Dragons are creatures with nearly unlimited life spans. They can survive for long periods of time, and no one has found a dragon that has died of old age. Adolescence 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. Once they hit adolescence, hatchlings change quickly, maturing to their full forms in only 2 years.

Dragons don’t communicate with each other verbally, but they will growl to scare off predators and frighten prey. Young dragons will emit an extremely high-pitched squeal when they are frightened. To communicate, they use telepathy with each other and to speak to other creatures.

Black dragons are warriors. They are strong and capable in battles of force, but also ample magic users, capable of devastating opponents with their spells. Their bright eyes give them excellent night vision, which is why they generally hunt during the night.

Milennium Earl is a powerful black dragon. Not that he has any special trait, like speed or strength. When he was a hatchling, like the rest of his generation's hatchlings, he was taught how to fly with Suminoe Riko. He fell in love with her during the next months, and eventually became her mate. That is why he is faster than any other dragon, and their love gives him the strength necessary to succeed at any task.