Rose Tyler wanted to escape her humdrum life. Martha Jones fell in love with the Doctor. Donna Noble realised that she was bigger on the inside. Amy Pond imprinted early on her Raggedy Man. Clara Oswald saved the Doctor by being everything, everywhere, all at once. Ruby Sunday had an origin mystery to solveEvery Nu-Who companion has their reason for travelling on the TARDIS, but new companion Belinda Chandras is different from most: shes there so that she can leave. The new series tagline Get Her Home is Belindas story arc. She doesnt board the TARDIS excitedly to travel with the Doctor, but reluctantly, in order to get back to Earth. As she tells him in the series 15 trailer, shes not one of the Doctors adventures.Writing in the latest edition of Doctor Who Magazine, Davies likens new companion Belinda (whose surname was originally Finch before Boom guest star Varada Sethu was cast in the role) to the situation of some of the Doctors past pals: Its a play on Ian and Barbara and Tegan the companion desperate to get home.It gives Belinda something to spark up against the Doctor. Shes not in love with his life or with the TARDIS, but the whole thing works because of course she starts enjoying it. She thinks theyre wonderful, and eventually admits it. But its a different kind of buzz it stretches different muscles. Its a performance thing too. Janet Fielding did it brilliantly with Tegan.Some force beyond the universe though, is stopping the TARDIS from getting Belinda home, which means that Doctor Who, as showrunner Russell T Davies explains in DWM, has been forced to skip an essential element this time around.Of course it means keeping the TARDIS away from modern-day Earth. Normally, I think you should keep revisiting the present day its essential. So its been a real challenge to avoid it for an entire series.Interesting! The series 15 trailer definitely shows modern-day Earth characters Ruby Sunday, Kate Lethbridge-Stewart, Mel Bush and more. So does that mean their episode will be this series Doctor-lite adventure? Millie Gibson handled the Doctors absence (due to Ncuti Gatwas filming commitments on Netflixs Sex Education) with aplomb in last years 73 Yards, which also featured UNIT who are also going to have to cope without the Doctor in new spinoff The War Between the Land and the Sea.We know that the Doctor will be on Earth for episode two Lux, which is set in 1950s Miami, and in the Nigerian-set episode five The Story & The Engine, which will presumably also will take place in the past. The series finale The Reality War also looks as though its set in Londons Hackney, but we must be talking an alternative reality to the one Belindas from.Modern-day Earth episodes have been a Russell T Davies staple since Autons menaced Henriks department store in 2005 series opener Rose. It just goes to show with Doctor Who that theres always something new under the sun(s).Doctor Who series 15/season two starts on BBC One and iPlayer at 8am in the UK, and on Disney+ around the world on Saturday April 12.