Catch the Lightning — Catherine Asaro

In the distant future, the Skolian Empire rules one third of the human galaxy, and is the most powerful of all. For the ruling family has the power of telepathy, and through it, the ability to communicate faster than light... across interstellar space. But their most determined enemy, the traders, who thrive on human pain, need to interbreed with a Skolian to gain their powers. And now they have her.