A/N: this version of Sherlock and Mycroft's parents is based on my story "Sally Donovan, Freak-Wrangler" and not on the direction they actually went in the series, obviously. Just a little one-shot.

Mycroft Holmes, at age 15, worried about many things.

He worried that he would fail maths class. He worried that he would burst into tears in said maths class and all the other boys would laugh at him.

He worried that his mummy would die of the mysterious ailment that kept her in bed for days on end.

He worried that the British government would run out of money, because that would mean that his father would be out of a job.

He worried about the baggage retrieval system at Heathrow.

But mostly he worried that his father would kill his younger brother. The younger brother who, at this very moment, was sitting on the edge of the seat in the cab, feet dangling into space, determined expression on his small face, cradling his broken right arm with his left.

Mycroft leaned slightly toward his brother and contemplated that angelic little baby face. No wonder all his mother's friends cooed over Sherlock like butter wouldn't melt in his sweet little cupid's-bow mouth. He was adorable. That is, until he opened said mouth. Then all the ladies pulled back in horror.

Mycroft sighed. They were going to have to have this conversation, now, here in the cab. By the time they got to the hospital it would be too late.

"Sherlock," he began, keeping his voice low so as not to get the attention of the cabbie.

Sherlock turned his curly head just enough to glare at him.

"Sherlock," he repeated. "We need to talk about what to say to the doctors."

"What do you mean?"

"About how you broke your arm. We have to think of what to tell the doctors."

"I'll tell 'em Father twisted it up behind my—"

"Shhh!" Mycroft shot a frightened glance at the cabbie, but the man was still staring straight ahead. "No, Sherlock, we can't tell them that."

"Why not?" the smaller boy shot back. "It's the truth. You said always tell the truth."

Mycroft gritted his teeth in frustration, a frustration borne of terror. Because at some point, probably very soon if he were to realize his ambitions, he would have to go away to school and leave his baby brother to face the monster alone, and the only way the little shit would survive was for him to learn now what to say and do to stay alive.

"We tell the truth when we can. But sometimes it is more useful to be able to make up a convincing-sounding lie."

"Why?"

"If you tell them that Father broke your arm, what will happen?"

"The coppers will come and take him off to jail," Sherlock rejoined with a savage expression twisting up that adorable little face.

"No, they won't."

"They won't?" Now those little lips tilted downward into a frown.

"No. What will happen is that Father will be angry. And what happens when Father is angry?"

"I get hurt," Sherlock said reluctantly. His eyes traveled downward to his arm cradled in his lap.

"That's right. So a lie is useful to avoid that consequence. We'll tell them you fell out of a tree."

"Which tree?"

"The Maple tree in the front yard."

"What does a Maple tree look like?"

"It's got big leaves, like a hand."

"This big?" Sherlock turned his small left hand over and stretched out his skinny fingers.

"No, bigger."

"How big? Exactly?"

"I dunno. As big as my hands, I guess."

"And how far did I fall? Was I really high up?"

Mycroft pinched the bridge of his nose. "I don't know. High enough."

"Pretty high, I think. I'd have to be pretty high up to break my arm. I'll tell 'em I was halfway to the moon."

"The moon? This happened during the daytime."

"No, I'll say it happened at night. And werewolves were chasing me. But I'm a pirate so I fought 'em off with my sword—" He made a slashing movement with his good arm and almost fell off the seat.

"No, Sherlock, you can't say that!" Mycroft hissed under his breath.

"Why not? If it's a lie, it might as well be interesting."

"No! It was daytime, you were climbing the tree and fell out. I'm bringing you to hospital because Daddy was away and Mummy is sick."

Sherlock leaned back against the seat. "That's boring," he grumbled under his breath. "You take the fun out of everything."

And so Mycroft Holmes worried. Because how was the boy to survive if he was more concerned about things being "interesting" than he was about keeping himself safe? It was up to Mycroft to protect him, and the burden rested heavily on his young shoulders.