Oh my God, I loved this! Favorite lines:

When Watson asks, Holmes says, "The invention of mustard gas has persuaded me that the great days of chemistry are over."

and

He keeps them in a jar on the bedroom windowsill, and every time he sees them he remembers that time and nature wear away all the sharp edges of manmade things.

And wow, the bit where Watson comes to Holmes' bed. *flails* This whole thing was beautiful.