When Water Dragons mature, they lose the ability to survive on land, entering the water permanently. They are adept swimmers and eat whatever fish are in the lake they live in. They tend to inhabit the same lake for their entire lives, although a few live in the ocean and swim all over the world.

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.

Tethys is a dragon of the sea. She refuses to live anywhere else. Gyatso the Forlorn can have his little lake, but according to Tethys, the vast open ocean is the only body of water large enough to contain her. Tethys is charged with protecting the coastline of the Ruda Clan's territory. She is called the Silent for her preferred method of attack: overtaking a target by surprise. Except for when she surfaces for air or to speak with clan mates, Tethys spends her time completely underwater, where she has the advantage. She has tussled with invading Water dragons and shown impressive brute strength in the water, but what she is most known for is how she attacks dragons flying above the water, building speed to launch herself from beneath the surface, grabbing an unsuspecting invader in her jaws, and dragging it back down to the water where it is helpless beneath her might.