Abdalin was once a legendary thief king in Egypt, and was close friends with William Timerus. After they survived the plagues, Abdalin gave William control of the thieves guild. When William became the Game Master, Abdalin joined him as the Black Joker. He served the Game Master loyally until O'Zalia killed him. Abdalin then dropped off the radar for a while, supposedly due to depression at the loss of his closest friend. Daniel Ferris eventually began seeking out his help in resisting The Fears, and he agreed after some persuading.
Abdalin's true form is unknown, as he is able to alter his appearance gradually over time. His current form is that of a dark haired teenager in a trench coat, as seen in this video.
He claims to have taken this form to get a fresh start.
Weapons and Powers
As the Black Joker, Abdalin was equipped with a Game Mask, a deck of magic tarot cards, and a two foot long iron rod for close quarters. However, he destroyed all of them sometime after the Game Master's death. It is unknown if he has any other weapons.
As a Joker, he possesses abilities of the other suits, including enhanced fighting prowess (the Spades), high intellect and calculative skill (the Clubs), and healing powers (the Hearts). Although his powers aren't as strong as the other suits, his ability to use all of them gives him some advantages.