Originating from a single species that thrived in ancient times, Xenowyrms have become an incredibly diverse breed whose appearances vary depending on their habitats. Each Xenowyrm subspecies is heavily reliant on the power of different types of mana, making them powerful magic users. Aso dwell in the frigid waters of the far north and south, and are occasionally spotted near tundra shores and ice floes. Their isolated homes of choice suit their tendencies towards small family groups or being solitary. Their bodies are so cold they nearly instantly freeze anything they come in contact with, be it water or living creature. Over time, the ice that breaks off their bodies as they move forms into glaciers they use as lairs. The older an Aso is, the larger their frozen abode.

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.

BSG (thought to be an initialism for "blue serpentine giant") doesn't mind friendly interactions with other dragons and humans, but he enjoys alone time. Most of it is spent observing the sun: not directly, but through projections using ice panes and walls. (He may be highly magical, but he's not invincible.) His interest in the sun and its activities began when he was small, when he noticed ice melted faster in the heat of day. As he aged, he developed a general interest and then a curiosity about sunspots. BSG records sunspot observations by carving into a set of underwater slabs that take up far more space than his living quarters. He used to tell other beings about his charts, but he got tired of either being mocked for his time-wasting endeavor or listening to lectures about how a certain shape of sunspot causes mood swings or something. Some dragons still remember what BSG does, but the current generation of humans thinks he's patrolling his territory during sun-viewing time.