Despite their great size and strength, Celestial Dragons are a peaceful breed named for their spectral, starry appearance. Little else is known about them, as they spend the vast majority of their lives partially phased out of the plane of existence through the use of powerful magic. Celestial Dragons are thought to assume their corporeal form only long enough to reproduce or to die; the rest of the time, they resemble living, breathing constellations, impervious to all physical and magical harm.

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.

Aratus Ptolemy comes from a family that were particularly proud of being Celestial Dragons. So proud, in fact, that they felt that all other dragon species were inferior to them. In their eyes, simply being a Celestial Dragon made you royalty. Their attitudes even reflected on the fact that everyone in the family was named after a famous astronomer or a particular star formation, and Aratus was no exception. But Aratus did not share his family's deep-rooted superiority, especially after he journeyed down to the terrestrial plane and befriended the Nebula dragon, Comettail Whiskers.