A really nice vignette of why John is so integral in Sherlock's life. Even though the good Doctor would be the last to hail himself as anything special, he really is the only one in Sherlock's life that cultivates a healthy appreciation for his skills. It's a level of kinship that goes beyond just being "buddies".
I like how you captured Sherlock's logical (and yet so skewed) measured thought, and the importance of John within them. Lovely.