Tâmm

So John tires easily. Sherlock isn't aware, perceptive as he is, of the true nature of John's weakness. He drags John along to every case. John is afraid to let him down and follows without complaint, but each case ends with him feeling worse and weaker.

He falls truly ill one day. Too worn to even rise from bed and burning hot with fever. It feels like he's back in Afghanistan, like he's in the war again, like he's dying in a foreign country and there's nothing he can do to stop it--

If it weren't for Sherlock, petting his hair and sponging his sweat-sheened brow and murmuring,

"I'm sorry. I didn't know. I'm so sorry, my dear Watson."

In the same episode, Holmes introduces Watson in front of others as:

But when it’s just the two of them, he chooses completely different approach and words:

The contrast, the formal politeness in public vs. the very deeply affectionate words in private.

I visited Reichenbach falls recently and was taken by how accurate this illustration by Sidney Paget is (the waterfall itself is significantly diminished in strength because of a hydroelectric dam upstream).

Also, if anyone is curious what Holmes and Moriarty might have seen while they were falling, here is the view backwards from the same spot, overlooking the town of Meiringen:

Also, Watson was not kidding when he wrote this in the Final Problem:

"In a tingle of fear I was already running down the village street, and making for the path which I had so lately descended. It had taken me an hour to come down. For all my efforts two more had passed before I found myself at the fall of Reichenbach once more."

from Meiringen to the falls,

and fairly steep too.

No one at Scotland Yard is put off by Sherlock Holmes. Sure, they all know he's a little weird, but in their field who's not a bit strange? And he's damn good at what he does too, and he's really very nice when you get to know him.

You know who they are terrified of? Watson.

Because Holmes had found himself a flatmate, and everyone was prepared for the certain level of strangeness that must accompany anyone rooming with one Sherlock Holmes. But Watson is deceptively ordinary, and that's where the fear starts.

Because this man is a civilian, a doctor, he wears knit jumpers for god's sake, and he should be the everyman presence at the Yard. But any officer can tell you that Watson is the one you need to watch out for, because Watson will shoot a man at point blank range for looking at Holmes wrong, and then have a cup of tea about it afterwards and look at you like you're the crazy one. Watson once tackled a serial killer for no reason other than the fact that he could and no one had told him not to. Watson, early on in his whatever-he-has with Holmes, had arrived at an absolutely gruesome double murder and not batted an eye.