From the back cover:

BROTHERS OF EARTH

The leader of the Hanan was a Priestess-Ruler in a world of humanoid aliens. Yet she was more closely related to her human prisoner, Kurt Morgan, thought their star nations had been bitter enemies for two thousand years. She granted Kurt Morgan his life, but for a price: that he remain indebted to his captors, immersed in an alien environment which threatened to drive him mad. Beset with doubts, Kurt accepted the terms of his capture and despite his misgivings became intrigued with his life. For he shared something unique with his captor -- both of them had survived the destruction of their worlds. And then they realized that the world on which they now lived was on the brink of a devastating war, and they were perhaps the only two sentient beings there who understood the ultimate sacrifice that might come from such a conflict. Could they save this world, or would they die with their adopted planet, humanity's orphans at the edge of space?

HUNTER OF WORLDS

The Iduve were the most advanced spacefaring race in the galaxy. They traveled where they pleased in giant city-sized vessels, engrossed with their own affairs. The Iduve were humanoid, but they differed from Earth's own humans in one significant way: they were pure predators incapable of human emotion.

Aiela was a world-survey officer who found himself abducted to serve the Iduve clanship Ashanome. Forcibly mind-linked with two other captives, life for Aiela became wholly dedicated to the service of his captors.

But then the Ashanome came to the world of Priamos, a war-torn planet caught in a struggle between humans and the alien race known as the amaut. When she discovered that her fugitive brother was hiding there, Chimele, leader of the Ashanome, was willing to sacrifice this entire world to destroy him. And Priamos' only hope for survival lay with Aiela and his fellow captives....