Dark’s past is very secretive, meaning that not much is known about him. What is known is that he was a phantom thief and he is one half of the Artwork The Black Wings. His nemesis Krad is the other side. He slumbered for 40 years and finally woke up in Daisuke Niwa. He could care less about the human he is possessing at times, but later comes to actually care about him.
He is great at stealing art, lock picking, disguises, and evading traps. He is the perfect thief. He also has the ability to use magic through black feathers. He uses this ability to unlock the powers of artworks the Niwa family has him take. He can fly by transforming his partner With (or Wiz in the manga) into wings. If he did use his real wings, Daisuke would be in a lot of pain.