I've written a rather long analysis about the probable identity of the little girl in The Impossible Astronaut/Day of the Moon which I'd like to share. It's under the cut, but before you click, a somewhat strange disclaimer:
This is an analysis based on symbolism, running themes, patterns in Moffat's writing, and comparisons to other Moffat works--a style of prediction that has proven valuable so far with this show. Three quarters of the way through last season this kind of analysis would say (with no idea as to how any of this would happen) that the Doctor would heal the universe and Amy by sacrificing himself to the cracks, that he would then be brought back to life through the combined auspices of Amy and River, and that Amy and Rory would get married for a happy ending. I don't want to over-sell this or to be over-confident (and, actually, I'm quite nervous about posting this), but please do take that into consideration before reading and decide if that's the kind of thing you'd like to know. This is not the sort of plot-based speculation that usually goes on in fandom.
Right: SPOILERS THROUGH THE ALMOST PEOPLE (AND THE PREQUEL TO THE FINALE), AND PLEASE NO FUTURE SPOILERS IN THE COMMENTS.
Long story short: I believe the little girl who regenerated at the end of the season opener is the Doctor and River's child from his personal future. [ETA: Just to clarify, since everybody is busy thinking about Amy's baby right now. This would mean that Amy's baby is NOT the one from the season opener and that there are in fact two babies in this story.] Anyway I have reasons:
1) Why are so few people wondering if this is a possibility? One Time Lord left in the universe and suddenly there's a little girl running around with an ability to regenerate. Where did she come from? Lay aside your prejudices as a Doctor Who viewer for a moment and try to think about it in an in-world manner: what's the most straightforward explanation for her existence? Ok, now tell me why the most straightforward explanation is one I've hardly even seen brought up? Heck, I'd call myself a hardcore shipper, and the thought didn't even occur to me until two weeks ago. I've barely seen any discussion of it as a possibility. Even if you don't like the idea, surely it's one that deserves to be in the mix of speculation alongside all the talk of timeheads and fobwatches and alien-engineered babies, and yet . . . ? I wonder if we're not coming up against our collective sense as fans and television viewers that "they're not allowed to do that." In fact, it's an attitude I did see expressed a lot after The Impossible Astronaut when people were talking about Amy's nausea--they would bring up River's similar bought of stomach-clutching as evidence that it was a result of seeing a Silent and almost immediately follow it with "unless River's pregnant too--BUT THEY'D BETTER NOT DO THAT!" Well, Moffat's given us River Song, Amy jumping the Doc's bones at teatime, a pregnant companion . . . his respect for "not allowed to do that" seems pretty minimal. And he's told us he's writing game-changers this season.
2) If this were just any show that Moffat was writing without a fifty year franchise history to take into consideration, I would be shocked if that little girl wasn't the Doctor and River's. All writers have their things and this is very much Moffat's. [Quote of Moff's supplied by
owlsie : Russell reckons it's all about parenthood with me. It's his view that every writer has one story that they go on re-telling, and that being a father is mine.]
3) Season five has taught me to trust the symbolism. Symbolism said Amy and Rory would get married. Symbolism said the Doctor would fix the universe and Amy by sacrificing himself to the cracks and that he would then be brought back to life through the combined auspices of Amy and River. The symbolism says the story of Eleven and Amy is the story about how
both of them will grow up. And the symbolism around the Doctor/River relationship is
CRAMMED FULL of parental tropes. Now, I was perfectly happy to accept all that in an abstract kind of sense in which the Doctor and River serve as a metaphorical mum and dad to the universe (see their matching "bedtime story" scenes in Forests of the Dead and The Big Bang, for example) and with Amy as a stand-in daughter figure, but that was before there was a six year old running around with an ability to regenerate. And, frankly, River in particular has so much fertility symbolism going on around her that it all starts to feel a little bit . . . empty if it's all strictly symbolic. For anyone who's going to ask me questions about how I think a plotline about a Doctor/River child would work out: I have no idea. But then, last season Rory was dead and the only sure thing was that he would marry Amy. I'm pretty sure nobody could have predicted that that would happen by him coming back as a plastic replica of himself, shooting Amy, waiting 2,000 years with her in a box so she could be brought back to life, and then the entire universe being re-made so that he could be a real boy again, but it all worked out in the end. Keep your eyes on the big ideas and Moffat with take care of the technicalities.
4) SPOILERS FOR JEKYLL. So a few years ago Moffat wrote this six-episode television show called Jekyll, which is a modern re-imagining of the story of Jekyll and Hyde. At its heart, it is a six-hour long elaboration of what went down between River and the Dalek: mess with my family and I will FUCK YOUR SHIT UP. Moffat is already borrowing heavily from Jekyll for the Doctor/River storyline, including playing with ideas of dual identity, putting people in stasis boxes, a woman married to a man who takes different forms, cyclical god/goddess symbolism, the connections between violence and love . . . even apples. And the only major component that's missing is children. But that's a huge, central component. So much so that I was looking at bits of River's actions last year like the scene with the Dalek and going 'this makes better Moff-sense if there are kids at stake.' In Jekyll, the main character's children are stolen by an evil corporation that's been directing his life in the hopes of using them to gain control of the super-human powers of Hyde . . . so why do you think the Silence are interested in little Time Girl? What did River say about why you can't leave Time Lord bodies lying around?
