Vampire Dragons are members of the undead. They sustain themselves by drinking the blood of others. It is said that they are only “alive” at night, and seem dead or asleep during the day, as they cannot endure sunlight for long periods of time. Vampire Dragons can only reproduce by changing the eggs of other dragons, puncturing the shell with their fangs and injecting venom that kills the baby inside.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Cain is, in a twisted sense, Alucard's son, being the only egg he successfully turned. However, the younger male soon grew bored with only the older dragon for companionship, wanting one his own age to be with. In the dead of night Alucard left the cave to seek out a new playmate for the young dragon, as he couldn't get near the eggs in the cave to turn any. He returned with an egg he had found, likely abandoned by dragons of its cave, from which hatched Celene. She and Cain became fast friends and later fell in love. Cain is the only who can keep this fierce female tamed so she doesn't bite the eggs, jealous of the other dragons who can offspring, something they both desire but cannot have.

The only other dragons that tolerate their presence are the pair of female Marrow Dragons, who, like the Vampires, cannot have young of their own species.