Impostor (Children of Lorcan #2) by JM Rose:
 
NIKOLAI PETROV HATES LIES.

Finding out he’s supposed to be the next Vampire King of Raspien was not something Nikolai Petrov ever expected. Torn from his family and his home, Nikolai is thrust into an unfamiliar world with unfamiliar people.

But it does not feel like the court of vipers he was warned about. Nikolai is surprised by the warmth of his new family and Lord Councilman Caius Varga, immersed in his new school and his new friends, and somewhere along the line, he stops counting down the days until his return home.

His willingness to stay and take up his promised role only grows when he meets the enchanting Lord in Waiting of Amenti, Viktor Kamel. Swept up in romance, friendship and the prospect of learning under the Petrov Academy’s best healers, Nikolai finds himself more deeply entangled than ever in his role as a prince of Raspien.

But things aren’t always what they seem. Nikolai’s warmth, kindness and honesty cannot protect him from lies told in decades past; in the end, the truth always comes knocking and the shadows of the past have teeth as deadly as the ugliest of secrets.