When the Doctor first met her, Rose was a nineteen-year-old living on a London council estate who had left school with little educational achievement. Emotionally shaped by living with a promiscuous mother and stories about a father whom she never knew, Rose seemed destined for a life as a retail worker.
Instead, the Doctor blew up her workplace and they began travelling together soon afterwards. Without trying, she helped the Doctor work through some of the pain he had as the sole survivor of the Last Great Time War. Indeed, when she met the Doctor, she was the girlfriend of Mickey Smith, but that relationship immediately began to decay after she started travelling in the TARDIS. As Mickey himself noted, she transferred her romantic attention to the Doctor.
A major facet of her travels in the TARDIS was the fact that she had caused a temporal paradox by which she was the reason she became the so-called "Bad Wolf". Leaving herself a trail of clues throughout history, she was able to recognise, when all her hope had evaporated, that she needed to find her way back to the Doctor — even though he had abandoned her and the TARDIS together. Unable to actually fly the time machine, she was forced to simply stare into its heart, which enfolded her in time vortex energy and turned her into a new and seemingly omnipotent being that could rescue the Doctor. But it also nearly killed her. Only the Ninth Doctor could absorb the time vortex energy and transfer it back to the TARDIS — a traumatic act that naturally triggered regeneration. She thus became one of only three companions — along with Peri Brown and Wilfred Mott — to be the proximate cause of the Doctor's regeneration.
Forced to stop travelling with the Tenth Doctor because she was literally pulled into a different universe, she spent years trying to find a way back to the Doctor. Although she found one, the Doctor explained that she had to remain in her new universe with her mother, brother, that universe's Pete Tyler and, for a time, Mickey. Ultimately, her wish was fulfilled when a human Tenth Doctor came to reside there with her.