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.
They would probably have a range of reactions. Some might be excited to see a different take on heroism. Others might be skeptical. For instance, Todoroki could be interested in how the characters in One Punch Man deal with their powers compared to how he deals with his quirk.
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.
Let's think about Bakugo's Explosion Quirk and Spider Man's powers. Spider Man could use his webs to contain and direct Bakugo's explosions in a more controlled way. Bakugo could learn from Spider Man's stealth and how to approach enemies more quietly before unleashing his explosive attacks. Also, Spider Man's spider - sense could help him anticipate Bakugo's more impulsive attacks and react accordingly.
They would probably be very intrigued. RWBY is used to their own fantastical world, and seeing the world of Spider - Man through fanfiction would be a new and exciting experience.
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.
Some of them could be confused. The settings and concepts in Spider - Man fanfiction might not align with what they know. Bakugo might scoff at first, thinking Spider - Man's powers are not as 'powerful' as his own explosion quirk. But as he reads more, he might start to respect the different ways Spider - Man uses his abilities to fight crime.
One way to combine them is by having Spider - Man visit the world of My Hero Academia. He could interact with the students at UA High. Maybe he could teach them some of his unique web - slinging skills or share his experiences of being a hero in New York. This would create an interesting dynamic as the heroes in My Hero Academia have different powers and ways of operating compared to Spider - Man.
The plot of a My Hero Academia Spider - Man OC fanfiction can be developed by mixing elements from both universes. Start with the OC having a normal life until something extraordinary happens, like being bitten by a radioactive spider - inspired creature in the My Hero Academia world. This gives them their powers. Then, they discover that there are other heroes and villains in this world. They decide to train and become a hero. As they progress, they encounter different quirks and have to find ways to use their Spider - Man powers against them. For example, if they face a villain who can turn invisible, they might use their 'Spider Sense' to detect their presence. The plot can also include sub - plots like the OC trying to find a way to reverse the effects of the bite if they think it's a curse at first, or trying to create better web - shooting devices. Along the way, they make friends and enemies, and their story becomes intertwined with the overall narrative of the My Hero Academia world.
Another approach could be to have Spider - Man somehow end up in the My Hero Academia world. He could then team up with the students of U.A. High School. They could learn from each other's fighting techniques. Spider - Man's acrobatic skills and his 'Spidey - sense' would be fascinating to the students, and in return, he could learn about quirks and how to use them in combat.
One way to combine their worlds could be through a crossover event. Maybe a portal opens up between the My Hero Academia universe and the Spider - Man universe. Midoriya could meet Peter Parker and they could learn from each other's powers and fighting styles. For example, Midoriya could be impressed by Spider - Man's web - slinging abilities and try to incorporate some of that into his own combat techniques.