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.

Indeed, this dragon shares the name 'Lei' as certain female dragon, but the 'Last' in his name contain not the agony of being abandoned or so.

Instead, 'Lei Soeir' means 'Last Wish'. Coming from a long line of pure-bred Hellfires, whose reputation of being fierce has been very-well known amongst Dragonsages, this egg is bestowed upon the tame female Hellfire to be taken of. The only wish of the old Dragonsage that asked Lei Umine to take care of this egg is simply to 'raise the hatchling to be a Hellfire unlike others'

And so, the dragon Lei Soeir is born and raised. Unlike other vicious, petty, antisocial, and passive-aggressive males in his breed, this dragon inherited his foster mother's traits. Even after maturing, he still stick around Umine, while acting childish. It has made some foreign Dragonsages gape in shock upon seeing that attitude.