When Mycroft was seven, Father and Mummy sat him down on the sitting room couch and explained that, by methods they wouldn't go into at this age, in six months it was expected that he would have a younger sibling.
They then explained that they had expected to have a younger sibling for him several times, but that each time... Mycroft wasn't quite sure what happened, but the intent was never brought to fruition. Mummy said very solemnly that this was the first time one of his younger siblings had grown this large, and pulled her shirt a few inches above her skirt to show him the small bulge there.
Mycroft didn't want to touch it.
He asked, instead, why they hadn't told him about the other siblings (Mycroft refused to call them children- they had never been born). Mummy looked pained, and Father explained that the doctors had told them that children tended to react badly to the death of a younger sibling.
When his parents were finished, Mycroft climbed off the sofa and nodded, then walked out of the room to talk to one of the maids who was particularly fond of him. A week later a package for Mr. Mycroft Holmes arrived, and he spent the next two days in his room, reading intently a book on sibling mourning.
He understood the principle of probability well enough to know that there was a high chance the embryo (not child) in his mother's belly would go the way of their other siblings. So he wanted to know all he could about what to expect.
When he was done, he closed the book, tucked it under his arm, and went out to the orchard to think. He needed silence to do it properly. After hours of consideration, he came to the conclusion that to care for this child, who would have a high chance of dying before the age of five, would be a foolish thing to do.
Rather than give another human being the ability to tear his heart out, especially a sibling, who would represent a significant part of his own childhood to his subconscious, he decided to keep it safe while he could. He would not bother at all, except that the deep-rooted bond of siblings would hurt to a possibly debilitating extent were it to be broken.
Caring was not an advantage.
Six months later, when he was seven and a half, Mummy and Father went to the hospital. Mummy's belly had grown large and round, and she had taken to her bed four months before. But now, they left Mycroft with a maid to worry on his own.
That evening, Father came home and once again sat him down on the couch in the sitting room. He explained to Mycroft that he had a brother, Sherlock, but that he was very small and had made Mummy very tired, so if Mycroft promised to be very quiet, would he like to meet him? Mycroft nodded and scrambled off the couch to locate his shoes.
When they walked into the room, the first thing Mycroft noticed was his mother, lying worn and pale in a bed, cradling a small bundle in her arms. He looked at them for a long moment, then went to stand by her and peel back the flap of blanket which lay across the child's (not sibling) face.
He was small and wrinkled and red, and his lips made small sucking motions in his sleep. Mycroft ran a finger over them, and the child sucked the tip of his finger into his mouth. The small noises Mycroft hadn't realized the child was making ceased, and he settled in Mummy's arms. Mummy smiled at him.
"He likes you," she murmured, and Father offered to let him hold the baby (Sherlock) if he sat on the chair and let Father show him how. In a few short minutes, he was settled with his brother (Sherlock) in his arms, arm supported by a pillow to help him support the child's head. Mycroft swallowed and allowed pictures to be taken, and swore to himself that no harm would come to this tiny child.
Mycroft had failed. That was all he could think, as he arranged the funeral, as he had a grave dug, as he watched his brother lowered into the ground in a wooden box and accepted condolences. He had failed to keep his brother safe. He'd said too much, he'd paid too little attention, if only he had done something, he should have been able to do something.
Mycroft sat in his chair before the fire, deep in thought, a glass of brandy at his right elbow. His suit coat and waistcoat had been discarded as soon as he returned from the funeral, and he sat in his shirt sleeves and stared dully at the flames.
He had set out to protect him. He'd sworn it, to himself and to baby Sherlock, to protect himself by protecting him. He flashed on the time Sherlock had fallen from a tree and broken his leg, and how numb Mycroft had felt as he raced out to check. That was nothing compared to the emptiness inside of him now.
Mycroft downed the rest of his drink and stood, making his way slowly upstairs. As he undressed for bed, he thought, briefly, that perhaps, somewhere along the way, he'd begun to care. Perhaps, in the end, he had been at a disadvantage.
Moriarty had set out to burn Sherlock's heart. He'd said so, and in the end, he'd done it. So why, Mycroft wondered, as he slipped beneath the sheets, was it a surprise to him that his own heart was also in ashes?