Shadow Wizard by Jeffe Kennedy

Spy, manipulator, traitor… He might be her only salvation.

Lady Seliah Phel can’t escape feeling like she’s one of those fairytale princesses awakened from a long slumber—except that her life is no romantic story and there’s no happy ending in sight. Though she has her magic and she’s been rescued from the depths of madness that consumed her since adolescence, Selly finds that the years she lost aren’t so easily recovered. Everyone treats her like the child they remember. To prove something—perhaps only to herself—she’s recklessly volunteered to stave off a host of monsters with only the enigmatically alluring, cuttingly sarcastic, and probably deceitful wizard Jadren El-Adrel for company.
Jadren isn’t the heroic type. In fact, he’s not much of anything. Relentlessly groomed into a shadow of a man by his sadistic mother, he’s the perfect spy and tool, with no real will of his own. When he’s stranded in the wilderness with Seliah Phel, he figures the outcome is immaterial. Live or die, it’s all the same to him. But Seliah is a different story and she isn’t like anyone else. Though he reminds himself she’s basically a child in a woman’s body, he finds it increasingly difficult to resist her artless charms and relentless curiosity.
As their predicament goes from dire to disastrous, Jadren realizes his many failures have jeopardized Selly’s future, perhaps her very life. Far from home and trapped without resources, Selly has only Jadren to rely upon—the one person she can’t possibly trust. There seems no possibility of rescue from their friends and family back home at House Phel, so Jadren and Selly must work together to survive… if they can.