Swallowtail Dragons are graceful and quick flyers, much like their namesake bird. They are capable of precise aerial acrobatics, and can reach very high altitudes. Because of this, humans observing these dragons are often astonished at how large they are when confronted up close. A Swallowtail’s diet consists of insects and small mammals plentiful in temperate forests. These dragons are also made remarkable by their paper-thin wing membranes, which allow light to pass through, creating an astonishing effect on starry nights.

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.

Seven of Nine is convinced of several facts: she is female, she is not really a dragon but an ancient fay-creature trapped in a dragon's body, and she will get her freedom back once she has grown old and wise enough to grow nine tails. While she waits for this to happen, she passes the time by playing tricks on the humans or playing games of cunning manipulation with the Bloodscales.