“The Day of the Doctor” was a wonderful romp, but it was also a quest to the heart of the show. That was inevitable, given the Doctor trifecta. But the episode didn’t hinge on the Doctor, on the influence of the Doctor over himself, or the mighty battles of gods and kings. It hinged on the Companion, on Clara Oswald.
Without Clara–or without an equally great companion in her place–everything would have fallen apart. The Doctor would have committed “a crime that would silence the universe,” murdering billions of children and other innocents. Not only that, but the Doctor would have accepted the choice. Not embraced it…not yet. But we saw what the Time Lord Victorious looked like, and I don’t think anyone would have wanted the Doctor to turn back into that.
Clara looked at one of the most momentous events in history, at a man about to wield power beyond reckoning, and she said no. It wasn’t a loud no, or a furious no. But it was still no.
Clara stood for all great companions, in that moment. She changed the course of the universe’s history. She stopped the Doctor. She saved him from himself, and saved billions from him. And that’s what good companions do. Sure, they ask questions, they enjoy adventures, but at the climactic moments they are the pivot of history. The bond they have forged with the Doctor makes the universe change.
Yet, though companions’ actions shape the universe, they operate on a human level. They make the choices they do–they stop the Doctor and bring him back to himself–not because they are brilliant, or because they are women. It’s because they are human. They feel, they understand, and they make the Doctor better.
There’s a reason, at the end, the War Doctor told Clara he hoped one day to be half the man she was. And there’s a reason the Tenth Doctor told her “It’s good to know my future’s in safe hands. Keep a tight hold on it, Clara.” Because the story may be the Doctor’s but the Companion is its hero.