Desires of the Night by Taylor Dawn

Gia Pendleton wanted one thing—to find her missing brother. The last clue she followed led her to Las Vegas’ Club Desire, a place for vampires to act out their kinky fantasies. Upon meeting Layton Kyle, the owner of the club, Gia quickly realized her preconceived notions of the undead didn’t match reality.
Layton Kyle has walked the earth for over a century but finds himself second guessing his decision to become a child of the night. The mundane existence he lived became upended when a curvy blonde human barged into his office, searching for her missing sibling. His instant infatuation leads him to strike a deal with Gia—he will help locate her brother in exchange for her becoming his play toy.
With the contract signed in blood, Gia and Layton embark on a relationship that could be their undoing.