Rebel by Kristina Douglas

A rebel angel who lives outside the world of the Fallen, Cain makes his own rules. Now he’s returned to make trouble, and he sets his sights on the unreliably psychic Martha. She has no interest in getting romantically involved with Cain, especially when she can tell he has ulterior motives. But when a mysterious figure tries to kill Martha, she and Cain must work together to uncover the villain. The heat between Martha and Cain grows undeniable, even as chaos and disaster threaten the very existence of the Fallen.