I didn't do anything...

In the following encounter, things were developing like they had in several of our previous games, and then...

Really, I didn't do anything.

 perrypawnpusher - Lark
blitz, FICS, 2011

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+

4...Kxf7 5.Nxe5+ Kf8

A couple of earlier conflicts continued 5...Nxe5 6.Qh5+ Ng6 (6...Kf8  perrypawnpusher - Lark, blitz FICS, 2009 [1-0, 30])  perrypawnpusher - Lark, blitz, FICS, 2009 (1-0, 59)

6.Nxc6 dxc6 7.d3

Or 7.0-0 (first seen in Jerome - Brownson, Iowa, USA, 1875, [1/2-1/2, 29] 7...Bd6 (7...Be6 8.Qf3+ Qf6 9.Qxf6+ Nxf6 as in perrypawnpusher - CorH, blitz, FICS, 2009 [0-1, 74]) 8.f4 g6 9.d4 Bd7 as in perrypawnpusher - Lark, blitz, FICS, 2009 (1-0, 18)

7...Qf6 8.0-0 Bd7

Or 8...Qg6 9.Kh1 Bg4 10.f3 Be6 11.f4 Bd7 as in perrypawnpusher - fortytwooz, blitz, FICS, 2010 (1-0, 29).

9.Be3

I really do not like making this kind of move. For starters, I much prefer lines where Black's dark-squared Bishop gets removed by the Queen, earlier – so that I can play f2-f4 as soon as possible. Also, here, if Bishops are exchanged, my broad pawn center gets compressed a bit.

On the other hand, 9.Be3 superficially looks like it un-defends the b2-square, making the pawn sitting there appear to be vulnerable to Black's Queen on f6...

9...Bxe3

Not such a good idea. The Bishop should retreat to e7 and retain Black's advantage.

10.fxe3

10...Qxf1+ 11.Qxf1+ Nf6 12.e5 Black resigned