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.

CuSn gets her name from copper (Cu) and tin (Sn), the two metals used in the making of bronze.

Raised in Mistshire Valley, CuSn was once restless for adventure. She once traveled the world, trying not to get captured by humankind. After a few years, however, she was captured by a moderately powerful mage. He spent some time studying her, and discovered a spell to control her physical movements. He transported her far to the northeast of where he caught her, on the edge of the Voiceless Desert. She was then used as a weapon in a fledgeling war against her own kind. In the first battle in which she was used, the mage was slain by a shadow walker that had slipped through the human's defenses, and CuSn was released from the spell.

She joined the dracons who saved her, and let them take her to their city. At first, she was shell-shocked and was nervous of everyone, but eventually found herself at peace in the city, and changed her name to Cubrosna, which she still uses today.