Mycroft was six when he learned he'd be getting a new sibling. His mother happily shared the news with him and his brother. Sherrinford shrugged and wandered off. Mycroft watched his father's expression fall and responded excitedly in response. He didn't feel excited, he felt dread. Mycroft knew this baby would be the last and the result of his mother's wish for a child that had some characteristic that he and his brother were missing.
His father pulled him aside later. "Thank you for acting excited for your mother." Mycroft shrugged so he continued, "I know you're worried so I'll make you a deal."
"What kind of deal?" Mycroft was old enough to know he was being bribed but he was also old enough to know that the baby would come no matter what so he could at least get something in return.
"If you agree to be a good big brother I'll let you name him." His father looked proud of himself for coming up with such an idea.
Mycroft snorted and agreed quickly. After all, Sherrinford often said there was no standard for being a good big brother, as goodness could not be measured. When his father smiled Mycroft wondered what he missed.
The next day Sherrinford tried to hide something bad in Mycroft's room and Mycroft listened to his father yell. He didn't know what the contraband was and was trying to figure it out. When Mycroft heard his father exclaim how horrible a big brother Sherrinford was Mycroft's stomach fell. There may be no way to measure good but that didn't mean there wasn't such a thing as a bad big brother.
Mycroft started school and the other children teased him about his name. He hadn't realized names had importance and meanings. Mycroft was considering not naming his new sibling as an out from the deal. But he'd heard his mother's list of potential names and they were all unusual. The teasing didn't bother him, he was used to Sherrinford teasing him and when he didn't react they said he was weird. It occurred to him as he observed the other children that they were more beast than person. Their teacher spent all her time teaching them about sharing and colours and other tedious things Mycroft already knew. He watched as one of them started crying because they didn't know the answer. Mycroft realized the other children were stupid. None of the others could be told something once and remember it. They also had no idea they were falling into a social hierarchy as they interacted with each other.
Halfway through the third day Mycroft was pulled out of class to speak with a doctor. Mycroft realized this doctor wasn't like the others that he visited for vaccines. He wasn't wearing a white coat and Mycroft wasn't ill. It made him uneasy and he approached cautiously.
After the boring introductions the doctor explained why he was there. "You don't have to worry, Mycroft."
Mycroft knew that meant he had to worry. No one ever said there was nothing to be scared of unless there was; he'd learned that after his first scary movie.
"Your teacher thinks you're special so she called me in to find out. If you are you get to leave that class and go somewhere more interesting."
"Did you make any friends today?" Mummy asked him when she picked him up at the end of class.
"No." Mycroft replied easily. He had no desire to do anything with the other children that would result in friendship. His mother drooped and Mycroft realized that's what she wanted from the new baby. She wanted them to be normal like those other children. It occurred to Mycroft that his mother might get her wish. After all, everyone thought Mycroft was extraordinary; even when compared to his brother. The doctor said he'd never seen anyone like Mycroft which meant he was used to seeing those other children. Mycroft suddenly felt a different sort of dread. He didn't want his sibling to be like them but his parents did. Mycroft had lied to the doctor and told him what he wanted to hear until they let him go back to class. What if his new sibling hadn't known to do that? What if his new sibling was special but too dumb to lie and was taken away? The thought scared Mycroft more than the movie did.
Father always said a man should never go back on his word if he wanted to be trusted. Mycroft didn't know what exactly went into being a good big brother. Clearly he couldn't Sherrinford as an example; he couldn't even use him as an example of what not to do because Sherrinford did many things Mycroft appreciated. Earlier that day Mycroft accidently broke Mummy's favourite vase. Sherrinford lied and said he did it. Later he told Mycroft that their parents were already mad at him. Mycroft thought it was stupid that Sherrinford didn't say Mycroft broke it on purpose to take some of the anger away from himself but Mycroft appreciated it nonetheless.
Since the baby had not been named yet Mycroft technically wouldn't go back on his word if he chose not to name them. But Sherrinford had protected him from Mummy's wrath and Mycroft was still terrified after his encounter with the psychologist. He'd done some reading on psychologists hoping that his fear was irrational and could be eased with facts. Like the fact that there was no such thing as a vampire. Unfortunately his research had the opposite effect. It confirmed Mycroft could have been taken away; indefinitely, if he'd met certain criteria.
Mycroft spent all his free time looking up baby names and their meanings. He needed something normal so if the baby was normal they wouldn't feel bad when they were teased. The name also needed to mean something good, so the baby wouldn't feel bad when they found out. Mycroft resented his name essentially meant small mouth.
He wasn't completely sold on the idea of being a good big brother, a survey of his classmates indicated it was far more trouble than worth, but the baby was moving inside their mother and Mycroft felt he was running out of time if he wanted the perfect name.
Later that night Mummy was talking about how she thought the baby was going to be a girl and that she had the perfect name for a girl: Sherlock. She added that even if the baby was a boy she'd still name him that because she liked it so much.
"No." Mycroft interjected with less horror than he felt.
"What's that dear?" Mummy asked as she turned to him.
"No. Father said if I agreed to be a good big brother I would be allowed to name the baby."
The statement caused an argument between his parents and Mycroft excused himself to look up girl's names. He didn't think the baby would be a girl but that was because he didn't realize it was a possibility. It was obvious; half the children in Mycroft's class were girls after all. Babies clearly came as girls just as often as boys. It was the first time Mycroft had ever felt stupid and he was determined to do something better than burst into tears.
After two months Mycroft still hadn't settled on a name and he was becoming frantic. His father took him aside when he noticed and said, "Don't worry so much. We'll tell the baby how much you worried over their name and they'll know how much you love them. Any name will pale in comparison to how much work you've put into this."
Mycroft hadn't realized the baby would know he had chosen their name. It was much easier to find a name once he had that piece of information but he was still torn between three options if they were a boy.
The baby was born and Mummy was arguing with Father about who would give the middle name. Father always gave them their middle names but Mummy couldn't bear the thought that no one would have the name Sherlock. Mycroft noticed that the baby had stopped breathing during their fight and ran to get a nurse.
The baby ended up in intensive care but wasn't expected to have any problems. "Good thing you were around to protect him." His father made a joke to calm Mycroft down. When Mycroft refused to smile or even take his eyes off the baby he continued, "I want to name him Scott," Mycroft made a face. "But I'm sure you've come up with something better."
Mycroft never laughed at his father's jokes. Mycroft didn't think his father was funny. Mycroft didn't think anyone was funny so it didn't bother his father. Mycroft usually smiled to show he knew it was a joke but he was busy running through different names and applying them to his brother before discarding them. None of them fit. He ran through all the other names he'd seen. Finally he found the perfect one.
"William." Mycroft answered his father's unspoken question. "And you could both give middle names."
"What does it mean?" His father asked.
"Will or desire and helm indicating protection." Mycroft explained.
"That's a good name."
Mycroft heard the tilt in his father's voice that meant he was missing something but he was too busy watching over his brother to worry about it. Whatever the problem was it wasn't with the name. Mycroft had done a lot of research on names. It was a good name.
A/N: Huge thank you to Jump dimension for beta-ing this bad boy. I swapped a couple words after so any mistakes are mine. This is going to be made into a ten story series. I'll load them as chapters here and a series on AO3.