"It only takes a moment, but watching John's face go from near panic (Sherlock took a gun and is pointing it at the police, some of which are still our friends/ he's snapped and I can barely watch), relief (he's not pointing it at them anymore/ its pointed at me, I can deal with this), realization (oh, he's got a plan), and finally that face that looks like he's popping over to Tesco's for milk. ^^^^ This - this explains it all.
"So he's gonna put his trust in you now huh? 'Cause you dragged him out a burning building, wow, what a fucking hero you are. Bravo. Except you see, there's no such thing. Because nobody does anything unless they have something to gain by it. So you wanted what? His trust... his loyalty? Well, you got it Yuri. I'll be interested to find out what you plan on doing with it."- Balan
I love Molly. She’s so ordinary; and yet she’s not a shallow character. I love this moment because Sherlock has just been outdone by little Molly Hooper, and he just stands there, speechless. I think this is when he finally realizes that she IS his friend. And he looks guilty for not seeing her before, for not admitting to himself that she DOES count.