Warprize by Elizabeth Vaughan

The daughter of a Warrior King, Lara was trained as a healer. With her father dead and her incompetent half-brother on the throne, the kingdom is in danger of falling to warring Firelanders. Unable to depose her sibling or negotiate peace, Lara serves her people by healing the warriors—on both sides of the conflict—who are injured in battle.

Lara finds herself educated in her enemy’s language and customs in return for her attention and compassion. She never expects that her deeds, done in good faith, would lead to the handsome and mysterious Firelander Warlord demanding her in exchange for a cease-fire. To save her land and her people, Lara trades her freedom to become the Warprize.