Blacktip Dragons are a small, shore-dwelling breed that tend to nest on sheer ocean side cliffs. They live in groups under a dominant female, who prevents her subordinates from breeding. During the mating season, a group of Blacktips can be very noisy and smelly indeed; males produce a distinctive musky odor and loud, low-pitched honking noises in an attempt to woo the alpha female.

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.

Donna is a loud, proud, no-nonsense female. As dominant Blacktip of the cave, she rules over and controls much of the goings on, though her control is only absolute when it comes to the others of her species. Though tough and aggressive, Donna is incredibly gentle and loving when it comes to her son, the Metacrisis. There's also very little she wouldn't do for her mate, the Tenth Doctor—except let him, as she sees it, 'shirk his duty' to go out traveling with the other doctors and their friends. She doesn't seem to fully understand her mate's private discomfort with his role, and that he wants above all else to be freer with expressing his wants and needs.