A.K.A The Heater

We know that Sherlock went to the roof meeting with Moriarty with the intention – or, at least, the contingency plan – of faking his death.  But how much did he know?  And what of the multiple usage of “I.O.U.”?  After untold viewings of the Series 2 finale, here’s a possible explanation.

Sherlock went to the roof fully prepared to “die.”  And he knew, from previous experience, that Moriarty would not hesitate to threaten those he cares about to make Sherlock “dance.”  He doesn’t seem very surprised, then, when Moriarty does threaten his friends.  He even knows the exact three people that Moriarty planned on using.  Now, is this because these are the only people close enough to Sherlock that can be used for his manipulation… or is it because Sherlock has observed, and knows, who is going to be threatened?  This is where the I.O.U.s come in.  Moriarty says he “owes [Sherlock] a fall. I.O.U.”  Does Sherlock think this is a fall from grace, or a literal fall?  That’s another discussion (although they both did become a reality).  But then there’s the apple in 221B into which Moriarty carves I.O.U.  Then there’s the I.O.U. in the windows across from Lestrade’s office.  And then there’s the final I.O.U., in the form of graffiti on a building on Baker Street.  Are these I.O.U.s marking Moriarty’s potential victims?  The apple in 221B (Mrs. Hudson, the landlady of the apartment building), the office windows visible from the DI’s office (Lestrade), and the graffiti (John, who did get that ASBO in “The Blind Banker” after taking that fall).  So if Sherlock knew that John, Lestrade, and Mrs. Hudson were marked for death, he was only confirming his suspicions that there were, in fact, only “three bullets” and “three gunmen” for John, Lestrade, and Mrs. Hudson.  In which case he also suspected that Molly was not marked, which is why she was safe to seek out for help, and why he had to put distance between himself and the other three.  Maybe?  Or perhaps I.O.U. another explanation…