Shadow Walkers are a strange breed that possess the ability to slip between the planes of reality, becoming immaterial. This allows them to hide in the shadows, either hunting from the concealment of near invisibility or evading enemies. Though they become corporeal to mate or to eat, they spend most of the rest of their lives walking in the shadows. Shadow Walkers are wary creatures, though on dark autumn evenings when the leaves fall to swirl in the chill, rain damp air, they may be seen drifting out from the shadows.

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.

Sivilian and Calunia are two Shadow Walker Dragons and the first pair of that species under Atomix's care. They were raised separately, and became close mates and guardians of her specialized cave to raise abandoned hatchlings, the Cave of the Lost Dragons. They behave like nighttime scouts, and share everything together despite being what many assume is a typically isolated breed. They share meals, hunts, hatchlings and are never "seen" separate. Atomix jokes that if they could, they would share the same body and name, and Atomix lists them under the same description as per her husband's joking request.