Kissed by Fire by Michelle Fox

Sometimes when you break a curse, you open old wounds.

Caught up in the supernatural slave trade, mermaid Mila needs saving, not promises of undying love from a cursed dragon. But allies are scarce, making the cursed dragons of Scotland her only hope.

When Niall MacTeine boarded the slaver boat with his dragon brothers, he knew they were going to save people, he just never expected to be rescued himself. Thrown overboard, Mila gives him the ‘kiss of the sea’ and that’s when he knows, she’s the key to his freedom.
But breaking the curse that locks him in his human form requires trust and an open heart. Neither of which Mila gives lightly. Niall will have to prove he’s worth the risk in order to claim his fated maiden.