Frilled Dragons are smaller than most other breeds, but when threatened, they stretch out their wings and frills to appear larger. They generally do not like to fight and prefer hiding to confrontation. Frilled dragons live in small groups and often band together to scare off potential threats. Males also use their frills as a way to attract mates, with those displaying the “best” frills being more likely to breed.

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.

Frilled Lucy is Hatori's mate and his assistant. When Hatori is busy in surgery it is her job to keep the patient comfortable and to lend a hand when needed. She is very loyal to her family and will attempt to defend them should the need arise, even though her diminutive size puts her at a disadvantage.<br/>Even though the majority of the eggs and hatchlings in the family are kept in the cave nursery, where they are constantly warmed by Starmakers's magic and are under Yamagishi's watchful eyes, Lucy prefers to take care of her own eggs and offspring herself, not letting them out of her nest until they have grown wings.