Ice Dragons are fierce predators who hunt using their extremely cold breath. The breath of an ice dragon can freeze its prey solid in seconds. The body of an ice dragon is so cold that icicles will form along its skin no matter the outside temperature.

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.

Ever since he was an egg, the female nest sitters had kept him separate from the others because he was so cold that the other eggs couldn't stay warm. While growing up very few would go near him. The only ones who would approach him were those who could withstand the cold, such as winter holiday dragons and the mountain dragons from the far north.

Zero's mentor, Santa Cheer, had taught him how to harness his power and control it. Zero still stays away from the nests, but the others no longer have to worry about his uncontrolled power. He often flies off to the north to hunt prey and bring it back, through the Hellfire Wyverns have their work cut out for them trying to defrost the food. Thermosa has constantly complained about Zero's methods of hunting, but the ice dragon simply ignores her nagging because he knows that he is providing for his clan.