Terrae Dragons are primarily herbivores who prefer to eat from the tops of trees. However, due to their massive size, they must rely on small, specialized scales to absorb and convert energy from the sun. Since they live in tightly-knit groups, this form of energy absorption helps preserve the forests in which these dragons reside.

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.

Treesus lives among a herd but will sometimes leave the group for a few hours for some alone time. Largely—in both senses—a pacifist, he doesn't bother fighting unfriendly creatures, relying on size and thick skin for protection. The one exception is when he sees his home undergo large-scale deforestation. He is usually able to deter the humans by towering over them and glaring calmly; however, those who didn't get the hint have observed that the traits that protect the dragon from harm make him a relentless green terror, and that those antlers aren't only for attracting mates.