Tarnish never talks about her past, and nobody is brave enough to pry. However, she arrived at the clan as a lonely, scared hatchling and either did not know or would not say where her parents were. Most assume that she was abandoned, as any mention of her parents sends her into a cold rage which often takes days to abate.
As a hatchling, she would ignore what anybody told her to do, and often grew aggressive if they pushed her too much. This behaviour worsened through her adolescence, and she began taking long trips away from the clan from which nobody was sure if she would ever return. However, she always did, often accompanied by shady characters from other clans or with a heap of trinkets which she would pawn off at low prices. Suspicion grew as to her activities, but Tarnish was shrewd enough to make sure there was no hard evidence of any... unsavoury activities.
Her aggressiveness mellowed out as she reached adulthood, and she began offering help to others in the clan. Any work would do, whether it was manual labour or bookkeeping. For some time, the clan believed she had turned over a new leaf, however it quickly became clear that this was not the case. Although Tarnish never asked for money from those she helped, she made it clear that she expected compensation. A favour here and there, locating certain items, bringing in certain dragons for a "chat" with her...
Nowadays, the only dragons that accept Tarnish's help are the desperate and the unaware. She accepts both, with a smile on her face.
Sly and perceptive, Tarnish appears to be friendly and helpful to the few clan members who have not met her before or heard about her fearsome reputation. She will often offer to help other dragons out with various issues they may have, especially if those problems involve money.