GIFT OF FLAME by Beth Hudson
Traumatized by her experiences in a recent war, sixteen-year-old Maelen Saltbearer searches for someone to teach her magic. Due to her single-minded thirst for revenge, no mage has taken her as a student in the past two years, despite her innate talent.
She finds herself on the doorstep of Garmyn, sole mage to the lord of a remote forest hold and town. At first Garmyn is unwilling, but Maelen makes him a proposition; she will become his lover if he will teach her. He agrees to take her as a student.
They soon discover that Maelen’s nascent magical ability has taken an explosive turn, and that she is experiencing episodes of uncontrollable fire. Worse, Maelen exhibits berserker-like tendencies when confronted with danger. If she cannot bring herself under control, she cannot gain the vengeance and justice she seeks, nor can she bring the war to an end.