Peter D. Bellone The Id Idiot

The book is about Stephen Fairfeld and get this: a black bagpipe player Theo Phrastus who believes he is possessed by a 19th century Irishman. The book is divided into three parts. Since the Title is The Id Idiot maybe this corresponds with Freud's three sections of the psyche, id, ego, superego; I don't know. In the first section, Stephen falls under the spell of Billy, a drug dealer/painter. Stephen burns down a bar for him and later on flees the city, which brings us to part 2. Theo and Stephen end up joing this cult and becoming born again Christians. Stephen channels his madness into religious fervor and gets on the bad side of the leader Brother Barnabas. They leave with a woman and the three of them end up opening a homeless shelter and it falls apart at the end. I don't want to give away the ending, but it's amazing.