The Wanted Child (Chaos Gods Book 1) by Aneeka Richins

ALL SHE WANTED WAS A HAPPY ENDING. Fifteen-year-old Ki doesn't care what half of the nine gods say. She will not let her parents die to save the Four Lands. Tavk, the trickster god, agrees to protect her parents as long as she completes his missions. For the promise of a happy ever after, Ki evolves into an infamous demonic fighter and tries to ignore her fading humanity and growing loneliness. Then she meets De: the gods' new Hero. The gods need him trained fast and Tavk is only too happy to sign her up for the job. Two years older -- and distractingly handsome -- De practically worships Ki and wants to be both her best trainee and her best friend. But he doesn't know who she really is: The Wanted Child. The one the new Hero, De, is destined to kill so the gods can finally destroy her parents.