Best Friend's Blood (Ironwrought #3)
Anna Wineheart

Leo has loved Mitch since middle school. He hates the vampires for killing his parents, and hunts the vampires with Mitch, needing his revenge. Except a night out ends up with Mitch turning--he becomes Leo's worst nightmare.
Despite his reservations, Mitch wants Leo's blood. He wants Leo closer, wants Leo in his bed. And despite Mitch's new vampirism, Leo can't shed his love for his best friend. He loves Mitch with no clothes on, loves the touch of Mitch's lips on his neck. Mitch has become the very creature that murdered his parents... but Leo can't stay away.