"In an instant he had whisked out a revolver from his breast and fired two shots. I felt a sudden hot sear as if a red-hot iron had been pressed to my thigh."
-- Conan Doyle putting the pain to Watson
A lot of Sherlockians really enjoy seeing Watson get shot in "Three Garridebs."
You know why -- it's not the cry of pain that Watson doesn't put into his account, it's Sherlock Holmes's show of concern for his friend. (It's kind of a stupid show of concern, if you really think about it, as Holmes goes "For God's sake, say that you are not hurt!" and Watson's truest reply should be "Dammit, Holmes, he shot me! It hurts like a $#%@%!") From an author/character point of view, Conan Doyle had Watson take a flesh wound just to show Holmes's reaction and give the readers a little treat. It's what writers do, abuse their characters for our pleasure.
It's one thing when a character's creator does it, but what about when a fan does it?
If you are a great fan of John Watson and you love the character dearly, how much pain are you willing to put him through to give yourself and your friends a jolly time in your writing and their reading?
Ever since I first read Star Trek fan fic in the eighties, I've been aware of fan writers doing damage to their characters to get an emotional result. There was actually a known sub-genre of Trek slash fiction called "hurt/comfort" that involved damaging a character so another character could get emotional in caring for them. Mr. Spock, being a lot like Sherlock Holmes, required some prodding -- and sometimes painful-to-someone-else prodding, and some horrible future-tech sort of damage prodding at that.
With Sherlock Holmes and Dr. Watson, I've always had a real problem with putting the pain to the boys. I like them too much. I can fall into denial about the level of Holmes's drug problems very easily, and have never really liked Meyer's revisionist text (which also steals a true Moriarty from us). Watson can have marital troubles, a few hallucinations from pre-existing trauma, sure -- I've done both in my writings. But he's never suffering too much from either, having Holmes as his happy place in both situations.
It's an interesting alchemical formula, this mix of how much one loves a character versus how much pain one will put them through to see them behave in a way one wants them to. The black market of fan fiction has always dealt in the "Let's see what we weren't shown!" of things. And if Sherlock Holmes and Dr. Watson never did anything but what happened in the sixty original stories, that's fine with me, because those stories offer enough headcanon that, like Steve Rogers, "I can do this all day" just elaborating on what's there. Horrible hansom cab accidents or Moriarty-run torture scenarios aren't in my wheelhouse.
For some folks, however, they are a fair price to exchange for an intensity of emotion, enhancing our friends to a new level of excitement. It would be good fun to run some elaborate study of Sherlockians with a barrage of questions, generating some numbers to correlate, generate, blah-blah-blah-cate, and all that data analysis stuff to see how we work as a culture. Some interesting questions there, I think.
How bad can you hurt them for a story? Or would you rather keep them in a bullet-proof glass case of Canon, safe from all harm? And how do we fall on that spectrum with Holmes and Watson from "Gruesome Slow Murder" to "Impervious Immortals?" There's an interesting curve there to be sure.