The Chronicles of Chrestomanci

In the multiple parallel universes of the Twelve Related Worlds, only an enchanter with nine lives is powerful enough to control the rampant misuse of magic-and to hold the title Chrestomanci. . . . Cat and Christopher Chant make the most unusual friends. Christopher befriends a boy with terrible karma in a mansion where everything keeps changing. Cat meets a girl whose family of rogue witches is hiding shocking secrets. Will the Chrestomanci be able to sort out the tangle of mysteries and magic?