Two days earlier.

"Of course, you're not really a woman."

Sherlock was in declamatory mood, sprawled in the tatty armchair with an apple in one hand and the other draped over the side, fingers curled with the easy grace of a ballerina's pose.

He took a bite of the apple and appeared amused by Joan's irritation.

She had been reading a paperback in the equally worn chair opposite. Now she looked across at him, scowling. "I'm not a woman."

"Correct. In this context you are many things, but gender is irrelevant." Another passive aggressive crunch of the apple. A glint in his sharp blue eyes.

She studied him. She knew better than to rise to it, but she couldn't help herself. "Ok, why?"

"Consider the situation, Watson. A man and woman sharing a flat with no familial, fraternal or sexual relationship. It's almost impossible."

"It's a professional arrangement," she reminded him.

"Yes, but this is your evening off." He threw and caught the apple one handed and took another bite. "Yet here you are, spending time in close proximity to a person of the opposite gender, without a flicker of difference to your on-duty demeanour. You have no female friends and no boyfriend or sex buddy."

Joan raised her eyebrows. "Excuse me-?"

"Therefore in this context you are androgynous, removed from the social sphere, to all effects genderless."

"Like you," she pointed out.

"Yes, exactly. Gender based social expectations are limiting and demeaning." He held her gaze and ate the remainder of the apple, core, seeds and all. Then he flung himself back in the seat, his long legs sprawling towards Joan's chair.

"Right. So my lack of gender is a compliment?"

He looked surprised. "Yes, of course."

Unbelievable."Think I'll take my gender freedom somewhere else."

She pursed her lips and held up the book. Sherlock peered at the title as she swept past and up the stairs.

'How to Deal with Difficult People.'