The second series of Doctor Who has, to date, focused to an unusual degree on a loss of identity by outside influence. It’s been a central plot point in every story: the blood control in The Christmas Invasion, Cassandra’s shenanigans in New Earth, the Werewolf in Tooth and Claw, the children in School Reunion, the repair droids’ use of humans in The Girl in the Fireplace, the Wire’s victims in The Idiot’s Lantern, Toby and the Ood in The Satan Pit, the Abzorbaloff this Saturday — and then there’s all the Cyberman stuff. In each case the victims are robbed of a personality, such that their bodies might be used for other purposes — in most cases, to be physically transformed or integrated into something else.

Then there’s this lesser theme of people with obsessions abandoning them and “moving on”: The Rose with Doctor #9, Cassandra again, Sarah Jane, Mickey. The Doctor keeps half looking for excuses to give up wandering (in both Fireplace and Satan Pit) — or at least, he sure gives up quickly whenever it looks like he’s going to be stuck somewhere. To contrast, there are the characters who insist on clinging to the past — and we see what happens to them: Sarah Jane, who nearly wasted her entire life waiting for the Doctor to return; Reinette, who did. Then there are all the “Doctor Who fans” in Love & Monsters.

And yet there’s this temptation, this constant theme that maybe one can return to the past. That there’s some way to reclaim what you’ve lost: Cassandra and her business with Chip, Victoria and her paranormal mutterings, the Skasis Paradigm, this “before Time” business in The Satan Pit. Though she thought it was behind her, Rose still can’t get over her father and is drawn to his doppelganger. Part of the Doctor’s infatuation with Reinette was in how she managed to help him revisit his old, buried memories. And then there’s “Army of Ghosts”, coming up.

Of course, given that an identity is mostly built up out of memories… this all gets rather complex.

Especially in light of the huge new spoiler that will not be mentioned, I wonder how this all ties into the last couple of episodes. I doubt we’ll see any true conclusion in the next few episodes; these themes seem to be setting up something so huge that it’ll take most of series three to address.