Each Fever Wyvern carries a unique and very deadly disease on the spines of its tail. To make up for a lack of physical strength, the dragons use this disease to their advantage by poisoning prey and fending off attackers. The illness will quickly render victims helpless before eventually killing them. A Fever will track its prey until the target can no longer move. Usually a solitary breed, these dragons will only come together during mating season, and will flare out the brightly colored sails along their wings to help attract potential mates. Although it has been observed that the wyverns are nocturnal, they will often pick an open spot of sunshine to curl up in and sleep as the day passes by.

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.

Bactrium is often seen gorging herself upon scavenged carcasses, a habit that has led other fever wyverns to sneer and give her the unsavory nickname of Vulture. Yet the cause of her behavior is not laziness or incompetence, as the others imagine, but cunning and foresight; she stalks diseased animals to harvest their bacteria more than her meat, dipping her tail in the blood of those that die particularly swiftly and adding their lethal mixtures of diseases to her own. When times are hard and prey is scarce, the effort pays off--the bacteria flourishing on her tail can down a victim within twenty-four hours, giving the meal little time to wander about and attract the attention of other starving fever wyverns before she can start dining. While she thus usually has ample time to eat all the meat herself, she often leaves a few of the more unsavory bits behind, laughing in contempt as those shameful souls who mocked her finally arrive to scavenge her leftovers.