The Highlord's Daughter, Book 3, Highlord of Darkness Series — Christine W. Murphy

The Highlord of Darkness finally has his male heir, and a daughter, but if Narragan has anything to say about it, neither of them will follow in his footsteps. With the galaxy no longer at war and Orgon on the road to full membership in the Triden Empire, Narragan is working to end the traditions that require the Highlord to be the Evil One. But forces off and on the planet are plotting to bring an end to Narragan's reign, and both he and his son are targeted. Narragan may want to believe that his teenage daughter is still just his little girl, but Ally has hidden strengths. Are they enough to save Orgon and her father's sanity?