Who Spoilers ahoy
"A press-only trailer for the series showed Penelope Wilton reprising her role as Harriet Jones, and the main antagonist of the series having the lower half Dalek and the upper half humanoid"
More on the launch night
So there we are. It's basically Davros, but how? Hmmm. OK, maybe the Cult of Skaro (the last guy) is recreating Davros in Ben Kingsley's David Bowie's a new body and downloaded a copy of his mind which was either held in the Cult members memory banks or extrapolated from Dalek history files. Nu-Davros then gives instructions and they begin building a Dalek army again or rescuing the thousands of Daleks from limbo. The more I think about it, the more I love the idea of the Dalek(s) grabbing a genius and turning him into Nu-Davros.
Having an alternate Davros is far too close to the Cyberman story, so let's ignore that. Going back in time to when Davros is 'human' looking Kaled is also pretty dull and just opens a can of worms since it almost certainly has to be a 'fixed' event.
The last we saw of the modern Davros, he was the Dalek emperor, just a head, and in an escape pod. In orbit of 1963 Earth. Of course we don't know if that had the ability to time travel, since he'd used time corridor technology to get to 1963 in the first place. Given the evolution of his own body and the enormous baggage factor of Dalek history if the Davros that returns is the modern Davros, I'm going with it not being him: he's dead and gone in the Time War.
So.. a recreated Davros in his classic body with just enough memories to know and hate the Doctor. Nice and new-viewer friendly. Sorted.
But where does he fit into things? He'll be in the finale. Which means it'll almost certainly have something to do with Rose appearing and the barrier between 'alternative's becoming weaker/breaking down after the explosion in Saturday's episode. While the cult of Skaro is aware of parallel universes, I think the focus will be on rescuing the (pure) Dalek army from limbo rather than invading Rose's Earth or reheating that Cybermen story.
"Main antagonist" implies he'll be at least heavily foreshadowed if not appearing earlier than the finale in its run. Will he have something to do with the Sontarans? I'm guessing no and he'll be referenced somehow in episode 6 given it involved 'building' a new person through some kind of cloning. (I still don't think Davros will be cloned - I think it's cooler to inflict it on someone we meet and like before it happens).
The jury's out about Moffat's two parter. It stars Colin Salmon, the recognisable guy from Resident Evil and supporting role in Brosnan's run as Bond. No mention of the two famous Davros potentials in the cast. In any event, I don't think Moffat would do a Dalek story since he's too original for that and likes to do his own thing.
So we've got episode 10, Midnight. It's about a pleasure planet. This could easily involve more set-up and advancement of the Davros plot with some obvious lines like using human bodies etc etc. I think again it'll have a scene or so of set up for the finale rather than it being a Dalek plot in itself.
The finale is likely, again, to be a 3 parter. RTD has not learned from last year then. At least we'll likely get a great episode like Utopia.
OK, let's recap the theory:
The last member of the Cult of Skaro grabs a genius (played by a famous guest star, at least initially), and uses his body and brain to create Nu-Davros to lead the Daleks to supremacy. The main plot will involve trying to rescue the Dalek army from limbo now that the barriers between worlds are weakening again. 3 part finale; he'll be in at least the last episode properly, probably showing up at the climax of episode 12 as a "surprise" and foreshadowed post-Sontarans in episodes 6 and 10.
Wildcard: what about the thousands of Cybermen who are also trapped in limbo?
Right, enough for me just now. I need to iron some shirts. Might have another think while I'm doing it.