The Empire Trilogy / Daughter of the Empire / Raymond E. Feist, Janny Wurts

Magic and murder engulf the realm of Kelewan. Fierce warlords ignite a bitter blood feud to enslave the empire of Tsuranuanni. While in the opulent Imperial courts, assassins and spy-master plot cunning and devious intrigues against the rightful heir. Now Mara, a young, untested Ruling lady, is called upon to lead her people in a heroic struggle for survival. But first she must rally an army of rebel warriors, form a pact with the alien cho-ja, and marry the son of a hated enemy. Only then can Mara face her most dangerous foe of all–in his own impregnable stronghold.