Dark Lover ~ J. R. Ward

This is the first book in the Black Dagger Brotherhood series. Beth is a reporter in a small town in New York, Wrath is the leader of the group of men who are charged with protecting the small group of vampires who live in the area. The time approaches when Beth will go through the transition, and her father, whom she has never met, asks Wrath to see her through it, shortly before he is murdered. Though Wrath had refused, now that her father is dead, he feels he needs to do this favor for him now.