5) A storyline in which future!Doctor and future!River's daughter has been stolen by the Silence in order to steal her Time Lord-y powers, possibly controlled/altered by them in some way, and current!Doctor and current!River have to discover who she is and acknowledge her in order to save her (and the universe), thus claiming their own identities in the process hits . . . approximately every Moffat narrative checkbox ever. Especially ones about stolen/estranged/altered children and about discovering and acknowledging hidden family connections being the key to resolving whole multi-threaded storylines (see, for example, Nancy and Jamie in The Doctor Dances, or Mr. Lux and CAL in Forests of the Dead, or even Amy and her missing parents last season). Also, this season we have already had two separate episodes in which accepting sudden parenthood is a major component not just of the episode itself, but in the resolution of the problems in the plot (Captain Avery in the pirate episode, and the ganger and his son Adam in last week's episode). In both cases, it was not Amy and Rory standing around on the sidelines with a lot of lingering shots of them watching thoughtfully . . . just saying.
6) On the topic of discovering hidden family connections.
owlsie had this to say: Moffat would absolutely, totally, 100% try to make us think that it's all about Amy's kid when PSYCH THE WHOLE TIME IT WAS REALLY ABOUT THE DOCTOR'S KID AND AMY'S PREGNANCY IS A DIFFERENT PLOT THREAD ENTIRELY. The blatantly manipulative head writer of this show has had the blatantly manipulative alien menace put a photo of Amy with a baby in a kid's room and fandom is taking that as more reliable proof of parentage than an ability to regenerate? The show even went out of its way with the whole voice recorder 'oh no, does Amy actually love the Doctor not Rory why did she tell the Doctor about her pregnancy before Rory?' thing to discount the possibility that Amy's child is the Doctor's. [ETA: Oh, and the prequel for the next episode teased that idea as well, with it's rather vague wording about "whose child"--prompting new questions about whether Amy could be carrying the Doctor's baby. But . . . adultery, really? Or, what, Amy's captors made a timebaby with the Doc's DNA and impregnated Amy with it? Is either of those a line the show would really cross? There's squicky and then there's squicky.] But nobody's bothering to ask how the girl who regenerated might be the Doctor's in some other way? If this is narrative misdirection, it's working fabulously. Moff also recently and rather cheekily tweeted that his kid
worked out the whole season in between the girl regenerating and the end of the credits. I don't care how gifted his son is, that means the answer is at least a simple one.
7) How did Moff get us all (and, not coincidentally, the Doctor) to accept the idea that the Doctor could actually have a wife? He presented her as a fait accompli, let everybody freak out for awhile, and then it all settled down and three years later we have the impossible: a majority of the audience are going to tell you 'of course she's his wife!' Why not pull the same trick with a kid? Also, Moffat has been using the Amy/Rory relationship to parallel the Doctor/River one, especially in the way it parallelled Amy's and the Doctor's fears and reluctance about their futures. This season we've started getting parallels between Rory and River. If there's a baby in one storyline, we should be asking ourselves if there's another one too.
8) NARRATIVE IRONY. Watch the scene with the Doctor and River examining the astronaut suit and talking about the little girl but make the assumption that they are unknowingly talking about their own child. It starts to feel very like the scenes in The Pandorica Opens where they're trying to figure out what's in the box and the Doctor keeps not realizing that he's talking about himself. "I have the strangest feeling she's going to find us." Ditto the end of the episode: "So, this little girl, then. It's all about her. Why is she important?"
9) Music: watch The Impossible Astronaut and Day of the Moon. It's the same distinctive, haunting music playing over the Doctor's death, the Doctor/River kiss, and the little girl's regeneration. And I think those are the only places we've heard it so far. I can see why you might use the same music for the death and the regeneration, but why the kiss? Murray Gold is--how shall I put this?--not subtle in his musical cues.
elisi points out that back in season three, in the episode Utopia: 'This is Gallifrey: Our Childhood, Our Home' is ALL OVER Yana and Doctor/Yana. It's so unsubtle it's really very funny. In other words, before we even knew he was the Master, the music was screaming that this guy was a Time Lord.
Alright, time to wrap this up. It's not like I'm putting money on this or anything, but in all the ways that it's possible to predict a Moffat plotline, I think it all fits rather well, and I'm still trying to come to terms with why I'm not even seeing much speculation to this effect.
Originally posted (with some edits)
here at my journal, if you want to read some more comments.
ETA: Anybody who is worried about the question of how the Doctor and River could allow their daughter to get stolen away (or about why River's whole sudden back-to-front timeline MAKES NO SENSE)
this is my current pet theory, although mostly I'm still sticking to my assertion that there's no real way to guess what mechanics the Moff will use to make anything work.
PLEASE NO FUTURE SPOILERS IN THE COMMENTS.