"The Vrykolakas Deviation" [The Narcissus Legacy, Book 1] by Sherri Lackey
They were no more brothers to each other than a cat and a horse are of the same species. But they do have a colorful history which they share, and it isn't a pretty one. When I say colorful, think red, blood red like the Valentine's Day decorated store I mentioned earlier – blood red, but don't think of love in connection to that color.
They hated each other. ~ within Chapter 1