Caterina Blazquez was born in Florida, the daughter of an American mother and a Spanish father. Her father was the captain of a Spanish garrison in St. Augustine. She left Florida at 16 after her mother died. She was very beautiful, described as about 22 or 23, having short golden curls, wide blue eyes, and smooth pale skin, "she glowed like a diamond." (Sharpe's Fury). She traveled to Europe with a con man called Gonzolo who created the scam of pretending that she was high born, have wealthy and influential men pay court to her, take their letters, and then blackmail the men with them.
She crossed Sharpe's path when the scheme targeted Henry Wellesley, brother of Sir Arthur, and British Ambassador to Spain. Sharpe was dispatched to retrieve the letters Wellesley had written, and having accomplished the greater part of that assignment, he tracked down Caterina who had been hidden away by Lord Pumphrey. She accepted Sharpe had found her out, and admitted that she had more of Wellesley's letters which she had kept as her rainy day fund. She then made him bathe, rinse out his uniform, and go to bed with her.
She told Sharpe of Pumphrey's duplicity when Sharpe had thought the man relatively honest. She then told Sharpe Pumphrey exchanged secrets with her, that he had told her he'd had Astrid killed. Sharpe was furious, but Catarina said he must not kill Pumphrey, since she liked him. Instead, Sharpe told her to hold Pumphrey up for 1,000 guineas for the remaining letters, which Sharpe then burned in front of them both.
She hides among the British soldiers on the Isle de Leon where she creates a new persona for herself. A young widow of some three months, as whom she meets General Moon. After she leaves Sharpe for not being rich enough, she seduces Brigadier General Sir Barnaby Moon whom she met at a dance. He marries her by the end of Sharpe's Fury.