Divided Fire — Jennifer San Filippo

In a rich fantasy world where Songs literally move heaven and earth, one sister must use magic and the other must rely on strength to reunite when pirates, greed, and war tear them away from each other.

Miren has never allowed jealousy of her sister's magic keep her from taking care of Kesia, and Kesia has always depended on her big sister. When Kesia is kidnapped, Miren will do anything to get her back -- even team up with her sister's aristocratic and seemingly ineffectual boyfriend. Neither sister had ever left their small fishing village before, and now they are plunged into the wider world, minor players in a war between nations. Each sister faces external and internal perils, and each finds surprising allies and unexpected strengths. How will the two find each other again? And what will become of them if they don't succeed?