Cavern Lurker Dragons are nocturnal ambush predators. Although small, they are very aggressive and will attack anything weak enough to be overpowered. Their preferred method of hunting is to lie in wait in a cave, burrow, or other small, enclosed space; when any potential prey passes they will lunge out to grab hold of the unsuspecting victim and drag it back into the lair. Cavern Lurkers have an odd aversion to sunlight and almost never venture out during the day. More commonly sighted are the odd piles of bones they stack near the entrance to their dens. Their mating call is a low-pitched bumping noise.

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.

Dio is one of the most disagreeable dragons in the clan and the source of a lot of trouble. Selfish and greedy he thinks nothing of stealing from or manipulating others to get what he wants. He doesn't care if someone gets hurt because of his machinations and may even put someone in harm's way for fun. Dio constantly fights with K and the two have been known to get into some really nasty scraps.

Whyte, Mamon and Sigma are the only dragons he shows any fear of. Whyte because he could banish him from the clan and the latter two for what they might do to him in a fight, as neither of them would pull any punches.