Deku's experiences with being bullied for not having a quirk. This would be important because it shaped Deku's character and his insecurities. Aizawa might focus on this to better understand the root of Deku's drive and his sometimes over - eager nature to prove himself. It also gives Aizawa more insight into why Deku is so desperate to be a hero despite the odds.
There could be a sense of envy among some classmates. Just like how Todoroki has his own family issues related to his powerful father, Midoriya now has a connection to a respected teacher. This could cause some tension, especially if Midoriya starts getting special treatment from Aizawa during class or training.
Some classmates might be understanding. They could have been taught to be inclusive and kind, so they don't make a big fuss. However, there are also likely to be some classmates who are curious or even a bit mean. They might tease the child, not fully understanding the situation.
Well, in fanfiction, his classmates' reactions can vary widely. There are those who are his friends and they would be supportive. They might cover for him when he has to run off to be Spider - Man. On the other hand, there could be classmates who are envious. They might spread rumors about him or try to expose his secrets just out of spite or envy. And then there are the classmates who are just indifferent. They don't really care about Peter's secret life and just see him as an ordinary classmate most of the time.
His classmates would probably be very concerned. Some might immediately run to get the teacher or the school nurse. Others might gather around Peter, asking if he was okay and trying to comfort him.
He could be surprised. Maybe there are aspects of Deku's past in the fanfic that Aizawa wasn't fully aware of. This new knowledge might make him view Deku in a slightly different light, perhaps with more understanding of his motives and fears. It could also make him more determined to support Deku in the future, both in the fanfic's storyline and in his own mental image of Deku.
He would probably be quite amused by some of his past antics. For example, his constant pranks on Iruka-sensei. But at the same time, he'd also see the pain he carried from not having his parents and realize how that influenced his actions. He might react with a bit of regret for some of the stupid things he did out of loneliness, but also be glad that those experiences made him who he is today.
Some of Percy's classmates might be in awe of Annabeth. She's smart and confident, so they could be a bit intimidated at first. But then they start to admire her for her knowledge.