His Realm by Mary Calmes

On their first meeting, Varic Maedoc, prince of the vampyrs, told Jason Thorpe that loving him was not for the faint of heart. He wasn’t kidding. In the past two years, Jason has been kidnapped, lived through several attempts on his life, and foiled a coup. Now, his new life as the prince’s consort and adviser to the king is made even harder by Varic’s prolonged absence. With his prince off hunting down a traitor, Jason must fend for himself.
While the separation doesn’t last, even Varic’s return won’t stave off the wicked plotting of others, and Jason soon finds himself—again—fighting for his life while navigating ancient betrayals and revenge put in motion before he was even born. And he must prevail because his prince needs him to bring a place without honor back into his realm.
But what festers in rage and bitterness is something Jason never expected, and nothing he’s experienced in his human life, or in the decadent court of the king, could’ve prepared him for the wrath that’s about to be unleashed.

Varic needs both his crown and his consort to be the king he’s always wanted to be, and it’s up to Jason to make sure their bond never breaks.