As for the Ninth Doctor's origins, they were not fully clarified for eight years, with 2013's The Day of the Doctor eventually revealing how this incarnation came to be.
Rose Tyler wakes up one morning, gets ready for work, and kisses her mother Jackie goodbye.
Indeed, Rose started a mild story arc surrounding the mystery — from Rose's perspective — about the Doctor's identity.
New audiences would not have known until the series' final episode that the Doctor could regenerate, and wouldn't get their first glimpse of other Doctors until two years later, in Human Nature.
He peers behind the sofa, and is attacked by the arm.
Rose notices the strangulation, but ignores it, thinking it a jest — that is until it lets go and flies towards her.
Once she's at a safe distance, she watches in shock as Henrik's explodes in a huge ball of flame. She returns home, and her boyfriend Mickey Smith comes in to check she's okay.The next morning, Rose awakens, before realising that she no longer has a job to go to.Walking around the house, she suddenly hears a scratching noise from the cat flap.She assumes her mother hasn't screwed it shut, and that it's a stray cat.She opens it up to find the Doctor; he tells her he's been tracing a signal from the plastic arm. While Rose is making the tea, he explores the room, and looks in the mirror and is stunned by the size of his ears, implying he has recently regenerated.