What’s amazing is they had Benedict for Sherlock before they figured out a Watson, and they had him read with other actors but nothing worked until Martin Freeman showed up. They said it was like magic, the chemistry immediate. They stopped looking – they found exactly what they were looking for. Benedict became a better actor, “he raised my game”. Mark Gatiss said “That’s it, that’s the show”. But that should be taken literally, not just figuratively.
This is EXACTLY the story to Sherlock. The detective was bumbling about looking for someone to complement him, for someone to raise his game. He meets John Watson and slowly lets himself love. He becomes a better person. A good man. Simply because of the immediate chemistry between Sherlock and John.
I wonder why Faith’s cane reminded Sherlock of John from that particular scene. In A Study in Pink, Sherlock had taken off earlier and left John alone there, so he couldn’t see how John had walked down the road leaning on his cane at that time.