Of Blood and Angels — J. Naomi Ay

In Book 3 of the series The Two Moons of Rehnor, Senya and Katie have settled into a somewhat normal life. It does not last long though as Senya is plagued by a strange and debilitating blood condition brought on by the task he has been sent to Rozari to complete. In a moment of weakness, he is captured by his nemesis and uncle, Prince Akan. Commander Katie and the crew of the Starship Discovery fight to save him, eliminating Akan as a threat, and leaving Senya's path to the throne clear. Now Katie must learn to live within the restricted rules of the Rehnorian Court or escape back to the stars for her last chance of freedom. There is other evil in the galaxy though and for their own safety, neither Senya nor Katie may have a choice.