Author's Note: I'm aware that in canon there's a 7 year age difference between Mycroft and Sherlock but it doesn't quite work for this one shot so in this universe, Mycroft is four years older than Sherlock, making him 15 when Sherlock is 11.
Mycroft Holmes was many, many things.
He was intelligent and manipulative, sarcastic and secretive, charming and calculating.
He could twist words into double edged swords and was able to blackmail like the best of them, he had even known how to properly bribe someone since he was thirteen.
Yes, Mycroft Holmes was many things but first and foremost, he was Sherlock's brother and Mycroft would burn the world down for him.
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The day of Sherlock's eleventh birthday was ingrained into his mind like all the etiquette and manipulation he had ever been taught.
It had started out like any other birthday.
He had woken up earlier than Sherlock had so that he could help his mum bake Sherlock's cake and his dad wrap the presents. His parents were understandably excited- after all, one's eleventh birthday was a very significant and special day- for Sherlock to wake up so they could talk (read: pester him) to him about his soul mark.
Sherlock was extraordinary and that meant that his soul mate had to be just as brilliant as him.
It wasn't a surprise they'd all be interested.
But nobody anticipated the events of that day or the way it would affect his brother.
.
.
The first hint was when Sherlock asked to sleep in and skipped breakfast.
The second hint was when he was late for brunch.
The third hint was the red rimmed eyes and the tears that Sherlock wouldn't allow to fall out.
The fourth hint was the rolled down sleeves of his button up.
Sherlock hates having his sleeves rolled down, Mycroft thought grimly, suddenly coming to a startling realization.
His eyes widened and he turned his head so quickly that he gave himself whiplash.
One look at his brothers eyes and he knew.
It took him a moment to come to his bearings- to put it all together and understand what his brain was screaming at him but it was too late.
By the time he had pieced it all together, Sherlock had run out of the room.
The exclamations of worry from their parents were what snapped him out of his thoughts and sent him running after his brother.
.
.
It took him two hours to find Sherlock.
At eleven years old, Sherlock had a fairly capable network of homeless people, socialites and taxi drivers at his disposal.
As smart as fifteen year old Mycroft was, London was Sherlock's playground. For all his abilities, nobody had what Sherlock did.
.
.
It had only been by chance that Mycroft had stumbled upon the park where Sherlock was. He had heard someone he was passing on the street talking about the 'most adorable' curly haired little boy and had stopped them just to demand where they had seen him.
A few minutes later, he found himself staring at the hunched over form of Sherlock.
He took a deep breath and steeled his resolve, slowly making his way over to the bench.
The moment Sherlock saw Mycroft, he threw himself in his arms.
Tears and words spilled out in quick succession, Sherlock's most intimate fears coming to light in mere moments as Mycroft held him close.
Oh Sherlock, was all he could think as he ran his hands through his brothers curls, his heart clenching as he heard the desperate, heartbroken sobs that came between every few words.
.
.
Mycroft Holmes was many things.
Yes, he could be cold and uncaring, cruel and manipulative and everything and anything else people said about him.
But if anybody ever thought he didn't care about his brother, if anybody ever came to the conclusion that he wouldn't kill and die and everything in between for his only sibling, then damn the world and everyone in it.
.
.
Sherlock had disappeared once they got home but that was something that he could worry about later.
First, he had to have a talk with their parents, especially their mother.
Understandably, his mother was horrified, driven to near tears when she found out. She couldn't imagine her baby boy not having someone to love and cherish, someone who would understand him- all of him-, someone who would give their everything for him the way soulmates should, because no matter how different Sherlock was, no matter how he went about things, if anybody deserved a soulmate, it was him; anybody who knew of Sherlock Holmes knew that he was special, anybody who knew Sherlock Holmes- actually knew him- knew that even though he was eleven, Sherlock was someone worth putting the time and effort into.
Because Sherlock Holmes was the kind of person who put their heart in a cage of knives and wore it on their sleeves, waiting for the right people to worm their way in unscathed (mostly, anyways).
Because Sherlock Holmes, once you gained his trust, would go through hell and back for you.
Because when Sherlock Holmes loved someone, he loved them with every part of his being and no matter how fragile his love was at first, as long as you didn't betray him, that fragile love would grow stronger and stronger until you were one of the very few people he would rely on and that, that was a gift within itself.
Because Sherlock didn't trust people.
Because Sherlock was too used to people using him, hating him, bullying him, hazing him, throwing him away.
Sherlock Holmes was a broken boy, but he wasn't unfixable.
Mycroft just had to find the right person to fix him.
.
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That night, long after his mother had read Sherlock to sleep, Mycroft crept into his room.
To anybody but those that knew Sherlock, he looked peaceful, like any other little boy.
But Mycroft wasn't everybody else, Mycroft knew Sherlock with every part of his being and could see it.
He could see the aftereffects of what had happened today. The wall that Sherlock had built to protect himself from others had been reinforced and was now permanent, the cage of knives that housed his heart, its keys thrown away. There was no going back after today, no pretending that everything would be okay because inside, Mycroft knew the truth.
There would always be longing in his brothers heart, always be a wanting for someone to understand him and accept him in his entirety. Mycroft knew that the inevitable would come- his brother would ignore it and hide it for as long as he could but eventually, the depression, the self-loathing and the hatred for anything and everything soulmate related would come and he could only do so much to make it easy for his brother.
But that didn't mean he wouldn't try.
.
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Mycroft gave his brother a soft kiss on the forehead before he slipped out of the room and back into his own.
There wasn't anything he wouldn't do for his baby brother.
It didn't matter what it cost him.
.
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The day Sherlock turned eleven, Mycroft promised himself that he would take care of his brother.
Even if Sherlock pushed him away, even if he hated him, Mycroft would protect his only sibling from the world.
He would stick by his brother for better or for worse because no matter what anybody else said about him, Sherlock was extraordinary and come hell or high water, soulmate or not, Mycroft adored him.
Because Sherlock deserved it.
I hope you enjoyed it! Leave a review and remember not to flame (I'm flammable)!