Hellfire Wyverns are so named for their foul tempers and fiery visages. Their social structure places all females above all males, due to superior physical characteristics and violent dispositions. Forced subservience of the males causes them to become vicious, petty, antisocial, and passive-aggressive compared to the aggressive and social females. However, orphaned hatchlings raised by foster parents of another species can develop surprisingly even tempers and mellow dispositions, proving that their defining unpleasant nature is, in fact, a learned behavior.

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.

One of the clan's first members, Thermosa has appointed herself as the Clan's cook. Whenever food is brought in it's delivered straight to her cavern where she and a few other Hellfire Wyverns clean the food before roasting it with their flames. She's got a bad temper and can be very bossy, but she doesn't do this to be mean, she's a very passionate dragon who cares deeply for her clan. She has a soft spot for the hatchlings and is known for saving them some of the tastier treats.

Her good mood vanishes whenever Sub-Zero returns from a hunt. That means she's got to put in a LOT of effort to defrost the frozen catch before it spoils. She's complained to the council and to King Cerulean, but they keep reminding her how helpful Zero is, because whenever he brings back a catch it's often very large prey.