The TARDIS "family" seems to be very dysfunctional, in "Doctor Who", under the guidance of Russell T Davies! The departure of Mickey, at the end of "The Age of Steel", means that Rose has seen off no less then three male companions in the space of just twenty episodes, less if you take into consideration that the first of this triumvirate, Adam, only joined the crew at the end of "Dalek", last year's sixth episode. He was dumped a week later, in, for him, the inappropriately titled "The Long Game", and after Rose redeemed her Dad in "Father's Day", Captain Jack hopped on board in the tenth episode, "The Doctor Dances"!
Jack Harkness lasted all of another three weeks before being killed off, brought back to life, then left behind in the appropriately titled final episode of the first season, "The Parting of the Ways"! And now, last year's finale has essentially been remade, not just with the Cyber Controller replacing the Emperor Dalek in grandiosity, but by following the death of Ricky with his "rebirth" in Mickey and, this time, having the companion opting to stay behind after another similarly short stay aboard the Doctor's transcendental ship.
With a similar dynamic, I can think of only one other companion who has remained in the series through the successive terms of three other companions of the opposite sex and his name was Jamie. But at least Polly, Victoria and Zoe lasted, approximately, a whole season each, and in the Sixties a season meant a season! The programme was, virtually, on screen all year round. These days, you get the feeling we are being treated to bite-size companions, to go with our beloved chips! I have wondered if Russell wants to work through as many combinations as possible, as quickly as possible, in case it should all end tomorrow! The original, so-called "classic", series ran for twenty-six seasons. I know it's all relative but that really was playing "The Long Game"!
One of the interesting things about the recent two-part Cybermen story was an acknowledgement that the creatures had only been defeated in London. In previous "classic" adventures, it was always understood by the viewer that once victory over an enemy is attained, the triumph is worldwide. Presuming Cybus Industries are global, as we are told, surely the irony of the conclusion of "The Age of Steel" is that the signal from Rose's mobile phone would have disenabled the entire Cyber force. For once, there is the means to accomplish what was always assumed but it isn't acted upon, in favour of sending Mickey off, in his new role as freedom fighter, to Paris, for some unexplained reason, to have a go at the French Cybermen! Perhaps he was taken by his all-too-brief meeting with mistress Madame Reinette a couple of weeks ago!!