Walton was a living wallpaper on the west wall of the Doyles's penthouse apartment.
He was a man, but was flayed alive and turned into wallpaper for sleeping with the wife of a man he was in a secret society with (The Triangle Club). His punishment was to be a punishment, and he was sent to the Doyles to drain their souls, but upon installation in their apartment he was too charmed by them to cause them any harm,
Aside from soul-draining, he also has the ability to cast out his consciousness into the world to locate specific people.
Walton is played by Rob Benedict.