Guardian Dragons have large shields on the end of their tails. Although the shields appear to be heavy, they are light, yet nearly unbreakable. Guardian Dragons use their tail-shields, as well as their wings, to deflect attacks and protect others. Often, they will guard the eggs and hatchlings of a nest while others are away. They are generally peaceful, and will not retaliate unless necessary. They have no need to forage or hunt, as they are fed by those they protect.

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.

Defender, Def for short, was the second of the First Four to hatch and is a calm, level-headed guardian that keeps the peace in the cave. He's not only the guardian of the cave but also for any dragon in need. He excels at battle training and uses his natural talent for the greater good. Dragons everywhere respect his words and what he has to say. Even though he's only a few hours younger than First Punch, he lets her be the dominant one, having no wish to take on that role. Even when he is upset, he keeps his face even and temper under control. Def tries to set a good example for the hatchlings whenever they are near.