Waterhorse Dragons received their name due to their horse-like physique and endearing behavior. They are capable of surviving out of water, and when on land their skin secretes a gelatinous goo to retain moisture. However, their large paddle feet are better suited for swimming, and waterhorse dragons tend to move very awkwardly when on land. Waterhorses are very friendly dragons and enjoy playing with humans.

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.

From inside her egg, Patronus could hear the other dragons in the cave playing and was eager to befriend them from the day of her hatching. She tried to encourage them to play in the deep pool at the end of the cave, though she learned quickly that they weren't all as fond of water as she was. Eventually she grew into a fully formed dragon, and spends much of her days diving into the pool and playfully splashing any who come close enough.