Lore by Alexandra Bracken

Every seven years, the Agon begins. As punishment for a past rebellion, nine Greek gods are forced to walk the earth as mortals, hunted by the descendants of ancient bloodlines, all eager to kill a god and seize their divine power and immortality.
Long ago, Lore Perseous fled that brutal world in the wake of her family's sadistic murder by a rival line, turning her back on the hunt's promises of eternal glory. For years she's pushed away any thought of revenge against the man--now a god--responsible for their deaths.

Yet as the next hunt dawns over New York City, two participants seek out her help: Castor, a childhood friend of Lore believed long dead, and a gravely wounded Athena, among the last of the original gods.

The goddess offers an alliance against their mutual enemy and, at last, a way for Lore to leave the Agon behind forever. But Lore's decision to bind her fate to Athena's and rejoin the hunt will come at a deadly cost--and still may not be enough to stop the rise of a new god with the power to bring humanity to its knees.