When his housekeeper introduced your brother, Sherlock looked up from his book with a smile, and opened his mouth to greet his old friend. Then he spotted you behind him, and quickly rose to his feet.

He blinked several times. “I’m sorry,” he said.

“Sherlock,” your brother repeated, “May I introduce, my sister.”

You stepped out from behind your brother, eyes lowered, shy and unsure. Sherlock walked slowly towards you, and a feeling grew in his gut that he was not altogether familiar with. You raised your eyes, and his steps faltered while his heart began a rapid tattoo that he could feel all through his body, most noticeably in the thickening length between his legs.