Mahmoud Saleh was once a doctor, but becomes an ice cream maker after his wife and daughter die and he moves to New York. Oh yeah, he's also possessed by an ifrit (like a subspecies of jinni) and can't look people in the face without going crazy. His favorite ice cream flavor must be Hazed & Confused.
Our little saddest ice cream maker in the world is a minor character who ends up having quite an impact on the story by the end of the novel. He's one of the first people to recognize the Jinni as something other than human, and he becomes obsessed with this, following him around trying to figure out why he can see him.
Along the way, he crosses paths with the evil Yehudah Schaalman (who is also tracking the Jinni) and Schaalman ends up entering Saleh's mind without asking or getting permission. He digs in Saleh's brain and violates his memories, which is totally uncool, but oddly, this also cures Saleh of his possession. He ends up sacrificing himself in the end to save the Jinni. Thanks, Saleh.