The Demon's Lexicon (Demon's Lexicon Trilogy, Bk. 1)

Sixteen-year-old Nick and his brother, Alan, are always ready to run. Their father is dead, and their mother is crazy - she screams if Nick gets near her. She's no help in protecting any of them from the deadly magicians who use demons to work their magic. The magicians want a charm that Nick's mother stole - and they want it badly enough to kill. Alan is Nick's partner in demon slaying and the only person he trusts in the world. So things get very scary and very complicated when Nick begins to suspect that everything Alan has told him about their father, their mother, their past, and what they are doing is a complete lie. . . .