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.

Harold is fat. There is no other way to describe him. He loves really fatty foods, and is particularly fond of beer, which doesn't help. He is lucky that his natural buoyancy enables him to move at all. The younger members of the cave like to bounce on his belly, and for some reason this actually doesn't seem to bother him.

When he was a hatchling, he saw something very alarming at the back of the cave. To this day he doesn't know what it was, and will not talk about it, but he insists on sleeping close to the door, in case it's still there. This is useful for the others when they come in in the dark; if they fall over, they have soft landings. He is jovial in the extreme, and loves to join in a good sing-sing.