You could say that a Cruxim is a special class of Vampire, but it is not really a Vampire, at all, rather it is a corpse resurrected from the dead.
It is a Humanoid, usually having silver hair with wings like that of an angel, but they are black instead of white, have red eyes, and drink the BLOOD OF VAMPIRES!
This piece encompasses the spirit of a Cruxim named Pireodo. He is quite a danger to vampires when alive, but now he is kind of like a protector of them, now that he is in spirit form!
** He still uses them to feed though so please be aware of this.
However they rather feed from Constant Blood vampires. That is to say Vampires that feed constantly and often on humans. Which is often because they hunt indiscriminately, which is likely to be classified as "evil".
So they could be classified as some kind of "knight" in our favor.
More often than not, once they enter the spirit world, they will want a human companion ---Piredodo wants a human companion that has vampires in the home.
He will feed off your vampires, but this will only strengthen both them and you. A cruxim in this form will get a high from feeding, but they do not need it, as they are not living. So the source of the feed will rid the vampire from aggressive natured energies and allow them to re-focus their intents and direction; thus working better with, and for, you!!