After a brilliant but troubled two years heading toward an engineering specialty at Starfleet Academy, subject Torres seemed to be constantly at odds with the Klingon heritage of her maternal side and after several disruptive episodes agreed to leave school. Having grown up on Kessik IV, where she and her mother were the only Klingon residents, her human father left when she was a child, and she has always blamed her Klingon heritage for driving him away.
She later joined the Maquis rebellion in its early stages and by mid-2370 was acting as engineer for former Starfleet officer Chakotay's crew. When the Maquis crew merged with Voyager, she sucessfully became the ships chief engineer. She has been described by her captain as tough, knowledgeable and independent.
From The Official Star Trek Website