NOTE: The following post contains SPOILERS for Doctor Who season 9
After a year of big transition, with Peter Capaldi taking over for Matt Smith as the titular Time Lord, showrunner Steven Moffat has hit his stride with Doctor Who season 9. No doubt, some fans remain underwhelmed by Moffat's tenure as lead writer on the series; however, many are relishing in what the producer has put together this series. Aside from a few episodes that were mostly par for the course, the season's reliance on two-parter stories has resulted in several standout tales that are among the modern series' best.
This week's episode "Heaven Sent," which saw the Doctor trapped in a prison designed especially for him, was especially well-received - and the story's cliffhanger ending raises interesting implications for where the series will go in the finale (as well as upcoming Christmas Special). Fans will need to tune into the series 9 finale, "Hell Bent," to see exactly how The Doctor resolves his current crisis but, thanks to an official announcement from BBC, we know surface-level details of what the Time Lord will face in the 2015 Christmas Special - as well as who will be joining The Doctor for his next holiday adventure.
Previously Moffat had revealed that River Song (played by Alex Kingston) would be returning to the show, for her first encounter with the Twelfth Doctor, and now the showrunner is opening-up about why he decided to bring the character back as well as where the 2015 Christmas Special will fall in her timeline.
In an interview with Radio Times, Moffat explained the decision to bring River back was two-fold: to delay the introduction of a new companion until series 10 and, simply, because Moffat missed writing the character:
Obviously, we’ve just lost Clara so I didn’t want to go straight into a new companion, and it’s not right to set that up at the end of a series where you’re all exhausted. So, I’ll be honest, I brought River Song back in because I thought there’s a possibility I’d never write it [Doctor Who] again so that’ll be my goodbye. But also I really fancied it. I hadn’t written River for a couple of years and I’d always loved writing for her and I’d missed her. I thought, given that I’m knackered at the end of a series, what would be a treat for me would be getting Alex Kingston back onto Doctor Who.
Moffat indicates that it doesn't really matter where the Christmas Special falls in River's timeline (meaning that casual viewers won't need to brush-up on the previous adventures of Dr. Song to enjoy the upcoming episode); yet, the showrunner does know exactly where the 2015 holiday tale lands in River's chronology:
It doesn’t really matter but for those who care, it’s immediately after The Angels Take Manhattan  so she’s just seen Matt Smith’s Doctor lose Amy and Rory, and obviously before The Name of the Doctor  because she’s dead in that.
The writer also confirms that, after such a dark and emotionally taxing run of episodes at the end of series 9, the Christmas Special would be slightly lighter in tone (though still befitting of the current storyline):
It’s towards the comedy thriller end of the Doctor Who market. It’s light, and quite emotional at the end. The big deal is Doctor No 12 encountering River and vice versa. It’s strange because they’re now, in our human terms, the perfect couple. They’re both sexy older people. It’s always been slightly strange before with Matt [Smith]. Now, yeah, they could actually be married. It works. She’s great with Peter [Capaldi]. She genuinely hasn’t aged a day since she did The Silence in the Library [her debut story], which we made in 2007. She looks amazing. She totally gets how to do that part. And she’s very, very funny.
It’s a great romp for Christmas day but – and you’ll be pleased – there’s not a lot of Christmas in it. It starts with a big bit of Christmas at the beginning and then we ignore it and go off on a chase, really, with Mr & Mrs Who. One thing worth saying about it is, if you’re a long-term fan of the show, you might be interested because there’s been a lot of talk about the Doctor and River’s glory years but we’ve never seen them. Here at last we see them as Mr & Mrs Who at the height of their powers. It’s great fun.
No doubt, with Moffat and his team still developing the series 10 companion storyline, River Song is the perfect distraction - to help both The Doctor and fans move forward without being too sad about Clara Oswald (especially on Christmas).
While the casting of an "older" Doctor may have been divisive two years ago, as Moffat indicates, Capaldi could actually be a slightly better fit for Kingston's River Song - in traditional human age terms. Thanks to a great performance, Capaldi has won-over a lot of detractors who were (understandably) hoping for a younger, non-white, or female performer in the title role, and seeing the actor's gruff Doctor share the screen with River Song should make for an entertaining dynamic - especially since River is one of the only characters in the series that can knock the Doctor down a peg.
Additionally, placement of the story within River Song's chronology should provide an interesting pairing - since The Doctor will still be reeling from the loss of Clara and River will have just seen her own parents (Amy and Rory) transported back in time by the weeping angels (separated for eternity from the Eleventh Doctor). To that end, it shouldn't be too surprising that the episode is Christmas-lite - focusing more on the shared adventuring of River and the Doctor, rather than a heavy-handed holiday tale.
That all said, while Moffat and his team have all the necessary pieces for a fun (and heartfelt) Doctor Who Christmas Special, little is actually known about the episode. Previously, BBC released an official synopsis, promising "a frantic chase across the galaxy" with an out-of-control "giant Robot bodyguard" and "a destination the Doctor has been avoiding for a very long time,” but Moffat has remained mum on whether the Doctor and River's new adventure will have lasting implications or simply be a one-off tale. One thing we do know: River won't initially recognize this Doctor - affording the Time Lord a rare chance to know more about his timeline than his wife.
Since "Hell Bent" airs in less than a week, with the holiday episode set to premiere only two weeks later, it's safe to expect a Christmas Special teaser trailer is forthcoming - with the likely possibility that fans could even get a direct link between series 9 and the holiday episode in an epilogue to the season finale.
Doctor Who airs this week on BBC1 and BBC America with “Hell Bent” and will return on December 25, 2015 for this year's Christmas Special.
Source: Radio Times