Moira (Shadow World)

You may be looking for the person this construct is based on.

Moira existed as virtual construct in a world created by the Monks, so that they could plan the perfect invasion of Earth.

Moira shared the history and personality of her non-virtual counterpart, only parting with that history from her perspective in 2017. She was a perfect duplicate and, like the rest of the people living within the Shadow World, she believed herself to be real.

History

In a Shadow World simulation, Bill brought a date home, Penny, as she thought Moira would be out with Harry, who was actually named Howard. When she heard voices, Moira thought Bill had brought "some terrified man" home, and thought nothing of it once she saw Penny. She then left for the pub, telling Bill, "Don't do anything I wouldn't do," which Bill quietly doubted. (TV: Extremis)