Saga of the Skolian Empire #9: Skyfall by Catherine Asaro

The Birth of an Empire
Skyfall goes back to the very roots of Skolia, showing how a chance meeting on a backwater planet forges a vast interstellar empire. Eldrinson, a provincial ruler on a primitive planet, is plagued by inner demons. But when he meets Roca, a beautiful and mysterious woman from the stars, he whisks her away to his mountain retreat, inadvertently starting a great interstellar war, and birthing the next generation of rulers for the Skolian Empire.