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.

When water dragons mature, they lose their legs and the ability to survive on land, entering the water permanently. They are adept swimmers and eat whatever fish are in the lake they live in. They tend to inhabit the same lake for their entire lives, although a few live in the ocean and swim all over the world.

Unagi-sama is the ruler of the chain of lakes which dot the river that runs near the cave.  He spends his days in the largest lake upriver with his mate, Namioto, and their children, Liberi and Nalli.  The local fishermen have dubbed that lake Wyrmwater, and always dump a part of their catch back into the lake as homage to the great serpents who share the waters with them.  Unagi-sama, for his part, has been known to lend aid to the fishermen when disaster strikes, such as a deckhand being washed overboard.  In fact, it was the humans who started referring to him with the "-sama" honorific, until it eventually became part of his name among the other dragons.