Killer Queen by K.L. Hiers

Ryan Dew has a very bad habit.

When life at home becomes intolerable, he takes it out on the world. He solicits men and ends their life, and he’s already racked up quite a body count for only twenty-two.
His life changes forever when he picks up Ormenus Wright, a man with money to burn who refuses to respect Ryan’s one and only rule: He doesn’t call anyone Daddy.
Ryan knows how to handle men who won’t toe the line, but there’s only one problem…
Ormenus may not be human.