(Sherlock invites himself to the crime scene where Bell claims to not need help.)
Sherlock: Actually you wrote, and I quote, "Yes Please, now. Triple smiley face with tongues protruding" (Sherlock hands Bell his phone.)
Bell: Yeah, see that's not from me. That's from somebody named Bella. You got it last December. My name is Bell, no a. I can see how you might confuse us though, it's not like you're into details or anything. (Bell passes the phone back to Sherlock, who puts it away.)
Sherlock: How embarrassing. Anyway, now that I'm here.
(Detective Bell thinks out loud and is on the right track while Sherlock sniffs the walls.)
Sherlock: Have you always been this observant? (Silence from Bell.) I'm asking that quite sincerely. I was wondering if exposure to my methods have helped you in any way.
Bell: Actually, before you came along, I'd never closed a case before. (Sherlock goes back to working.) Neither had the rest of the department. Most of us were thinking about packing up, leaving and letting the city fend for itself.
(Watson and Sherlock talk in the brownstone.)
Sherlock: I'm an expert on poisons Watson. I know virtually everything there is to know about them. But I've come to learn over the last few years is that there is nothing on this planet quite as toxic as guilt.