For the villains in My Hero Academia reacting to fanfic, All For One would see it as a form of entertainment from afar. He might chuckle to himself about how the fans perceive his actions and the world he's trying to create. Overhaul would be enraged if the fanfic didn't show his ideology in the right way. He'd see it as a misrepresentation of his grand plan. Twice would be really confused. He'd be like 'Is this real? Is this how we are?' and would probably go back and forth between liking and disliking it depending on his mood.
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.
The villains in My Hero Academia have different personalities, so their reactions to fanfic would vary. Mr. Compress might find the fanfic concept interesting. He might use it as a way to study how the heroes and other villains are perceived in the public eye.Spinner would be a bit indifferent at first. But if the fanfic somehow related to his admiration for Stain, he might start to pay more attention. Kurogiri would just be there, not really showing much emotion. He might think of it as just another aspect of the world that he doesn't fully understand but doesn't care much about either.
Shigaraki would likely be dismissive. He's so focused on his own goals of destroying the hero society that he'd see fanfiction as a useless distraction. However, if there were elements in the Genshin Impact fanfic that could somehow be related to his own plans, like powerful artifacts or magic that could be used for destruction, he might take a second look.
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.
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.
Toga might be interested in the zombies in a different way. Since she has a fascination with blood, she could study the zombies to see how their blood or 'undead' state works. However, other villains might just be in it for themselves. Dabi, for example, might just burn his way through the zombie hordes without much thought for a grand plan. He'd be more focused on his own survival and causing chaos.
Some students could be inspired. Momo might see how Spider - Man creates his own gadgets in the fanfiction. Since she can create objects with her quirk, she could get ideas for new things to create that would be more useful in combat or rescue situations. And the whole experience might make them more open - minded about different types of heroes and hero stories.
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.
They might be really surprised. Some characters could be flattered by the positive portrayals in the fanfiction, while others might be a bit annoyed if their personalities are misrepresented. For example, Deku might be shy but also happy to see new interpretations of his growth journey.
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.
Midoriya and Toga. It's an unexpected pairing because Midoriya is the symbol of hope among heroes and Toga is a rather blood - thirsty villain. But if you think about it, Toga's admiration for heroes could be a starting point. Maybe she could be redeemed or at least have a moment of self - reflection through her interactions with Midoriya.
Batman in the My Hero Academia world would likely be a bit of an outsider at first. His dark and brooding nature might contrast with the more colorful and often optimistic characters in MHA. However, his intelligence would be highly respected. He could use his detective skills to help solve some of the mysteries that pop up in the MHA world, like the origin of certain quirks or the identity of villains who are hiding in plain sight. And his martial arts expertise would make him a formidable opponent in battles against villains.