The new assistant has three modes: Running around with an idiotic , I've just made luv, smile on her face , puzzled farawy, navel gaze as her single brain cell vainly tries to comprehend her mobile phone, puppy dog gazing at the Doctor who is clearly an ugly wierdo alien - however since her last marriage I can't blame her on that.
Lol.In the first episode it was explained that the Earth revolved around the Doctor and his choices.
Some wag in the press noted that Billie piper was used to being around Men in that position.