Shadow in the Ember, by Jennifer L. Armentrout

Shadow in the Ember is the first book in Jennifer L. Armentrout’s suspenseful, action-packed fantasy series Flesh and Fire, a prequel to the Blood and Ash series. In Shadow in the Ember, a prophecy guides heroine Saraphena Mierel throughout her life, as she is destined to strike down the Primal of Death after becoming his consort. However, as she gets to know her target and the realm of the Primals and gods, she realizes that not everything is as it seems. Can Seraphena save her world and become her own person, or will she forever be a puppet for the Fates?