Fated for the Firedrake by Sirena Knighton

A desperate dragon shifter. A witch in hiding. And the attraction that burns between them.

Seranni Vasalt is a witch in hiding. If her powers are revealed, she’ll be forcibly enlisted into the king’s army. After years of hiding, she finally gets the chance to flee to another country, where she plans to use her magic to make money—enough to keep her family whole. So when Seranni sneaks into the abandoned mage’s tower on the outskirts of her town, she’s looking for anything that can hone her powers.

What she finds is a man in hiding. A wild man with coal-black eyes, claws on his hands, and secrets of his own.
A prisoner of war twisted by black magic, Kael has been trapped in an enemy land for almost two years. Desperate to go home, he’s been hiding in the tower as he struggles to reverse the spells placed on him, but with no magic of his own, he can’t decipher the mage’s books. Just when Kael is about to lose hope, he meets Seranni.
Soon, they come to a deal: Kael will give Seranni access to the tower, and she will help him decode the mage’s books. But when Seranni is forced to flee her town and stay with Kael, they find that the attraction between them is stronger than the secrets that keep them apart.
But the runaway mage isn’t done with Kael yet. He contacts Seranni in secret, promising her all of his knowledge in return for turning in Kael, his wayward experiment. Now, Seranni has to make a choice: does she betray the enemy soldier who has hidden so much from her? Or does she trust the gentle man with burning eyes and a scarred heart she could come to love?