Ah ah, yeah, the military kink is what came to my mind! Plus all that happens to be related to John interests him, so I really do believe he made a great deal of knowing this kind of facts.
Yes, yes yes, it reminds me a thing I wrote about the “there is nothing new under the sun” thing (here), where I said that for what we see John’s story is repeating itself, “there is nothing new under the sun”, what we saw here happened twice, once with Sholto and the trauma from war + come back to civilian life and the second with Sherlock and his death, with some changes, twice he lost everything that mattered to him - and it nearly happened a third time.
The second is such an echo of the first, it can help us understand what happened to John before he met Sherlock, btw, I think that’s done on purpose for us to recollect the pieces to understand John’s story.
That’s not to be forgotten, and it makes the pain twice as intense. x) But the good thing is that things are going to change for John, the story wont repeat itself endlessly.
Once we saw all of this (and with some of the other bits about John’s grieving that we didn’t talked about in this thread), we can see as clearly as possible how John was feeling there, he may look “normally” sad given the circumstances but it’s obvious right there he is broken deep down, and Sherlock undoubtedly understood it (at least partly).
I remember I said before that Sherlock must have realised in this moment that John actually cared about him. (that was in an old post here, that was my first meta, so to speak :3 ) When he says later “I never knew you cared”, in the bombed train, he is absolutely serious, he just covered it with sarcasm, that’s his way to conceal his feelings, he uses jokes and sarcasm, but it’s to be taken seriously.
When he chose to disappear, he believed John would go through it without much damage, but at the graveyard he saw John’s pain, even more clearly than at the rooftop, and he understood how he misjudged John’s affection for him, he realised he made a mistake, that he hurt John more deeply than he thought. In the train he isn’t just saying “before this exact instant I didn’t knew you cared”, but “when I left, back then, I didn’t knew. But now I do.”
So in this scene, John is incredibly in pain, and Sherlock realises he is indulging it. And, I also talked about it here, that’s probably why he lets John beat him in TEH at the restaurant without even trying to defend himself, the guilt he feels may be as massive as John’s pain.
So, to recap: John is broken, damaged, in pain, in this scene, and Sherlock can see it, he sees it and believe it is his fault - as least as much as he knows it is Moriarty’s fault. Both are so hurt, it makes trf and the post-reichenbach so deeply painful to see. No, indeed that’s not the fall that kills you but the landing, the realisation of the fall’s consequences.