Origin
Very little is known about Walter. A former arch-duke of Hell, he left for some unknown reason and moved to New York City. He sought employment with a cat rescue.
Creation
Walter was created by James Tynion IV, Ming Doyle, and Riley Rossmo. He made his first appearance in Constantine: The Hellblazer #6.
Major Story Arcs
The Hellblazer
Walter is attacked by Mister Gobble, the thing living in the basement of his apartment complex, and saved by John Constantine. Later, he orders some food from Oliver.
Powers and Abilities
Walter is a demon, and possesses all of the powers and skills inherent to his race, though he does not appear to be particularly powerful. He is a shape-shifter; the exact limits of his ability are unknown.