The Fealty of Monsters - The Fealty Of Monsters, #1

Winter 1917. After years on the run from a dangerous cult, twenty-three-year-old Sasza and his father have established themselves among the Odonic Empire's ruling class. But there's a problem: Sasza is a vampire, and vampires aren't supposed to get involved in human governance. What the aristocracy doesn't know, after all, cannot hurt them. Unfortunately, Sasza is far more involved than a stealth vampire should be.
Not only does he work to quell the rumors of the vampires' responsibility for an unsolved massacre, his lover is also the pro-proletariat Ilya, the Empire's Finance Minister, who tries to recruit Sasza into the same cult hunting him. Then-the Emperor declares war against the Vampire States. Diplomacy has failed. Sasza quickly learns that he will do anything to preserve peace-including giving in to the monstrosity he spent so many years concealing from even himself.