Balloon Dragons are so named because they are filled with a gas that makes them almost lighter than air, similar to balloons. However, they are not prone to bursting, as they are covered in tough skin and can deflate themselves if necessary. In addition, they generally are slow moving. They use their gas bladders to float to the tops of trees, where food is more abundant. They can shift their weight from their backs to their fronts, allowing them to reach leaves and fruit.

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.

Jupiter is a little grumpy and doesn't like to socialize with the other dragons; he'd much rather float to the tops of trees and eat fruits that he finds. He is a loner by nature and will usually not tolerate anyone but his tamer and a few other dragons to come near him. When he feels threatened, he may blow up to twice his normal size and hiss until the offender leaves.