Many of the characters in My Hero Academia are quite complex. In a War Arc fanfiction, Shoto Todoroki might have an interesting reaction. If the fanfiction explores his relationship with his family during the war, it could bring out a range of emotions in him. He might be relieved if it shows him growing closer to his family, or he could be angry if it misinterprets their interactions. And villains like Dabi would also have their own reactions. If the fanfiction shows his motives and actions during the war in a new light, he might be either intrigued or enraged, depending on how it's written.
Well, some characters might be shocked. For example, Deku would probably be very concerned about how he's portrayed in the fanfiction. He might be a bit embarrassed if it shows his more vulnerable moments during the War Arc. Bakugo, on the other hand, could be angry if the fanfiction doesn't show his strength accurately. He's all about being seen as powerful, so any misrepresentation might tick him off.
Some characters like Tsuyu would be quite level - headed in their reactions. She might simply take the fanfiction as an interesting take on the War Arc. If it has some inaccuracies, she might just shrug it off as creative license. But for characters like Mineta, he could be all over the place. He might be excited if he's shown as more heroic than he actually was in the War Arc, or he could be sulking if he's made to look like a fool.
The heroes in MHA like All Might might view Dabi fanfiction with a sense of concern. All Might has always been about justice and the greater good. He might see Dabi fanfictions as a sign of how some people are attracted to the darker side of the hero - villain dynamic. He could worry that it might influence younger fans in the wrong way. However, villains in MHA might have different reactions. Shigaraki could see Dabi fanfictions as a way to understand how the public perceives Dabi and use that knowledge to his advantage in his evil plans.
For the teachers in My Hero Academia, like Aizawa, he would probably be indifferent to most ships fanfiction. But if there were ships that involved his students in inappropriate or unethical ways in the fanfiction, he would be very concerned. Otherwise, he would just see it as another strange aspect of the fans' creativity and leave it at that.
Well, some of the characters might be really excited. Deku, for example, would probably be super interested in the different powers and hero concepts in Marvel fanfiction. He might take notes on how Marvel heroes use their powers and try to find ways to apply similar ideas to his own hero journey.
On the other hand, Bakugo might be enraged. He's a prideful character and if the fanfiction misrepresents him or shows him in a way he doesn't like, he could get really angry. He might even go on a rant about how inaccurate it is compared to his real self and his ideals of heroism. Also, if the fanfiction portrays him as weak, that would definitely set him off.
Then there are those like Izuku Midoriya. He might study the fanfiction from a different perspective. Since he's always analyzing quirks and hero strategies, he could look at how the authors in fanfiction have reimagined the characters' quirks and relationships. He might even get some inspiration from it for his own hero analysis notebooks.
The students of Class 1 - A would have a range of reactions. Ochaco might find the romantic elements in the fanfiction really sweet, especially if there are any cute ship moments. Iida would likely be concerned about whether the fanfiction adheres to some sort of moral code. He might be nitpicky about things like fairness and justice within the fictional story.
The characters would have a range of reactions. Some would be in disbelief. They have witnessed Deku's journey from a quirkless boy to a powerful hero - in - training. So, seeing him as a villain in a fanfiction would be like a complete 180 - degree turn. Midoriya's mother would be devastated. She has always supported her son, and to see him as a villain would go against everything she believed in. The teachers at U.A. would be concerned and start to analyze what could have led to this change. Maybe they would question their own teaching methods or if there were any signs they missed during Deku's time at the school.
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.
Well, Bakugo might scoff at first. He'd probably think Batman is too brooding and not as straightforward as he likes his heroes. But then as he reads more of the fanfiction, he might grudgingly admit that Batman's detective skills are cool. Deku, on the other hand, would be super interested. He'd be analyzing every move Batman makes in the fanfiction, taking notes in his head about Batman's strategies and how they could be applied in his own hero work. Uraraka would be more focused on the relationships in the fanfiction. She'd be all 'aww' at the cute moments and feel for the characters when they're in trouble.