I always get the impression that Sherlock had been bullied while he was in school and that he desperately tried not to tell anyone but Mummy always noticed and tried to help.
I've experienced it, up to year 8/ grade 8. Then it sort of stopped, but I still get the occasional, 'Weirdo' or 'You're not normal' thrown in once in awhile (but now I suppose they're just teasing?). It's not very pleasant guys. If you're a bully, please stop.
Senior school is Year 7 up, so Sherlock is about 11/12 and Mycroft is in Uni. Regarding the lack of a father, I just sort of ignored him, up to you to decide whether he died or walked out on them or is just plain busy that it is difficult to involve himself in their lives.
Enough with the ramble, on with it!
Sherlock's mother had pulled up at the school gates and was waiting for him. She heard some loud voices and she rolled the windows down to eavesdrop.
"Stay away from us you freak!"
"You're such a weird person, we don't want you here!"
"You're not normal!"
She didn't think much of it until she heard her son's voice.
"Leave me alone! It's not my fault you're all so stupid!"
She decided it was time to intervene and she got out of the car. She strode over to the group of them and came up behind her dark haired son. They all immediately shut up. She gave a stern look at the group of them before guiding her son back to the car silently.
The ride back home was quiet. Mummy had hoped that things would be different after changing him to a new school for senior school — she was wrong. It was the same here as it was there. When they had arrived, Sherlock promptly went up to his room. She had decided to give him some time before going up to see him.
"Sherlock?" She whispered while knocking on his door.
"Go away, mummy," he muttered.
"Sherlock, please, come out," she pleaded, "come and walk with me in the gardens," she said gently
There was a silence before she heard some rustling followed by the turning of the lock. When he opened the door, she was faced with a slightly red eyed Sherlock. They were strolling, admiring the crimson autumn leaves when she spoke up, "Sherlock, why didn't you tell me?"
"I didn't want to, mummy, I could handle it myself," he muttered.
"Sherlock," she crooned, "You're not an adult, you can ask for help,"
She heard a small sniffle.
"From who? I'm all alone mummy. I'll always be alone," he tried to put on a neutral voice but it was failing.
Mummy felt a pang of guilt. What had she done wrong? Did Sherlock really think he was all alone? Maybe she should have done something more about the bullying? She had talked to the principal and the teachers but it didn't have much of an effect. She even changed his schools. She sighed — she was at her wit's end.
She gently grasped his shoulders and looked at him a little sadly.
"Sherlock, you have me and Mykee,"
"But no one in school likes me,"
"They don't understand you, Sherly, they're not worth your time. You're just too smart for them. You have a gift Sherlock. You're special. You'll always be better than them,"
She wiped a stray tear from his eyes and gave him a small smile. Sherlock beamed back.
"Now come, darling, I've baked some cookies,"
"I noticed," Sherlock grinned, remarking upon some flour stains on her sleeves.
She gave a small chuckle.
"I also bought a new puzzle for you, shall we try it out?"
Sherlock gave her a Cheshire smile, nodded and happily followed behind his mother.