In the Service of the King by Laura Kaye

Kael McQuillan, Warrior King of the Vampires, loathes the Night of the Proffering. He needs the blood of either his mate or a human virgin to maintain his strength, but hasn’t enjoyed the ritual since he lost his wife centuries ago. Kael doesn’t want a new companion, yet his resolve is tested when he meets his newest offering. She’s beautiful and poised, but her curious, mismatched eyes intrigue him more than they should, and when he hurts her, he can’t help wanting another chance…

Shayla McKinnon knows the rules: Serve the needs of the Vampire Warrior King. Obey his commands. Don’t ask questions. But knowing the rules doesn’t always mean that Shayla follows them. She’s waited her whole life for this moment, for a chance to become part of another world—for the possibility of getting justice for those she’s lost. And Kael is her darkest fantasy come to life, even though he’s intimidating as hell, too.

Now they’re locked in a red-hot battle of wills, and the only question is which one will end up on their knees…