Who Sherlock and John actually are 

(Sherlock Meta by Pretty Arbitrary)

I think that Sherlock is probably either asexual or demisexual, and that it’s very rare for him to feel a compelling attraction (whether sexual or emotional) towards anyone. And when he does, his arousal (whether sexual or emotional) tends to be generated primarily from his intellectual fascination and engagement with them.

(So far, that’s not really headcanon, is it?  That’s just what the show has given us.)

Furthermore, I find it interesting, the sorts of people Sherlock seems to tend to find attractive (for a given value of ‘attractive’).  I don’t know whether he acted on it, and I don’t know how extensive it was, but I think that he found Irene and, yes, Moriarty both attractive in this sense.  (And I think that Moriarty crushed whatever burgeoning fascination Sherlock was developing when Sherlock discovered that he wasn’t just weird and different and brilliant and interesting, but that he was also evil.  Irene’s brand of manipulative but not murderous amorality, he seemed to find more acceptable.)

I wonder if Sherlock finds people like them appealing because they are fascinating and brilliant and challenging and different, or if he finds them appealing because he has enough narcissistic self-obsession rattling around inside him that he is automatically drawn to people who remind him of him.  (Both of them are characterized as being both physical and intellectually parallel to him; Moriarty with his suits and his similar view on the world, and Irene with her eyes and cheekbones and hair and…everything.)  And I find the possibility of that interesting, because is this Sherlock being fascinated by his own damage/weirdness, when he believes he sees the same thing reflected back at him from others?

Whatever is going on there, I think even Janine fired it up in him, a little bit.  I think he was definitely pretending when it came to an actual relationship with her, but she too is weird and interesting and different and a bit ruthless, and he liked that in her (and she liked that in him).  It might even include Mary, just a little (“I like him” she says, and Sherlock rather likes her).

And usually the people who find Sherlock truly compelling and attractive are the people like these, who hold up a mirror to his own weird different challenging ruthless brilliance.  And I think that Sherlock is at the same time attracted to and repulsed by the ruthless brilliant different people, because they are not good (and, he believes rightly or wrongly, neither is he).  While they’re fascinating, he was raised in a home loving and nurturing and rational enough that he understands that in the end, he does not want that for himself.  It is not the kind of love that you cup in your hands and hold close to your heart for its warmth and light on a dark night.  It does not nurture.  It cannot truly and wholly love you back.

But then, there is John.  Sherlock finds John appealing partly because, despite all John’s camouflage, he too is weird and different, and he can be ruthless and challenging, and maybe he’s not brilliant but he makes Sherlock more brilliant and that’s even better.  But also I think—even more deeply and more truly—he’s attracted to John because alone of all the people who have compelled and been compelled by Sherlock, John is the only one who is actually a really decent human being.

John’s not perfect.  He has some real doozy moments.  But fundamentally John is somebody you could reasonably trust to do the right thing by other human beings in the area.  John is somebody who will care about you, and take care of you, and be reliable and devoted to you.  He nurtures, and he loves with a glowing warmth that radiates from every fiber of his being.

And I think this appeals not only to Sherlock, but also to Mary.  (And maybe it is also the reason why the true monsters always give him a second look too—because for them, someone who is both different and challenging but also still good is something interesting and different enough to at least be worth a moment of attention.)

And as for John, I think that John is probably primarily (but only? we have no idea) sexually attracted to women, but that he forms very deep and powerful emotional (maybe even romantic) bonds with certain men.

(Again, when it comes to John, so far this is just what we’ve seen for ourselves.)

We’ve seen that he likes men who are commanding, unsociable, and difficult.  I think he likes being needed by them.  I think he likes being challenged and pushed and even frightened by them.  They are men whom (I assume, given John’s level of fondness for his old commanding officer) he trusts with absolute and unshakable conviction—men whom John is not only willing to entrust with his entire being, but who will actually ask him to put himself into their hands (again, this is the nature of a commanding officer in a warzone, which is what both Afghanistan and, if you believe Mycroft, London are).

They are also both men who recognize, appreciate, and respond to John’s total faith in them.  Both the men we have seen (and the woman, as it turns out) are people who put him in danger—but also they are also people who share the danger with him.  They may be his commanding officers, but he expects to be treated as a full partner, with his own role and responsibilities.

Furthermore, John clearly needs this.  He was a ghost of a man at the beginning of the series, and all indications are that when he thought he had lost Sherlock, he grieved with all the ferocity of a besotted widower.  Possibly (although the flat was nicer) he even returned to that half-existence he’d lived in before he met Sherlock (and we can wonder, now, whether that malaise before ASiP was due to his being kicked out of the war or due to the ‘loss’ of his commanding officer?).

So this relationship he has with these men, sexual or asexual, romantic or otherwise, is clearly deeply-rooted and intense, something that fulfills a long-standing need in him at least as deep as his desire for a spouse.

And I think that Sherlock and John absolutely are in a committed long-term emotional relationship, whether romantic or otherwise.  I don’t know how consciously aware of this Sherlock and John are (sometimes they seem more aware of it than others; did Sherlock consciously think of his vow as a wedding vow?  Did John consciously realize what was coming out of his mouth in the confrontation at Baker Street?  How aware were they of…hell, everything during John’s stag night?), but I think that Mary is aware that having John inevitably means sharing him with his other life partner.

As Sherlock recognizes that he must accept it.  There may have been a time when he could have kept John all to himself, but he abrogated any right he had to that when he left for two years and told John nothing.

So, finally, what is it that makes John take Sherlock back?  What is it that makes him take Mary back?  What happens in those episodes that we don’t see that somehow makes up for what they did to him?

Nothing.  Nothing makes it okay.  There is nothing that could possibly make lies and betrayals of that magnitude okay.  He is John, and he loves them, (and maybe taking the calculated risk that his loved ones won’t do such a thing to him again is even a bit enticing to him—after all, Doctor Watson always had a gambling problem, but this Watson plays for higher stakes than horses), so he gave them a second chance.

And, finally, how could he give Sherlock such a cold send-off?  How could he stand so stoically, watching Sherlock fly away?  Because

1: Like I said before, they are both emotional turtles and I’m pretty sure they would both rather be shot again than be caught blubbering with sentiment.  And

2: Because Sherlock might think they’ll never see each other again, and Mycroft might think they’ll never see each other again…but Sherlock promised John he’d be there for a lifetime.  And John has learned that when he bets on Sherlock, he always, always, always wins.

And that is who I actually think these men on the show are.