No Shelter But the Stars by Virginia Black

Virginia Black's No Shelter But The Stars is the space opera you've been waiting for--packed with warring worlds, romantic adventure, and larger-than-life characters. Kyran Loyal is the last heir to the lost throne of a forgotten planet, the figurehead of a nomadic people fleeing the galactic tyranny of a brutal regime. Davia Sifane is the unrecognized daughter of an imperial despot. When happenstance pits them against each other in battle, neither expects the outcome: they are the only two people to survive. Marooned on a barren moon, their only hope of survival is to rely on each other, but what they learn will either kill them or change the galaxy forever.