Well, there would be the boys themselves who are the central characters. They are likely to be curious, brave or perhaps a bit rebellious as they choose to wear tight corsets which is not a common thing for boys to do.
It depends. Some people love Corset Story corsets for their style and fit, but others might have issues with sizing or comfort. It really varies from person to person.
Spiderman has his super strength, agility, and the famous spider - sense. In comparison, MHA characters have a wide variety of quirks. For example, Todoroki has his ice and fire powers. Spiderman's agility might be on par with some of the more acrobatic MHA characters like Sero. But his spider - sense gives him an edge in combat that most MHA characters don't have. However, quirks like All Might's super strength can rival Spiderman's own strength.
Deku is quite popular. His journey to become a great hero can be easily translated into a gaming context, like him leveling up his skills. Bakugo is also a favorite. His brash personality and powerful quirk make for exciting scenarios in fanfictions.
Izuku Midoriya is really popular. His journey from being a quirkless boy to a powerful hero - in - training is very inspiring. Katsuki Bakugo is also popular. His explosive personality and strong power make him stand out. And Ochaco Uraraka with her cute appearance and kind heart is liked by many.
Uraraka would probably find it really interesting. She has a positive and curious nature. She'd be excited to see how the changes in backstories affected the relationships between the characters. And she might even share her thoughts about it with her friends in the MHA universe.
Some MHA characters might be really intrigued by Disney fanfiction. For example, Izuku Midoriya would probably be super excited. He loves stories and analyzing different characters' motives, just like he does with heroes. He'd be all about exploring the new worlds and character relationships in the Disney fanfics.
The MHA characters' reactions could vary widely. For instance, All Might might see the Naruto fanfiction as a great source of inspiration. He could admire the way the characters in Naruto strive for their goals, just like heroes in their own world. Todoroki might be a bit detached but still interested. He'd analyze how the power systems in Naruto compare to quirks in their world. Mineta would probably be more interested in any fan service - like elements if there were any, but that's not a very positive reaction. Overall, it really depends on each character's personality.
I don't know for sure as it depends on the specific fanfic. It could be a main character from the original My Hero Academia series who is put in a new and difficult situation that makes them 'broken but not defeated'.
There could also be a theme of transformation. The act of wearing a tight corset can physically and metaphorically change the boys' appearance and perhaps their perception of themselves. This can be explored in terms of how they adapt to this new 'look' and what it means for their relationships with others.