Others would be flattered. Mineta might be over - the - moon if there's a fanfic that portrays him in a more heroic or likable light, as he's often seen as a bit of a comical and sometimes annoying character in the original series.
There are those who would be critical. Characters like Iida might analyze the fanfic for its accuracy in terms of the My Hero Academia universe's rules and ethics. If there are any inaccuracies, he might be quick to point them out.
Iida would probably be very vocal about any inappropriate or unethical content in the fanfiction. He has a strong sense of justice and propriety, so if there are any elements that go against his values, he would not hold back in expressing his disapproval.
Shigaraki would likely be disgusted if the fanfic made him seem weak or less of a threat. He'd probably scratch at his neck in irritation. Dabi would be dismissive. He'd think fanfics are just a waste of time and not worthy of his attention. Toga, though, might be intrigued. If the fanfic had a lot of blood and gore in it, or if it focused on her relationships in an interesting way, she could be really into it.
They may be either amused or annoyed. It depends on how they are portrayed in the fanfiction. If it's a positive and creative portrayal, they might be amused. But if it's a negative or inaccurate one, they could be annoyed.
Some characters might be flattered. For example, Izuku Midoriya would probably be really shy but also a bit happy that people are so interested in his story and his growth as a hero. He might see it as a sign that he's making an impact.
Some characters might be amused. For example, Denki Kaminari would probably find the wild and creative stories about his electric powers really cool and get a good laugh out of them. He's the type who enjoys a bit of fun and absurdity.
Some might be entertained. They may enjoy seeing the different scenarios that fans come up with. Like Vaggie, she might be initially skeptical but then get drawn into the creativity of it all.
Jean might be a bit embarrassed. If the fanfic has some romantic or over - the - top heroic scenes about him, he'd probably blush and try to act like he doesn't care, but secretly he'd be a bit flattered. He's always had an ego, so while part of him would be like 'this is so cheesy', another part would enjoy the attention.
For Todoroki, if he saw fanfiction that delved into his family issues in a new way, it could make him more self - reflective. He might start to think about his past and his relationship with his father from different angles, which could potentially lead to him having a more nuanced view of himself and his place in his family.
Deku would be devastated. He has always seen Bakugo as both a rival and someone he deeply cares about. His reaction would likely be a mix of extreme grief and guilt. He might feel that he could have done more to protect Bakugo. Kirishima, who is Bakugo's friend, would be heartbroken. He would probably be filled with anger towards whatever caused Bakugo's death and would be determined to make the culprit pay. Ochaco and the other classmates would also be in shock. They would come together to support each other through the difficult time, but they would also feel a great sense of loss as Bakugo was an important part of their class dynamic.
Some would be shocked. Take Nancy, for instance. If she saw fanfiction that delved into her romantic relationships in new and unexpected ways, she might be taken aback. She's used to her story being told a certain way in the show, and this new take would be quite different.