Title: The Detective (With The Brain of a Scientist)

Author: starjenni

Disclaimer: Don't own anyone.

Pairings: Sherlock/Mycroft brotherly angst, mentions of Sherlock/John friendship.

Warnings: angst, serious Mycroft feels.

Rating: T

Spoilers: For both series, all episodes.

Word Count: ~1100 words

Summary: Mycroft Holmes does not understand his little brother.

"My brother has the brain of a scientist or a philosopher, yet he elects to be a detective. What might we deduce about his heart?"

"I don't know."

"Neither do I."

Mycroft Holmes does not understand his little brother.

He cannot predict him, he cannot see what Sherlock will do next, he does not know him at all, he does not and never has understood the workings of Sherlock's mind.

It is a common misconception that he does, because he and Sherlock have the same observant nature, the same powers of deduction. His parents thought he did. Even John Watson, to some extent, thinks he does, and he is closer to Sherlock than anyone. But Mycroft does not.

Sherlock, to his older brother, is entirely alien. He is, in fact, more alien to Mycroft than anyone else in the world. Mycroft can read people like very dull, overrated books, but he cannot read Sherlock. Or rather, he can, he can look at the creases in Sherlock's trousers and deduce one thing, and then he can keep deducing, he can make several deductions all as good as one another, and yet in the end not have a clue which of them is true. Because it is Sherlock, and Sherlock is as always as distant as the moon to him.

Sherlock will refuse to feel and yet sometimes feel more deeply than any person alive. Sherlock could die of lethargy or die in action. Sherlock says that normal people are boring and yet has formed the closest bond Mycroft has ever seen with one of the most normal men in the world.

Other people are predictable in their movements, in their motives. Sherlock changes at a whim, and Mycroft can never keep up.

Irene Adler. Mycroft never did work out what happened with her. He couldn't decide, when they found her in the morgue, whether Sherlock was devastated or didn't give a damn. He took the cigarette, yes, but what does that prove really? Nothing, Mycroft Holmes, you know that.

John Watson. Is it love or the deepest of manipulations? What would Sherlock do if John died? Mycroft cannot answer the question. He has thought about it over and over and yet he does not know. He does not know.

Other people can be mysterious, certainly. But Sherlock is veiled in mystery upon mystery.

The first time he realised this, he was 21 and Sherlock was 14. It took Mycroft 21 years to realise he did not know his little brother at all.

Mycroft was home from university for the summer, and the family were discussing Sherlock's career options over dinner. Mycroft had always assumed that Sherlock would be a scientist and was only undecided on what form of science he would choose to pursue. But that Sherlock would be a scientist was a given. He was a genius and he was eccentric. He blew up the lab at home on an almost weekly basis. He paid attention to the tiniest of details. He was practical and methodical in all of his thinking.

Their mother had decided Sherlock would be a philosopher. She was the closer of the two of them, in the end.

"I'm going to be a detective," Sherlock had announced confidently over dessert, and then proceeded to outline the career of a 'consulting detective' and what that really meant.

Mycroft had sat in silence for the rest of the meal, entirely nonplussed. He had not seen it. He had not even suspected it. And yet it all made sense. Sherlock paid attention to the tiniest of details, but also the strangest. Sherlock studied people almost as clinically as Mycroft did, but not exactly. In their little deductive sessions, he would always visibly relish the more emotional tells people broadcast than the cold, hard facts on which Mycroft always based his deductions. Sherlock loved the drama of people. Sherlock loved the complexity of life. Sherlock loved the colour.

Detective, Mycroft thinks now, is not all that far from pirate really. It all involves drama, and excitement, and the stories of ordinary people. He should have listened to the five year old Sherlock and realised it then. But then Sherlock confuses him more than anyone else ever has, or ever will.

Sometimes he thinks that he is too close and therefore he cannot see as others do. It is like trying to look at the sun when you're standing right in the middle of its fire. But then he looks at John, at Molly, at Lestrade, and realises they all have different opinions on Sherlock the man as well. Lestrade thinks there is the capacity there for someone human to emerge. Molly seems to see Sherlock as entirely human sometimes, with needs that any human would have. John thinks, inconsistently to be sure, that Sherlock is nothing but a calculating machine. He said it to Mycroft himself, after the events of The Woman: He doesn't feel things that way…I don't think. And yet he follows Sherlock every single time, and Mycroft cannot see him stopping.

He is not the only one. This should be encouraging, that there is no one on the planet who can understand Sherlock Holmes, not his parents, not his best friend, not his brother. And yet Mycroft Holmes is Mycroft Holmes and he knows everything about everyone. That is his job. That is why, he sometimes thinks, he was born the way he was. There should be no exceptions.

He is sure Sherlock can see the real Mycroft as plain as day, as plain as he can see anyone. He is sure he is not a mystery to Sherlock like Sherlock is to him. He is sure no one is a mystery to Sherlock.

And how can he cope with this chaotic enigma of a brother? How is he meant to guide Sherlock like an older brother is meant to do when he does not have a feel for him, does not understand him? He cannot. All he can do is let Sherlock lead the way and try and sort things out as they go along. All he can do is attempt to reign him in when it all gets too dangerous. All he can do is administer the cure afterwards rather than take any preventative measures beforehand.

This is not easy. This cannot be done without the most terrible of mistakes, of misunderstandings. And so Sherlock loathes Mycroft, and Mycroft perpetually does not understand Sherlock, and this - oh, this - will always be where their disaster lies.