My wicked enemy - Carolyn Jewel

Carson Phillip's life was turned upside down when she saw reclusive scholar Alvaro Magellan, an authority on ancient demon mythology and artifacts, commit a murder that was almost inhumane. Magellan raised Carson after her parents died and tried to help her through her debilitating headaches, a condition that made her just as reclusive as Magellan. Carson fears that his beliefs have caused him to lose it and she may be next, so she takes off but something is following her.
Nikodemus, one of the most dangerous ancient demons, is after her. He is on a mission to kill both Magellan and Carson, who has been deemed a witch. But is she really? Carson is beginning to learn new things about herself and being classified as a witch makes sense to her. Nikodemus catches her and reveals that Magellan was only using her for her magical powers and has been killing demons to gain power and immortality and he is now after Nikodemus.
Stunned, Carson doesn't know who to trust, but she knows that Magellan must be stopped.
Nikodemus vows to help Carson learn and control her powers, all the while beginning a steamy romance.