"What I don't understand," the Doctor says conversationally, " is [that] Cybermen don't have the technology to build the Void Ship. That's way beyond you. How did you create that sphere?" The Cyberman admits that it's not theirs, and the Doctor is stunned. "The sphere broke down the barriers between worlds," says the Cyberman. "We only followed. Its origin is unknown." Then what's inside it, wonders the Doctor, starting to panic. "Rose is down there," says Jackie, fear in her voice. If the Cybermen are human evil, the Age of Steel, Victoria's World, coming through across Hell, what could possibly have led the way? Every Companion has her Doctor.
The smartest thing this New Series ever did was put the Doctor/Companion relationship front and center: to interrogate, radicalize, investigate the ways that Doctor and Companion work together. Season 1 was about coming together: raise the Companion ever higher until her power eclipsed the Doctor's for one moment. Everything since then has been an ongoing question of what happens next: the regeneration of the Doctor. The introduction of Torchwood: a reversal of the Doctor and everything he stands for, a linguistic game as much as Bad Wolf ever was. The return to New Earth and Lady Cassandra, to see how much we've changed, and how much more we can touch. The loss of Queen and country, at Torchwood House. The Companion as broken human individual, building a life from scratch. The possibility of love, doors instead of walls. The death of the mother and the loss of a lover, on the other side of Hell. The return to facelessness at the end of the adventure. ACTUAL LITERAL SATAN telling truths nobody wants to hear. The ones left behind, not touched by Companion's magic. The selfishness inherent in Peter Pans, and in their Wendies. And now the grip of history, that black gravity, pulling you back into horror; history nobody can escape, even a Time Lord. It's fun to one-up last season's finale: to say "Instead of one terrifying enemy, we shall have two!" But it's more intelligent to bring back one to fight the Doctor, and one to fight his Companion. The Doctor's fear is extermination of life, his oldest enemy and greatest victim in one. Brutality -- what happens when you draw the line from mercy to justice and just keep drawing, off the page and onto the desk and out into the dark places. But the Companion's fear is different: it's hitting ground, touching the earth again. Dying from the stars: you will be like us. The ramp up and the ramp down. Change feels like death because it is. This story is just as inexorable as last year's, proceeds from its ingredients just as elegantly and just as heartbreakingly; it's just a story nobody wants to hear. "Et in Arcadia, Ego": even in Paradise, there is death. Even the Bad Wolf has to go home sometime, whether or not she's done playing.