Matter of Profit by Hilari Bell

Strangers in a bizarre land—that's what Ahvren's people, the Vivtare, are. They are the conquerors, the rulers now, of the T'Chin confederacy. But Ahvren is no longer sure what that means. After spending two years fighting a brutal war on another planet, here—where not a single shot was fired—victory doesn't seem quite so...victorious. Rumors abound of a plot to assassinate the Vivitare emperor. Sick of the horrors of conquering beings on other planets, Ahvrem wants to find another path. will end his service as a soldier and save his sister from an unhappy marriage if he can discover who is behind a rumored plot to assassinate the Emperor.

So Ahvren makes a deal with his father, if he can discover the plot to assassinate the emperor it will save his sister from an unhappy marriage. He can also choose his own path for the next year, otherwise he will be sent to conquer other worlds. When he discovers that even the rumors are not what they seem he is too late to change fate of others so can only do that for himself.

An interesting, powerful YA novel featuring a variety of aliens. Very well done and thought provocing. Can't wait to read more of her works.