Issei could be a bit nervous at first. He might worry about what his classmates will think. But if they show positive reactions, he could become more confident and start sharing more about his writing. However, if they react negatively, he may feel a bit down and might even regret that they saw it.
One Piece: The Demonic Epic and One Piece: Unlimited Stamina are both novels where the main character is an ability user and has a strength of D. I can recommend them to you. I hope you like this fairy's recommendation. Muah ~😗
Captain America would probably be very reflective. He might see his past self as a reminder of his long journey and how much he has changed. He could try to offer some words of wisdom to his younger self.
I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.
Some gods might be entertained. For instance, Hermes, being the trickster god, might enjoy seeing the different and often humorous takes on the gods in the fanfiction.
Peter could also be very nervous. He's still a young hero and being called by the Avengers in such a public setting like in class could make him feel self - conscious. He might stutter when he tries to answer their call and fumble with his things as he gets ready to leave. He'd be thinking about all the possible things they could need him for and whether he's really up to the task while also dealing with the eyes of his classmates on him.
Some students in Peter's class might be really excited as they get to see new takes on their favorite movie. Others could be a bit confused if the fanfiction is very different from the original story.