Or, "Every argument between Sherlock and John, ever."
Step 1: In a fit of excitement (or maybe a fit of depression), Sherlock fails to respect John's personal space/feelings.
Step 2: John finally gets fed up and he and Sherlock have a little fight and then sulk at one another for a while.
Step 3: Sherlock betrays his cold, calculating exterior, revealing in some small way that he has a heart. John forgives him, because John is charming that way.
I'm planning future installments of these, for anyone who cares.