Deep Sea Dragons, as their name suggests, spend most of their time in the darkest depths of the sea. They have a bioluminescent dorsal spine that serves to attract prey and communicate with their own kind. As with many deep sea animals, they generally eat whatever they can manage to bait. They rarely leave the ocean floor, surfacing only during breeding season. When they do choose to travel to the shallower depths, they avoid bright lights and will only come up far away from shore.

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.

Missun is often referred to as "the Mystery lady", because she spends most of her time in the darkest depths of the ocean and surfaces very rarely, even by deep sea dragons' standards. She is reclusive and hasn't spoken to other dragons for years.

However, during a discussion with "Hellodaydream", she has revealed outstanding intellect and amazing wisdom. She later confessed that she doesn't talk too much because the creatures on the surface aren't ready to receive knowledge of the Abyssal world she lives in yet, as it is alien-like, very different from the standards of the rest of the planet.

The sorceress and Missun seem to have exchanged information and confidences, and it is rumored that this dragon is among the few to know her mistress' true name.