Brimstone Dragons live in dry arid areas such as deserts where they feed mainly on sheep, goats and the occasional camel. Their favorite habitat is ideally situated close to the wastelands around active volcanoes. This is due to an important part of their diet—sulfur, which they obtain from deposits near volcanic gas vents. Instead of fire, these dragons use the sulfur they ingest to create a noxious gas which they store in their large throat pouches. When in danger, this gas is released in a large cloud. They also eat other mineral rich substances—including charcoal—and will drink the mineral rich (but slightly acidic) water commonly found in deserts and volcanic regions.

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.

When a boulder, a tree, or an attacking dragon needs moving or removing from Damian's oasis, Harun is the first pick for the job. He is a veritable wall of muscle and scales, and his sulfurous breath is more than enough to deter assailants. Though not stupid, per se, he is simple minded, sorting people, dragons, and objects into two categories: "I like" and "I no like". At the top of his "like" list is a large boulder near the center of the oasis that acts as an excellent sunbathing spot, for solely his use. Attempts to get between the dragon and his boulder will always end violently.