Izmael and Evelyn are a Mysterious and Dangerous Sibling Pair with a Hunger for the Blood of People, which Kill for no Reason at all. They were once Prisoners in the UndergroundPrison, Tartarus. More isn't known about them about the Moment.
Izmael is more the Sardistic Type of Guy, who kills his Victims in the Most Brutal way Possible, while Evelyn has more Heart then her Attached Brother. Sure, she kills like a Bloodthirsty-Maniac, but she always Hesitates on a Younger Victim.