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.

Slender is a mute dragoness who lives with a group of Swallowtails. She was one of the first dragons to join, but she didn't accept a mate for a long time. When a male Swallowtail named Monstrous appeared, however, she finally was able to create a family with someone she liked. Why she likes such a weird dragon is beyond the other Swallowtails of the group, but they both are happy to be together.

Slender doesn't like to be in the cave that the group resides in for very long. She usually wanders the surrounding forests and mountains with Monstrous following behind her. Sometimes she comes upon the Swallowtails who were rejected from the group and watches them from a hiding spot. Monstrous likes to have one-sided conversations with her about who the mate-less dragons are and how they act, which Slender seems to like to hear.

The mute female has no problems whatsoever with the guard of the cave, since her heritage is pure like her mates.