Brianna (Hydra's Gate)

Brianna was a young woman from 2022 Earth who went mysteriously missing one day, leading the Thirteenth Doctor, Yaz, and Dan to try and track her down. Eventually, it was revealed that she was one of several over time who had accidentally entered a pocket universe through a portal hidden underneath Hydra Hall. The Doctor managed to rescue her and the others from the pocket universe and reunite her with her mother. (COMIC: Hydra's Gate)