Well, some might be really amazed. They could see a new side of Deku that they never knew before. His singing might show a different level of confidence or a hidden talent, so they would probably cheer him on.
Some students in class 1a might be a bit shocked at first. Deku is usually known for his heroic deeds and academic efforts. But when he starts singing in the fanfiction, it's like a whole new aspect of his personality is revealed. Those who are closer to him, like Uraraka, might be really excited and proud, while others like Bakugo might be a bit jealous that Deku has yet another thing he can do well.
They could be super excited. His singing might be really inspiring and make them feel more united as a class.
Bakugo would likely be furious. He'd feel betrayed and would probably be the first to attack Deku, yelling at him about how he's thrown away everything they've worked for. Uraraka might be more empathetic. She'd try to understand what drove Deku to become a villain and hope there's a way to bring him back to the side of good.
Deku might be initially shocked. He's used to Bakugou's aggression, but an actual injury is different. He could be in pain and disbelief at first. Then, he might try to downplay it, especially if he doesn't want to cause trouble for Bakugou, because Deku is generally a very forgiving character.
Eventually, the class might come to understand Marinette's decision. As they struggle to do things on their own, they realize how much effort Marinette had been putting in. This could lead to them changing their ways and maybe even trying to make it up to Marinette if she decides to start helping again.
He might cry a lot. Deku is very emotional, and being cheated on would be a very painful experience for him. He could also get angry, which is rare for him, but this situation would be so unjust that he might not be able to hold it in. He'd probably start to question his self - worth too, thinking that there was something wrong with him that made his partner cheat.
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.
Bakugou might react with his usual anger. He could lash out at the bullies verbally or even physically, which might make the situation worse. For example, if someone makes a snide comment, he could respond with a loud and aggressive retort.
Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
He might be initially shocked. Snape is used to students being intimidated by him, so Hermione's outburst could catch him off - guard. He may glare at her silently for a moment, trying to regain his composure.
They might be really excited, especially if the fanfiction contains interesting new storylines or character developments that they haven't thought of before.