John was always careful to knock when he needed into Astrid's room. It wouldn't do to walk in on her changing or something; she wasn't actually his child. Sherlock, however, never remembered things like that, which is why one day, he got a high-heeled shoe thrown at him.
He burst in, just as Astrid was peeling off her last layer. She shrieked and he just stood there, completely unbothered.
"Oh, come off it. One, I'm your father. Two, I'm not interested in women, especially not those in the throes of puberty. Third, I've seen more naked bodies than I care to enumerate at the moment, because I need help. Explain to me in great detail the plot of the fifth Harry Potter book. I believe I have a serial killer using it to plan his murders."
The strangely shoe-shaped bruise lingered for a little over a week.