A 221B. Thanks once again to I'm Nova for the encouragement!

"Mycroft?" Sherlock tugged on his older brother's sleeve, short legs stumbling in their attempt to keep up. "Mycroft!"

Mycroft stopped with a long suffering sigh. "Yes, Sherlock?"

Wide grey eyes looked up at him earnestly. "Will you play with me?"

"No." Mycroft shook off his younger brother and kept walking. Sherlock ran after him, quickly losing ground against Mycroft's much longer stride. "Mycroft! Please? Mummy's busy, and nanny's in the kitchen talking to cook, and I need someone else to play with!"

Mycroft slowed, but didn't stop. "Why can't you just play by yourself?"

"It's no fun playing by myself. I want to play with you!" Sherlock finally got in front of his brother, standing directly in Mycroft's path with his arms crossed, stopping Mycroft from going any further.

Mycroft stopped in front of him and crossed his arms, a near perfect reflection of the younger, even down to their stubborn scowls. "I'm too old to play with you, Sherlock. I'm twelve now. That's practically grown up."

"Mummy plays with me, and she's grown up," Sherlock countered.

Their gazes locked. Stalemate. Mycroft looked away first. "I'm not going to play with you, Sherlock. You'll have to find someone else."

"But there is no one else!" He came closer, tugging again on Mycroft's jacket. "Please?"

"Alright, fine!" Anything for his baby brother.