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.

Mint colored dragons are the most peaceful of all dragons; they only eat plants unless they scavenge meat from an already dead animal. They also have no ways to attack others or defend themselves. They are much smaller than other forms of dragons since they only double in size when they mature. Mint dragons are unable to use magic and cannot fly since they lack wings. Their looks have given rise to the common insult of calling dragons "large lizards."

Kei-kun, full name Keitaro, is often teased by his peers for his lack of remarkable abilities. Still, he made his way into many of their hearts, even if he can become pretty nervous in a bad situation. When the others are fighting over something petty, he's the one huddled in the corner with Tina Sparkle and any other timid ones, hoping he's not dragged in somehow. This works about half the time, as he makes good leverage. Even A-chana has shown she's willing to push him into something he doesn't like. The whole group likes Kei-kun for his sweet nature. Even the males have shown some kindness to him, after they made Youssarian so socially awkward. Still, some end up going a bit too far, using him as a way to get what they want or playing too roughly with him.