Well, One Punch Man fanfiction can be really interesting. Some fanfictions might explore the backstories of the characters in more depth. For example, they could expand on Saitama's life before he became so overpowered. It's fascinating to see different interpretations of the characters' personalities and relationships. Some fanfictions might also introduce new villains or scenarios that the original manga or anime didn't cover, which can add a fresh perspective to the One Punch Man universe.
Stray Kids, on the other hand, would also be very concerned. Bang Chan, as the leader, would take charge. He might start asking questions to figure out what exactly happened. Felix could be bringing water or something to make Y/N feel better. Lee Know would be standing guard, making sure no further harm comes to Y/N while they are in a vulnerable state.
The villains would have diverse reactions too. Garou might see the fanfic as a source of inspiration for his own 'evil' plans. He might think that some of the ideas in the fanfic could make him an even more formidable foe. However, if the fanfic makes him look like a complete fool, he'd be enraged. Deep Sea King would be confused by the fanfic, not really understanding the concepts that are different from his simple view of the world. But he might also be intrigued by the new versions of himself presented in the fanfic.
When it comes to a fanfiction about Saitama's training days, it has the potential to be really engaging. We could see the evolution of his training methods, perhaps from simple exercises to more complex and extreme ones. It might also explore his interactions with the people around him during that time, if there were any. For example, did he have any mentors or friends who supported or doubted him? This kind of fanfiction can add a whole new layer to Saitama's character and make us appreciate his journey to becoming One Punch Man even more.
When it comes to Genos' abilities, the Avengers would be intrigued. Genos' ability to fire intense energy blasts could be a great asset in battles. Hawkeye might be thinking about how Genos could provide cover fire or take out tough enemies from a distance. But the Avengers would also be a bit worried about Genos' lack of emotional control at times. In his pursuit of power and revenge, he can be a bit reckless. The Avengers would need to work with him to make sure he doesn't go overboard. Also, Genos' loyalty to Saitama would be something they would need to understand, as it might influence his decisions within the team.
Y/N should have their own goals and dreams. If they're interested in becoming an Auror, that can shape their actions and decisions. Their reactions to Draco should be based on their personality. If they're a shy person, they might be more hesitant around him. And make sure their dialogue is natural. Don't make them say things that are out of character just to move the plot along. For instance, if Y/N is a studious type, they're more likely to talk about books or spells when interacting with Draco.
You can find 'One Punch Man' fanfictions on websites like FanFiction.net. It has a large collection of fan - created stories related to 'One Punch Man'. There are different categories and ratings, so you can easily filter and find the ones that suit your taste.