Mycroft was used to being on his own. Really he had spent his entire life that way. The first seven years as an only child, realising slowly that he didn't work quite the same way everyone else did. Realising with a growing horror that he could look at things and make connections that not even the adults around him seemed to be able to do. That he could see the whole world in minute detail. And he had been terrified of his parents finding out. Finding out he was a freak and sending him away. He kept away from other children. Frightened that, with their petty little brains they might tell his parents. Tell his secret.
And then Sherlock had arrived. And the year after that they had sent Mycroft away. And obviously that meant that his parents had decided they liked Sherlock better. Sherlock was probably normal. He was a quiet baby; he hardly ever cried, just regarded the world with large grey-blue eyes and sniffled a bit.
At his first prep school Mycroft had been bullied. Refusing to hit back. Refusing do anything to blow his cover. His exam results were mediocre. He hated sports. He just couldn't see the point of it all. His parent's moved him. And really that was where his life began. By walking smack into Nicholas Garrideb. There had been that briefest of moments when blue eyes had locked on green. A moment of connection. A moment when Mycroft realised he wasn't the only one. He wasn't alone.
For the first time Mycroft wasn't afraid. He went from third from bottom to top of his class. He scored joint highest with Nick on their Harrow entrance papers. Suddenly his parents seemed to notice him. Seemed to be pleased with him. Sherlock was proving to be a precocious, hyperactive nightmare by comparison. And Mycroft took full advantage of that. Full advantage of being able to mediate between his parents and his brother. Being able to handle the situation diplomatically and get both sides to do what he wanted.
Six years. Ages ten to sixteen. Then Mycroft had found he was alone again. Not just alone. That was fine, he'd done that before. Now he was alone and wounded. A huge gaping hole where his heart had once been. The Christmas after Nick had died Mycroft supposed he tried to kill himself. A very amateurish attempt with painkillers and vodka. If he hadn't drunk the vodka he might have succeeded. If Sherlock hadn't been such an interfering little bastard he might have succeeded. If nine year old Sherlock hadn't gone to Mycroft's room because he had heard Nick calling his name he might have succeeded. But he didn't. One stomach pump later and he was still alive and alone.
And then the cold had set in. The bone freezing anger at everything. Mycroft knew how to play the game. And he played not just to win, but to annihilate his opposition. With every political success, every step up the ladder, Mycroft moved further away from the lonely bullied little boy he had once been.
He sometimes caught himself and wondered what Nick would think about it all. Would he have approved? What would Mycroft have been like if he still had his heart? Certainly he wouldn't be sat on his own in his empty house, desperate for the still precocious, still hyperactive, still nightmarish brother who despised him, to commit another atrocity so that Mycroft could be reminded there was someone almost like him in the world.
Perhaps he'd been shown a glimpse of what it could have been like. Perhaps it was just wishful thinking. But he knew he couldn't change. Not now. He was so far up the tree if he fell he'd break his neck. Somewhere at the bottom Mycroft knew his seven year old self was still sat up a corner, hugging his knees and sobbing. And the only thing he had left in common with the boy he used to be was that they were both, irretrievably alone.