A/N: Just the same as ever: I own nothing recognizable from Sherlock BBC. Oh, this is Sherlock/OFC. Ha!
"Do you want to kiss me?"
Katharine was the younger sister of one of Mycroft's friends, who, really, Sherlock knew, was only friends with Mycroft because his mother was friends with Mummy. Mycroft couldn't stand the boy, but unlike Sherlock, he had the diplomacy not to show it. Sherlock was eleven and Katharine, crouching down to poke at a toad that was sunning itself on one of the flat slate squares leading to the fountain, was nine. She followed him around and passed him his microscope when he held out his hand. She caught small amphibians and held them still so he could collect on Q-tips the moisture they secreted to help them breathe. She pulled the wings off of dragonflies – she didn't mind dragonflies, which was strange, for a girl – to look at them under a microscope.
"Why?"
Katharine brushed the hair out of her eyes and stood up. She was sweaty in the summer sun and plucked absently at the collar of her shirt. There were grass stains on the white knees of her stockings, and dirt under her fingernails and smudged on her nose. She smiled at him brightly. He blinked; looked from her nose to her mouth.
"Dunno. Henry's always talking about all the girls he's kissed."
Sherlock wondered if Mycroft had ever kissed a girl.
"Okay."