The Orphan (Stallman, Robert) 1980

Literary Teen Wolf.  This is a depression-era story about a year in the life of an orphan -- a wild animal of no known species -- that is able to metamorphosize into a human.  This is not simply a change of shape; the human form that he takes has its own thoughts and feelings separate from, and yet tied to, the beast, and it's all a metaphor for how we integrate our human selves with our dark subconsciousnesses.  The novel is really two novellas stitched together; one for each family that he lives with during the year, and for two different stages of life: the first at about 5 years of age, and the second on the cusp of puberty, with all the attendant pre-teen angst.  I think my favorite part was reading about the flirting games I hadn't heard of before: Wink 'em and Post Office, though the game of Post Office played in the book had one person go into a dark place and call out to someone from the other room, who would go into the dark place and, a minute or so later, exchange places with the first person and call out to someone else from the other room to come to the Post Office.