Thunder Dragons are the masters of electricity. Their wings gather energy as they soar through the clouds, and when they clap their wings together they can create devastating arcs of lightning. They can stay airborne nearly indefinitely, landing only to sleep and breed; they catch their prey from the air and take moisture from the clouds. A thunder dragon’s roar is considered to be an omen of misfortune.

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.

Thunderous Shield was raised with the two Ice Dragon brothers, Vexen and Shadowfrost. He experienced first-hand Vexen's slow descent into insanity and cruelty and know him better than any other dragon in the cave. Knowing that Vexen was a murderer and that he was terrified of lightning, Shield began to guard Vexen's cave to make sure the killer didn't escape to kill as he pleased. He did his job badly, though, not at all stopping hatchlings from entering his cave to then be eaten. Once the Ice dragon Judgement led her army against Vexen, Shield was captured and imprisoned as one of his 'subordinates'. It took some talking and explaining, but Shield was very quickly released after convincing his captors that although he could have done more good, he did no bad. Many dragons have mixed opinions on the ordeal, though Shield tends to simply stick to himself and to his mate, Lovely Wings, intending to forget about the troubles of the cave with her.