(Please note: due to new information from the latest episode, this theory is out of date. See my next post for my new theory. It also falls apart a little because of a misremembered quote)
(Please also note: this post contains major unshielded spoilers for episodes of Doctor Who through to The Wedding of River Song (2011's final episode). You have been warned).
... on the Fields of Trenzalore, at the fall of the Eleventh, when no creature can speak falsely or fail to answer, a question will be asked — a question that must never be answered. (Dorium Maldovar)
Silence must fall when the Question is asked. (Dorium Maldovar)
Doctor who? (Dorium Maldovar)
So what do we know?
-In The Forest of the Dead, River Song reveals that she knows the Doctor's name. He talks about this with her with no other witnesses, so either he's telling the truth, or he lied to her about his name (in such a way that he would understand the need before he ever met her), or he's lying to us. Let's assume he's telling the truth.
-In The Pandorica Opens, the TARDIS was grumbly from the beginning (ie, the time they landed in or set off for Roman Britain). When the Doctor sent River off alone in it, she reached Amy’s Time (with grumbling), found out what was going on, and was trying to get back to the Doctor when she found herself locked in (by a stone wall outside the doors). The TARDIS then blew up.
-In The Big Bang, one of the last things we hear is an ominous voice declaring ‘Silence will fall’. This had been a refrain from the beginning of the series, and seemed to be linked to the cracks.
-In The Wedding of River Song we find out that a) River doesn’t know the Doctor’s name yet (unless she lied about lying, of course), b) that the Doctor revealing his name (to River or anyone else) would be essential to them being married (again, unless the Doctor lies), and c) the question is ‘Doctor who?’.
And one more quote...
This I have forseen, in the wild and the wind; the Doctor will be here as witness at the end of everything. The Doctor and his precious Children of Time! And one of them will die! (Dalek Caan)
Who says Caan had a clue what he was talking about? He thought he was referring to the events of Journey's End, but he was insane. What if that prophecy is yet to be fulfilled? I propose that there is a prophecy, known to the Silence, that one known as 'the Child of Time' will bring destruction down on their heads. We know they have prophecies - the Trenzalore quote above is proof of that - so this isn't too big a stretch.
And the Silence think the Child is the child of River Song and the Doctor. We already know they have an interest in children. They are doing their level best to prevent that child ever being born - to prevent the Doctor and River ever marrying.
- In The Pandorica Opens, they (through their manipulation of the Doctor's enemies) tried to get the Doctor locked up forever, while River got stuck in the TARDIS and exploded - vanished from creation, in theory. Did they know that the universe would die when they did this? If so, did they consider that an acceptable price? Remember, the TARDIS' explosion was not caused by the Doctor's alliance of enemies, and hasn't been explained to date...
- In 'A Good Man Goes To War, the Silence steal River as a baby and program her as a Doctor-killer.
- In The Wedding of River Song, they try very hard to get River to kill the Doctor - and as far as they know, they succeed.
But they've failed at every turn. And it wouldn't even matter if they succeeded - because they don't understand the prophecy.
The core difference between the proposed Silence prophecy and the attested Caan prophecy is that Dalek Caan speaks in the plural. There are multiple people who could lay claim to the title Child of Time. For example:
-The Doctor himself. He may be disallowed by the wording of the Caan prophecy, though. (This is the point where my misremembering of the prophecy comes back to bite me - it's only now that I'm aware of the separation of the Doctor from the Children).
-River Song, 'the child of the TARDIS'. It's possible the Silence thought of this and subverted her in an effort to disallow it - but did they succeed?
-Jenny, the Doctor's Daughter - the character who Steven Moffat specifically requested should not stay dead - the sort-of-Time-Lord.
-Amy Pond, with 'all of time seeping in through the crack in her wall'.
-Heck, Rory Williams, probably the oldest person in the universe, what with 2000 years of standing outside a box under his belt.
And that's just the ones I can come up with off the top of my head. The Master? Anyone who has escaped the Time War (and there's been a few)? The list goes on.
And the Children of Time will gather... and one of them will die. On the Fields of Trenzalore, at the fall of the Eleventh...
At any rate, it's far more interesting than 'Le gasp! The Doctor is actually Stalitler!' Or even 'Oh, yeah, Doctor who? I'm actually Omega/Rassilon/the Master.'
(As a note to which: I'd place my money on Omega. There's already been an instance of him trying to steal the Doctor's body - and we know Rassilon came back to life in the Time War)
... but all of this is superceded by my new theory. See next post.