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.

Sebastian Michaelis is the butler of the Phantomhive household and Ciel's bodyguard, two jobs he is completely devoted to. He often describes himself with the phrase, "Because I'm a butler through and through", which, in Japanese, is a pun. 'Through and through' can interpreted as "demon and", thus his phrase becomes "Because I'm a demon and a butler" something Sebastian is well aware of. He is highly skilled in any area and handles any task, as well as any problem that arises from the errors of the other staff, with ease. This is due to the fact he is a demon bound by a "contract" to abide by Ciel's will. A sign similar to the one marking Ciel's right eye can be found on his left hand, which has been used on one occasion to twist the arm of a kidnapper without touching him. Ironically, he has a soft spot for cats, and has one that he visits during stressful times. His name is similar to that of Father Sebastien Michaelis, who compiled a hierarchy of demons in Hell.