Invader

From back cover Daw paperback February 1996:

SECOND CONTACT

Nearly two centuries after the starship Phoenix disappeared into the heavens, leaving an isolated colony of humans on the world of the atevi, it unexpectedly returns to orbit overhead, threatening the stability of both atevi and human governments.

With the situation fast becoming critical, Bren Cameron, the brilliant, young paidhi to the court of the atevi is recalled from Mospheira where he has just undergone surgery. But his sudden and premature return to the mainland is cause for more then mere physical discomfort. For during his brief absence, his government has sent in his paidhi-successor, Deanna Hanks -- representative of a dangerous archconservative faction on Mospheira who hate the atevi. And though she should despair when Bren is once again able to fill his post, no recall order comes.

Cut off from his government and haunted by the continuing threat of assassination, Bren realizes his only hope may be to communicate directly with the Phoenix as the spokesman of the atevi -- an action which may cut him off for good from his own species.

Synopsis from Open Library.