LF Specific Finger Rating System - BBC Sherlock

[paintedame.livejournal.com]

All I'm sure about is that it was John/Sherlock in BBC 'verse. That John was using fingers in a locked room (changing the number of fingers and details, right indexes, painted pink, oriented to the compass points, etc.) as an analogy for how interesting/good sex is for him. They end up making a rating system using the fingers for each 'encounter'.
Not quite sure, but I think it's in there: first time. Might have started with Sherlock asking why John goes to such lengths (finding girlfriends, etc) to have sex. Could have been virgin!Sherlock but I don't think so.
Next, I feel stupid for loosing this story so it must be something obvious.

Any help would be greatly appreciated, thank you in advance.

PaintedAme

FOUND!: It was Planet Sherlock by Pir8fancier.