Medalon Book One of the Hythrun Chronicles

According to legend, the last king of the Harshini sired a half-human child, known as the Demon Child, born to destroy a god . . . The Sisterhood of the Blade rules Medalon with an iron fist--an iron fist within the steel gauntlet of the Defenders, elite warriors sworn to uphold the sisters and keep Medalon free of heathen influence. R'shiel, daughter of the First Sister of the Blade, has pulled against the short leash of her mother ever since she was a child. Her half-brother, Tarja, is the dutiful son who serves as a Captain in the Defenders. But when they run afoul of their mother's machinations, they must flee for their lives. They soon find themselves caught up in the rebellion against the Sisterhood, though they revile their fellow conspirators heathen belief in the Harshini--a fabled race of magical beings thought long extinct. But then Tarja & R'shiel encounter Brak, an Harshini outcast, who forces them to face the most shocking fact of all: the Demon Child, thought to be nothing more than legend, may have been loosed in Medalon.