This is an unusual story for me. There are no magic transformations and yet there is magic and there is a physical transformation. It's urban fantasy, I suppose. Sometimes, I wonder about the other version of the story. The one where the demon yields and becomes the son's mother figure. Would he still have possessed the cruel streak he "demon"strates (heh) here? And, at the end of the story, the question is "what does a forty year old man, well-versed in demonology, do with a servile demon?"