Black Dragons are warriors. They are strong and capable in battles of force, but also ample magic users, capable of devastating opponents with their spells. Their bright eyes give them excellent night vision, which is why they generally hunt during the night.

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.

Karl enjoys fighting, and will often spar with the other dragons, provided they agree to. Despite his combative and aggressive nature, he rarely bickers with the other dragons, and is usually very calm and level-headed, almost never losing his cool. In fact, sometimes he can be too cool towards the other dragons, something that leads to conflict with Thomas, who gets rather miffed when Karl doesn't reply to her.  (Karl named Thomas. He just liked the name and decided it suited her.)

He is very affectionate toward Thomas, who he sees almost as a little sister (or possibly something more, though he'll never admit it of his own free will), and spends a fair bit of time with her. He pretends to ignore Thomas' advances, and even discourages them, in spite of his own interest in her. He appears to be wavering, as of late.