In the Galactic Roman Empire, eight noble houses fight for power. One gladiator fights for justice. This is "Wolf's Empire: Gladiator," by Claudia Christian and Morgan Grant Buchanan.
When her mother and brother are murdered, young noblewoman Accala Viridius cries out for vengeance. But the empire is being torn apart by a galactic civil war, and her demands fall on deaf ears. Undeterred, Accala sacrifices privilege and status to train as a common gladiator. Mastering the one weapon available to her a razor-sharp discus that always returns when thrown--she enters the deadly imperial games, the only arena where she can face her enemies.
But Fortune's wheel grants Accala no favors the emperor decrees that the games will be used to settle the civil war, the indigenous lifeforms of the arena-world are staging a violent revolt, and Accala finds herself drugged, cast into slavery and forced to fight on the side of the men she set out to kill.
Set in a future Rome that never fell, but instead expanded to become a galaxy-spanning empire, Accala's struggle to survive and exact her revenge will take her on a dark journey that will cost her more than she ever imagined."