Sherlock had tried his best to keep Mycroft from knowing about the bridge between worlds. But his brother saw everything, knew everything, and Sherlock's prolonged absences did not go unnoticed. At first he'd only visit for a few days, but the world sucked him in and soon he was gone for weeks, months at a time. When he returned to his own world, emerging from behind a crop of bushes in a London park, a black car waited for him on the street. He sighed in defeat.

"You wouldn't like it there." Sherlock sat in one of Mycroft's large armchairs, arms crossed, a distinct poutiness in his voice that reminded his brother so much of childhood. A long evening of explanations, supplemented with the surprisingly vast store of knowledge Mycroft already had on the subject, had resulted in this stalemate: Mycroft wanted to visit Sherlock's secret world. And the younger Holmes would do anything he possibly could to prevent that from happening.

"You would be bored."

"It seems to be entertaining you well enough. No easy feat…"

"You wouldn't be in charge there, you'd be nobody. I know how you loathe being overlooked."

"I think I could manage." Mycroft smiled.

"It's a rather small hole to get there, you probably won't fit," Sherlock sniffed.

"Sherlock." Mycroft's voice was a harsh blend of aggravation and finality.

The next morning there were two Holmes in the mirror London, oddities to say the least. Both missing something important. But a week later a large horny owl swooped onto Mycroft's shoulder and never left.

Eight years later Sherlock still kept the windows open at night.