Those who hunt.
The Black Blooded Children of Kaius
700 years ago the hunter king Kaius wandered amongst mortal demihuman kind as a protector of the world. He served this role up until his noble sacrifice in an effort to stop a plague that was corrupting every living creature of the world. He left behind 800 followers he referred to as his children to serve as guardians against the lingering horrors of the world.
The Black Blood order was formed and has served as wandering mercenaries mainly tasked to hunt creatures that threaten the rest of mortal kind. The opinion of the order depends on who you ask. They are the saviors and avengers to the farmers and peasants and seen as a possible threat by some powers that be. Many fear the unusual powers posessed by their kind and and some are unnerved by the striking darkness in their physiology.