Undine Dragons are named for the water spirits with which they share territory. They have close relationships with these spirits, and are able to communicate with them. In exchange for protection and respect of their mutual freshwater homes, laid eggs are often protected by a blessing. This blessing stays with the dragon into adulthood, and with it they gain potent magical abilities. Sometimes when an Undine Dragon becomes very upset, the ground at their feet may frost over or begin to steam. They have also been observed to manipulate water directly, rerouting raindrops or creating puddles from groundwater. Undine Dragons always live near forest pools, streams, or waterfalls. Both genders take equal part in the raising of young and are very good parents—though they may not remain mated after the offspring are grown.

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.

Suijin Green, brother of Seishin Lake, is the more reserved of the two. They were stolen together and raised together, but Suijin often wonders what their life would have been like had they remained in the mountains with their birth parents, whereas Seishin is happy where he is. He is more proficient with his powers than his brother, which he believes is due to his calmer demeanor and ability to hone in on things, unlike his easily excited brother. As time passed he had a child with his "niece", but then found a lifelong mate in Mori Kodomo. He is quite content in his life, especially since his mate gets along with his child Kinko Dreams from his first mate.