He is voiced by Ron Funches, who also played King Shark in Harley Quinn.
The Fool was staked by Marceline Abadeer to protect the last remaining humans. He is the first vampire Marceline encountered. He used to have two teeth until he lost one to a box turtle. Marceline encountered him in a van and easily defeated him, sucked his soul and gained his power of levitation. He claimed Marceline's hunt for the vampires was a game of hide and seek.
He returned after Princess Bubblegum drained Marceline's vampire essence. He was happy to be alive again and have two teeth in his mouth again. But the Vampire King grabbed him and sucked out one of them, telling him to get used to a new life. He stayed with the King while the others went different ways. When Marceline started to look for the vampires again, she followed the scent to a chamber and finds booth the Fool and the Vampire King. When she rejects the King's "friendship" she grabs the Fool and squeezes him until he dies and sucks his soul, regaining his power of levitation. He shrugs of being stabbed in his usual carefree fashion.
- Levitation- This is the Fool's only known power which allows him to just simply float and fly.
- He is named after the unnumbered trump or Major Arcana card in traditional Tarot decks. The Fool card represents innocence, spontaneity, and free-spiritedness. Similarly, Fool behaves like an incautious, carefree child. In the reversed position, the card can represent recklessness or a disregard obvious dangers, which is what leads to the eponymous vampire's downfall.
- The Fool can play the Bongo.
- Jake describes him looking as if "a baby snake was a baby baby".
- He is the only vampire not to be encountered by Finn and Bonnibel, as well as the only vampire to stay with the Vampire King.