Take a Thief (Valdemar)

Skif was an orphan who would have died from malnutrition and exposure if he had never met Deke the pickpocket.  By the time he was twelve, Skif was an accomplished cat burglar.  But it wasn't until he decided to steal a finely tacked-out white horse, which was, oddly enough, standing unattended in the street, that this young thief discovered that the tables could turn on him--and that he himself could be stolen!