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.
On the other hand, characters like Bakugo might be initially angry. He has a prideful nature, and if the fanfiction portrays him in a way he doesn't like, such as being weak or overly sentimental, he'd be fuming. But deep down, he might also be a bit curious about how others perceive him. Bakugo is complex, and while he'd react negatively at first, he could end up secretly reading more just to see what other crazy ideas people have about him.
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.
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.
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 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.
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 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.
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.
RWBY as a whole might find it a fun and different way to experience the My Hero Academia world. They could have group discussions about the fanfictions they've read. For example, they might debate about which fan - created quirk is the most interesting or which character in the fanfiction is the best representation of the original My Hero Academia characters. It could also lead to them thinking about how their own world could be re - imagined in fanfictions by others.