The Guardians of the blood are human in appearance but with unnaturally pale skin. They are where the blood in vampire mountain comes from. They also are in charge of the preparations of the cremations of dead vampires.In return for their services, the guardians of the blood receive the organs of the dead vampires, which they eat for special occasions. They rarely speak and never interfere with events except in indirect ways. This is mentioned to be part of their beliefs.
In book 11, The Lake of souls, there are people who resemble the gaurdians of the blood. It is theorised that the guardians of the blood may have been brought back from that future time to the past making them the descendants of mutated humans.