Why John married Mary 

(Sherlock Meta by Ivy Blossom)

There is no earthly reason for John not to get married, and many good reasons why he should.

John fell in love with Mary while Sherlock was gone, and like Sherlock did before her, Mary probably kept John from seriously contemplating suicide. John isn’t good on his own. He’s lopsided that way, he needs someone else in his life to keep him from collapsing. He hands his heart to very few, but he must hand his heart to someone if he is to survive.

Sherlock’s death, and more importantly, his return, underscore the fact that Sherlock is the wrong person for John to hand his heart to.

John absolutely wants Sherlock back in his life at the beginning of series 3, but if he’s going to go down that road again, he’s going to have to do it properly. He can’t let Sherlock be his entire world, not again. It’s way too dangerous. John has trust issues, after all. But beyond that: John isn’t going to offer more to Sherlock than Sherlock has demonstrated that he’s willing to take.

John appeared to have reconciled himself to being in a non-sexual but monogamous and committed whatever-the-hell-it-is/relationship with Sherlock in series 2. John starts out dating every woman who will have him, then stops when he realizes that his heart’s not in it. They’re all just elements of his denial of the fact that Sherlock is his primary emotional connection.

John accepts Irene’s interpretation of their relationship. When they’re in Baskerville, he doesn’t deny that he and Sherlock are a couple, even though he still wants to explain that it’s not that kind of relationship, in that they’re not sleeping together. But he stops trying to explain. I don’t know if he even can explain. Possibly he’s realized that it doesn’t matter, and it certainly doesn’t matter what other people think. But he stops trying to pretend this relationship isn’t happening, whatever it is. Irene’s right: they are a couple, and that’s how John’s decided to behave. John loves Sherlock with his whole heart. John is okay with their odd pairing through series 2. He’s made his choice, and his choice is Sherlock.

But by series 3, they’ve broken up. Sherlock demonstrated to John in a viciously visceral way that he has a completely different interpretation of their unspoken bond. From John’s perspective, Sherlock’s fake death and silly return were nothing if not an overwhelmingly clear statement that John’s feelings for Sherlock aren’t reciprocated. He isn’t at the centre of Sherlock universe in the way that Sherlock is at the centre of John’s. Obviously! Or Sherlock wouldn’t have lied! He wouldn’t have left John like that, to suffer! Sherlock is the one who broke them up. Sherlock unintentionally and unwittingly dumped John.

But John still doesn’t back off, in spite of all that. He still wants Sherlock in his life, rejection and all.

The wisest thing for John to do is to drop Sherlock altogether. But he can’t, and he won’t. So the next best thing he can do, both to protect himself and to equalize his relationship with his ex who also happens to be his best friend, is to have someone else in his life who loves him reciprocally and will put him at the centre (that’s Mary). Sherlock and John can be friends, they can even be best friends and soulmates, but John won’t make the mistake of committing himself (in whatever queerplatonic way Sherlock can manage) to Sherlock again. (Well, not yet, anyway. I will put money on him taking that challenge on again.)

Getting married is pretty much the best plan John can have at this stage. If he’s married and his heart is safe with his loving and committed wife, he’s free to be friends with Sherlock in the way that Sherlock appears to want. This is what you call having your cake and eating it, too.

Of course Sherlock didn’t mean to reject John with the Lazarus business. He wasn’t the biggest fan of it to start with, which is why he looked sad when John couldn’t see him, as we know. But Sherlock wasn’t emotionally mature enough to understand that John had chosen him above all others. He genuinely didn’t know that John loved him, as we see in series 3. He thought of himself as disposable, as, perhaps, merely the entertainment. What John interprets as a rejection is in fact just Sherlock’s immaturity, his low emotional intelligence, his attempt to behave entirely rationally rather than letting his feelings dictate his actions, and his strange and weirdly lopsided sense of self-esteem.

John thinks all along that his feelings for Sherlock are beyond obvious. But Sherlock has no idea how much John loves him. It’s what makes series 3, to me, so very interesting; it’s about Sherlock realization that he’s loved. But before Sherlock can explore what that’s like, how far John’s love for him goes, and whether he’s up to the task of reciprocating it like a grown up (he is! he is!), he’s got to contend with the fact that he’s ruined it already.

That doesn’t mean that John backs away. He can’t back away from Sherlock. In spite of how painful all this must have been, John swallows his pride and goes back into Sherlock’s orbit. That look on his face at the end of The Empty Hearse, when he looks at Sherlock like he’s the most beautiful thing on the planet: John is done for. He’s in love and there’s no shaking it.

It’s the most dangerous thing he’s ever done, allowing himself to fall back in with Sherlock again. But he won’t turn away. He won’t retreat. He puts up a million barriers between himself and Sherlock to protect himself as he does it (he can’t let Sherlock obviously be the centre of his universe again, not if Sherlock doesn’t want that), but he doesn’t retreat. He just finds a safer vantage point from which to lavish his love on Sherlock. Mary is the one holding his hand as he leans over that particular cliff. She’s his safety. (I doubt this would have worked in the long term, even if Mary was actually Mary Morstan as she claimed. But that’s a story for another time.)

Meanwhile Sherlock goes through an emotional puberty in series 3, leading him to do the opposite of what he did to John in The Reichenbach Fall; he behaves irrationally, out of love. He behaves truthfully, finally, much to John’s completely surprise. Series 3 is the story of Sherlock’s attempt to undo the damage he caused in The Reichenbach Fall, to make it up to John, to tell John that his heart is safe with him now, and from here on in, it always will be. Sherlock can’t say it in the end, but his actions say it as clearly as anything. But it’s too late by then, and he knows it.

It makes sense to me that Sherlock would be prepared to die in order to erase his rejection of John, because he owed John at least that much. It took him all of series 3 to figure out that John is the centre of his universe just as he is the centre of John’s, but articulating it with words it is one step beyond him, in the end.

Marrying Mary is John’s attempt to love and be loved in return. In relation to Sherlock, marrying Mary is meant to help John keep Sherlock in his life in a way that’s safer for all of them. I wouldn’t ever call that a retreat.