Claire Eliza Bartlett The Winter Duke

She survived the curse. Now she must survive the throne. All Ekata wants is to stay alive--and the chance to prove herself as a scholar. Once Ekata's brother is finally named heir to the dukedom of Kylma Above, there will be nothing to keep her at home with her murderous family. Not her books or her experiments, not her family's icy castle atop a frozen lake, not even the tantalizingly close Kylma Below, a mesmerizing underwater kingdom that provides her family with magic. But just as escape is within reach, her parents and twelve siblings fall under a strange sleeping sickness, and no one can find a cure. In the space of a single night, Ekata inherits the title of duke, her brother's captivating warrior bride, and ever-encroaching challengers from without--and within--her ministry. Nothing has prepared Ekata for diplomacy, for war, for love...or for a crown she has never wanted. If Kylma Above is to survive, Ekata must seize her family's magic and power. And if Ekata is to survive, she must quickly decide how she will wield them both.