When Mary says "Who you really are doesn't matter"

 (Sherlock meta by Ivy Blossom)

Q: [...] How do you read Mary's presiding over the last minutes of The Final Problem in that context, saying that who Sherlock and John 'really' are doesn't matter and only their adventures do...?

A: This is how I read the sort of unfortunately-worded “it doesn’t matter who you really are” line:

The theme of Sherlock as an entire four series arc is that Sherlock both is and isn’t what he says he is. He isn’t a sociopath, but he is a brilliant consulting detective who solves crimes for fun. Sherlock’s actual self, the one he himself didn’t entirely understand until the end, is not what the legend suggests that he is, but that doesn’t matter. Sherlock is actually a loving and sweet man, deeply and probably permanently traumatized by the events of his childhood. His greatness isn’t impaired by the fact that he’s the product of tragedy, that his desire to solve puzzles and crimes is a psychological wound that he picks at and worries endlessly, or that he can see through others but couldn’t see into himself. That’s not something he’s going to show off to the world, and not really something he wants people to know. That’s private, and that’s okay. He’s allowed his privacy. His greatness and his legend isn’t impaired by the fact that it’s a little bit fake. Because it’s fake in a way that is still actually true.

And we learned in this series that the same is true for John. He too isn’t what he appears to be. He’s a war hero, a moral compass, the angel on Sherlock’s shoulder, but he is capable of great cruelty, betrayal, and violence. Like Sherlock, John is permanently broken. To Sherlock, he is a conductor of light, the person who leads him to do the right thing. John is capable of profoundly failing on the moral front, but again, it doesn’t matter, it doesn’t detract from what he’s capable of. He still is what he is, he conducts light all the same. In spite of the failures that demonstrate how much John is as much of a fake as Sherlock is, it’s him who transforms Sherlock into a good man he is capable of being, and it’s John who brings him peace. Even mired in the depths of his faults, John makes Sherlock better.

I’m not bothered by Mary narrating this, personally. Here’s what: a final narration can’t be John, and it can’t be Sherlock. It’s about them, not about just Sherlock, and that needs to be one step removed. It can’t be a conversation between them, either. I feel like we got the last of the frank conversations between Sherlock and John in The Lying Detective, and every other intimate conversation they have is going to be behind closed doors.

Someone had to narrate it. It’s an echo of Mycroft’s narration of what might become of them at the end of A Study in Pink. I suppose it could have been Mycroft again at the end. Mary threw herself into a bullet; I guess that final narration helps explain why she did that, why John being with Sherlock was so important. It’s because the legend is the two of them in a scruffy flat, ready to help the desperate, the unloved, the persecuted, now and always. She saw that, and she helps them to see that. And so they are.