There is a Door in Sherlock's Mind Palace that remains locked with a heavy brass Key, a Key whose bow curls into nightmarish rococo designs too complex for a normal person to follow.

This disgustingly poetic image may well be the least repulsive aspect of the whole affair.

For example, Sherlock knows how loofah ages, how it softens with time, moisture, and a touch of mildew. He knows what human skin looks like after being scrubbed for various time periods using loofah of every possible degree of abrasiveness.

Give Sherlock a dead man in a shower and he can tell you exactly how long the man scoured his body to rid himself of the memory of killing his sister before succumbing to the poison in his shampoo.

This means that Sherlock could also tell you exactly how The Woman's left shoulder would look as she washed Pakistani dust from her collarbone.

He unlocks the Door and darts the thought inside like a burning paper aeroplane.

Sherlock knows nearly everything. He knows how it would feel to slide his fingers over the diamonds around her neck, to guess which member of Parliament gave them to her. He does not need to imagine how it would feel to fight a quaint desire to replace everything someone else gave her with exact replicas touched by no one but him.

She isn't dull.

Her intelligence and their similarity precludes the possibility of him deleting her.

He slams The Door and chokes down The Key like choking down food.