Hound and Key

Key has lived her entire life in captivity, forced to use her magic to kill the enemies of Ariadne, an ageless woman with powerful magic of her own. Key knows she and Ariadne are both members of the Hand of the Gods, five souls reborn through the ages, but Key remembers none of her past lives. She chafes against Ariadne's control, and longs to escape to lead a life of her own. Eric has worked for Ariadne for years in ignorance of her secrets, but now coincidences and bad luck are piling up.
When he talks his way into the compound that houses Key and the other members of the Hand, he learns the truth about Ariadne's magic-and the murders she's committed with it. Together, Eric and Key escape and set out to find Lantern, the one member of the Hand Ariadne has never managed to capture-and who may know how to stop her for good.