Butch is a middle aged ex-homicide detective who inadvertently hooks up with the Brotherhood. The thought of a human hanging out with, and living with the Black Dagger Brotherhood is unheard of. Most vampires who aren't in the Brotherhood don't even do that. But, Butch is different. He feels like he belongs, and his Brothers feel the same way.
Butch falls for Marissa, the vampire who Wrath used to feed from, but she doesn't seem to return his feelings. When Butch is taken by the Lessers, tortured, and is given a piece of the Omega's evil, no one knows if he'll survive. After Vishous finds him, he is taken to Marissa's brother, Havers - a vampire doctor. As soon as Marissa realizes Butch is there and is in really bad shape, she finds his room and stays with him till he heals.
During his stay at Havers', it is revealed that Marissa didn't even know Butch had come to see her before, and they confess their love for each other. Havers is appalled that his sister, a member of the vampire aristocracy, would fall for a human, and kicks her out of his home - an hour before sunrise (and we all know what sunlight does to vampires). Not knowing where else to go, she ends up at the Brotherhood's mansion.