Hellhorse Dragons are foul-tempered, spirited creatures with tempestuous and violent dispositions. Torrents of scorching flames erupt from their bodies and can easily set their surroundings ablaze. Highly aggressive and territorial toward other dragon species, Hellhorses will tolerate others as long as they believe the association to be beneficial. Such alliances are tenuous in nature and frequently short-lived, as the slightest disagreement can easily escalate into a full-out brawl.

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.

As soon as she discovered there was a zoo not far from her homeland and learned what it was, Horse of Hades began storming it at night, running through the park and wreaking havoc on the pens, not more than once or twice a year because that is an energy-draining activity. She's never destroyed a pen's walls; she just damages them a little and leaves, so perhaps the dragons inside can finish the job if they want. Nicknamed Satan's Steed, Night Mare, and the Two-Toed Terror, among other things by the humans, Horse of Hades is able to get away with what she does largely because they attribute her runs to typical Hellhorse temperament and don't realize these are all planned. Nobody but her close friends—and she has none—knows whether she invades the zoo because she cares about the inhabitants, or because, pens or not, there are dragons near (and near is close enough) her territory.