That seemingly offhand remark speaks so much of John’s insecurities and doubts about his own self-worth, now that he is (at least in his mind) rendered useless after he’s been shot. As we flash back to this very first remark, we now understand that John has truly meant what he has said to Sherlock’s grave: “I was so alone, and I owe you so much.”
The remarkable and extraordinary thing about John Watson is that… he knows he’s ordinary, but he doesn’t realize how he possesses such delicate, intricate, beautiful poetry in the simplicity of his being. I will not attempt him to make him into more than what he is; despite being an army doctor, he is still somewhat average compared to the forces of nature around him (the Holmes brothers, the consulting criminal, The Woman.) But he carries within him a subtlety and warmth and strength and danger that is all the more curious and interesting and fascinating because of his gentle restraint and tremendous control.
And that’s why a man like Sherlock Holmes wanted him for a flatmate. Sure, John Watson is ordinary. But as a conductor of light… he is unbeatable. Because the extraordinary thing about him is… John Watson doesn’t live for himself. He lives for other people. His purpose in life is to save them.
And deep down, perhaps Sherlock knew that he needed a sort of saving as well. He needed someone to save him from himself.
And perhaps he knew, that fateful day in Bart’s, with an instinct that even his logic and deductions can’t hope to explain… that this washed up war hero is the perfect candidate to save the one and only brilliant consulting detective in the world.
So yes, John Watson. Sherlock Holmes wants you. And maybe, it’s true that no one else will want you. But that’s only because only an extraordinary man like Sherlock Holmes sees what is invisible to every one else’s eyes.
… He sees you, John. :)