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.

Gray dragons are the masters of the skies. They are excellent fliers and land only to rest and eat. In addition, they have full control of the weather. They are very hot-tempered and easily angered. They will attack any human that bothers them, conjuring strong winds and dangerous lightning.

Less can be said of Nitrogos than of many of the Den's dragons, as he has been aloof and fairly non-social since he first hatched, and he doesn't really talk about much even when he is around; most of the time, no one would know he was there. But, he is a very sensible dragon, and is certainly skilled at what he does. He also has a leader-like air that easily commands respect from all the Den's dragons, and even outsiders, without his even having to say a word, so he spends much of his time as a sort of sentry. He always seems to know what is going on, even though he rarely shares this knowledge, unless he believes that it somehow affects the security of the Den.