The border between a good man and a great man is more than that of a single word, and the gulf is wide.

There are many men who are good. It seems a very simple thing, to be good.

Lestrade is good. For all he's a dense wanker at times, Sherlock recognizes that Lestrade is, in fact, good. Even if he weren't as surrounded by the exceedingly dull and blind as he was throwing him into (relatively) high relief, Sherlock would know this.

On some level, it is that goodness, for all it's wrapped in surliness, that enables Sherlock to work with Lestrade, and Lestrade to work with him. For Lestrade, he cares more about saving people's lives and bringing the "bad guy" (how tedious) to justice. That caring lot. But since Lestrade tossed his lot in with that, it means he places more importance on the results than on his own pride, or letting Sherlock overly get under his skin (conditional, this. The fake drugs busts being pulled out for when Sherlock has pushed him too far.)

For Sherlock...he is self-aware enough to know it's not just that he works with Lestrade because Lestrade lets him into crime scenes. If it were only that, he knows, he would hold Lestrade in as much contempt as the gaggle of fools the Met employed. No...even Sherlock recognizes, for all he is loathe to admit it, that good, illogical and superfluous though it is, is something that draws him because he has so little of it.

It, in many way, explains both Mrs Hudson (though she is a good woman, not a man, but that is a negligible point), and John Watson, who is, quite simply, the most good of all the good men Sherlock has ever met, and it was that spark of goodness he saw in John's easy smile and the way John handed over his cell phone the first five minutes they met that told Sherlock John would be a good fit for him.

Opposites, and all that.

Sherlock was not a good man. He, like Mycroft, was one of the rarer ones. He was a great man.

He and Mycroft both being great men was why they did not get on.

Great men were capable of things the boring, tedious masses were completely incapable of. They were different. Separate. None of that ridiculous caring lot that got in the way of accomplishing.

Sherlock knew he would never be a good man, which was why he surrounded himself with them. It left him free to be great, without having to heed any of the boring niceties of feelings or caring that good men felt - the good men smoothed the way for the great ones.

That was how it was.

That was how it should be.

Or so Sherlock thought.

Or so he thought until Moriarty strapped one of his good men, the best of the good men, with explosives, and he began to doubt - doubts he pushed away as just adrenaline. John was fine, no harm done, and now there was a great man to match wits with in the greatest challenge of his life. None of that caring lot. And John was fine.

Silly doubts were pushed aside for the chase, the chase given more urgency than normal because Moriarty knew, somehow, that Sherlock...that he needed these good men, almost as much as he needed a challenge.

The doubts faded, until Sherlock learned that Moriarty did in fact know all of Sherlock's weaknesses, and Sherlock had to make a choice: continue to be a great man, or become only a good one.

And on that roof, with the snipers pointing their bullets at Mrs Hudson and Lestrade and at John, when his own greatness was thwarted by Moriarty's, that Sherlock makes his choice.

The border between a good man and a great one is more than that of a single word, and the gulf is only that of the mere inches between standing on a roof and going over it.

And when he made that choice, when he cut himself off from all the good people in his life to save them, for the first time in his life, Sherlock becomes one.