party Goers
Year of Birth: As old as time
Residence: The Fourth Circle of Hell and/or someone's shoulder
First Appearance: Party Goers 17
Personality: Thinks he's all that, despite being around the size of your head. He slinks and crawls and whispers evil thoughts into your brain.
Special Abilities: When Chibi-Devil says, "You can say that again," the last person who said something will repeat what he/she just said. He tends to say it a lot, until said person will repeat what he/she said even when he doesn't say it. Only the truly strong-minded (and Masamune) can break out of the spell. He can also climb up someone's back without them feeling it.
Flaws: He hates having to move of his own accord. He's immortal, but hardly invincible, and usually a good thwack can get him off your back... for an hour, anyway.
Friends: None
Enemies: Everyone
Creator: Luigi of the Pipes

History: Chibi-Devil is actually Plutus, a demon appearing in Dante's Inferno (not the Greek god). He was the most pointless demon to stand in Dante's way, as he randomly sprouts gibberish at him and then is knocked out cold by a few words from Virgil.

He first appeared in Party Goers 17, after the Party Goers had descended into Hell in search of a missing piece of Guisseppie. He revealed himself as Luigi of the Pipes's arch-nemesis, though he hasn't done a whole lot to prove it.

Since Party Goers 17, he has made a few other appearances (at the behest of Masamune), usually teaming up with the villain of the moment and doing... nothing.