Self-Defense
Mycroft only defended Sherlock once from the bullies, bigger boys of twelve and thirteen who couldn't stand to have a slender, arrogant little genius in their neighborhood, paying not a bit of attention to them unless it was to prove how stupid they were. Mycroft was a tall, heavy boy, and he seized two of them by their collars and knocked their skulls together.
Sherlock, lying on the ground and wiping blood away, glared up at his brother. "I didn't ask for your help!" he shouted.
Mycroft loomed over him. "Then learn self-defense, Sherlock. That's an order. You're upsetting Mummy."