Great, she'll have a lot of interesting happenings to deal with there. Let's get to describing her in great, vivid detail. A good character also deals with conflict, so what's hers? You've got two ideas kicking about.
Born in the Vale of Arryn as an identical twin, she spent most of her days as a fishmonger, trying to make enough money to support her ailing father. When fired for a theft she didn't commit, and faced with the impending death of her father, she became what she had never been, and stole from the local magistrate to purchase medicine. Her sister was then mistakenly captured and executed for the crime, just before she could admit to it and explain the mistake. Now, though a successful merchant enjoying the luxuries she was never afforded as a child, she still sees the face of her dead twin sister in every passing reflection
Unlucky in love for all her life, at the age of twenty, she finally finds a man she considers a soul mate. The wedding was as beautiful as it was expensive, and the next day she woke to find nearly everything of value in her possession gone, along with her new husband. Without the ability to trust again, she became a justice of the state, famous for delivering harsher sentences than any of her peers. One day, years later, the man who'd betrayed her appears in her court for the same crime, but done to another woman. She doesn't understand why, but he's the first light sentence he's been able to pass in her career. At the age of sixty, she has finally learned forgiveness.