"Time can be rewritten." "People can't!"
IN THIS ONE... The Doctor scrooges Michael Gabon. Plus, flying fish, a doomed opera singer, and the Ponds on their honeymoon.
REVIEW: I am an immense fan of Doctor Who's more Christmasy of the Christmas specials, and this despite the Ponds' sidelining (they're trapped in a Star Trek parody, though do get to play the ghosts of Christmas present) and what time travel purists have called a step way over the line into Bill & Ted territory (see Theories for why it doesn't bother me, continuity-wise). In fact, I don't see any of these as weaknesses; they're features. The Doctor's decision to "scrooge" Kazdan Sardick isn't a gratuitous one - it comes to him naturally, from hearing a Christmas carol - and the Dickensian tropes are given some pretty neat twists along the way to keep the story fresh and original, especially older Kazdan as his own ghost of Christmas future. The timey-wimey elements are dead clever throughout, but they're more than cheap tricks. They also matter emotionally - and must, for the story to make sense. Kazdan is a callous, evil man driven by abuse, who finds his soul through his adventures with the Doctor, only to become bitter again, hating the Doctor for tempting him with the unattainable. On a story basis, the changes in the timeline work regardless of what physics you care to invoke because the emotions behind them are coherent.
This is also the most magical of the Christmas episodes, tapping into Moffat's "fairy tale" style via Dickens' fantastical original story. Schools of flying fish, the Doctor riding a carriage through the sky, a beautiful girl with the voice of an angel (don't think we didn't notice how the title took on a different meaning in the climax) who can only live one day a year, and of course, a child taken on adventures in a magical box. As with Amy Pond, the Doctor is that imaginary friend begging to be remembered by Kazdan. Begging? He's positively forcing him to! This is the story of a young boy whose imagination and sense of wonder is being stifled by an overbearing, pragmatic, amoral father, and who, in the original timeline, is denied love. With love comes pain, sure, but it remains the transfomative experience that changes... the boy? the man? That's gloriously ambiguous. At the end, they're the same person, saving the doomed starship by their once and future love. It's grand and beautiful and clever and funny and tragic... Everything I want Doctor Who to be.
THEORIES: So how is this story possible? The Doctor basically goes back in time to change a person's personality, flitting back and forth between the past and the present, and the person is aware their memories are changing. Two explanations come to mind, and a combination of them may be responsible for Kazdan's temporal awareness. First, he's being shown those memories in an old recording. The Doctor makes sure of it, so it must be important to jostle those memories loose decades after his incursion into young Kazdan's life. The recording seems to keep Kazdan in that moment. He doesn't remember all his experiences with the Doctor at once and become a different person; he relives the memories as they concurrently happen in the video. The timey-wimey bit of this equation is that Kazdan soon becomes a time traveller. This might "update" his entire time stream with whatever "patch" makes time travelers remember their original timeline regardless of changes made to it. So the Doctor must have planned to take Kazdan on a trip regardless of what happened on that Christmas Eve long ago. But wait, when Amy's PERSONAL timeline was changed, her memories did too and she forgot her timeline. Ok, but that wasn't permanent. Seeing Rory again, and later seeing a book shaped like a TARDIS, she remembered her other past. Perhaps that's what the recording is for. But bigger picture: There is absolutely no reason for temporal mechanics and limitations to be the same as they were before Big Bang 2. Think about it. This is an entirely different universe that just so happens to have been regrown from particles of the previous universe. Regrown by energy from the TARDIS, the Doctor's TARDIS. That might imply that the TARDIS itself has increased power to change and manipulate "historical" events, cross in and out of its own timeline, etc. These tricks might have been difficult and not at all recommended before, but in a new TARDIS-created universe, the Doctor might have written loop holes in the God Code. So time is more fluid from now on. I'm embracing it.
SECOND OPINIONS: My original review, 10 and 1 Things About Doctor Who's Christmas Carol, makes several more points, if that wasn't obvious from the title.
REWATCHABILITY: High - Just gorgeous. This isn't just my favorite Doctor Who holiday special ever, it's easily one of my favorite Doctor Who stories of all time.