to sacrifice her, taking the forces of anti-time into himself instead. History is then altered so that the paradox of Charley's continued existence became part of established history – in other words, the paradox and the resulting consequences, including the change in the timeline, were supposed to happen. However, having absorbed anti-time, the Doctor now is a danger to the universe, and so has to exile himself into a parallel universe where time does not exist. He intended to do so alone, but Charley stows away aboard the TARDIS and follows him into exile. Eventually, the Doctor discovers he is free of the anti-time infection and he and Charley manage to find their way back, accompanied by C'rizz, a native of that other universe. It is the later death of C'rizz that prompts her decision to leave the TARDIS. She quickly changes her mind but, due to a series of events involving Cybermen, temporal shifts and memory loss, parts company with the Doctor. While he believes she has voluntarily left him, Charley actually ends up marooned on an island in the year 500002, believing that the Doctor had died in their confrontation with the Cybermen. She builds a makeshift crystal telegraph and sends an SOS repeatedly into space, hoping that anyone, particularly the Doctor, would rescue her. When her message is finally answered, it turned out to be the Sixth Doctor who saves her. Charley chose to continue travelling with this earlier incarnation, keeping the circumstances of her past and his future a secret from him. This leads the Doctor to grow suspicious of her secrecy and poorly devised lies. Eventually she runs afoul of a secret TARDIS inhabitant named Mila, who swaps places with her. Charley is infected with a virus rendering her invisible and non-corporeal while Mila pretends to be her. Of the dozens of companions Mila has secretly encountered, Charley is the only one she could infect, because she's the only companion the TARDIS refused to protect from infections. It is implied that the TARDIS hates Charley because of her multiple temporal paradoxes. Charley is cured by the mysterious Viyrans and she spends years helping in their mission to rid the universe of certain viruses. Finally she finds the Sixth Doctor again, still traveling with Mila who is still pretending to be Charley. But Mila dies saving the Doctor's life and Charley takes the opportunity to finally