One way they could interact is if One - Punch Man was transported to New York City (Spider - Man's turf). Spider - Man would initially be confused by this super - strong but seemingly non -chalant hero. He might try to figure out One - Punch Man's motives. As they interact more, they could form an unlikely friendship and work together to protect the city from both normal villains and new threats that might be attracted to One - Punch Man's power.
In a fanfiction, they could also be from different dimensions and accidentally cross paths. Spider - Man could be in awe of One - Punch Man's power, while One - Punch Man could be intrigued by Spider - Man's determination. They could then decide to help each other get back to their respective dimensions while dealing with various threats along the way.
One idea could be a crossover where Spider - Man and One - Punch Man team up to fight a common enemy. Maybe a powerful villain from the Spider - Man universe has somehow made its way into the One - Punch Man world and is causing chaos. They could learn from each other's fighting styles. Spider - Man with his acrobatic moves and web - slinging, and One - Punch Man with his overwhelming strength.
Imagine Pinkie Pie meeting Saitama. Pinkie would be her usual bouncy self, trying to throw a party for him. Saitama would be a bit bewildered by her energy. Fluttershy might be a bit scared of Genos at first because of his robotic appearance, but then she would realize he's not a bad guy. The ponies' way of solving problems through friendship and cooperation would be a new concept to Saitama and Genos. They would learn a lot from each other. For example, Saitama could learn about the importance of having a positive community like the ponies do, and the ponies could learn about self - defense from Saitama and Genos.
The interactions would be quite diverse. Thor might see Saitama as a strange but powerful being. He could offer to have a friendly sparring match, which Saitama might decline because it's too much trouble. Black Widow would likely be trying to figure out Saitama's background and what makes him tick. And Spider - Man would be super excited to meet someone with such incredible power, constantly asking Saitama questions about how he got so strong.
The interaction could be full of humor and action. Imagine Skull from Persona 5 challenging Saitama to a fight, not fully understanding the extent of Saitama's power. Saitama would probably just knock him out with one punch in a comical way. But then the Persona 5 characters could show Saitama the value of teamwork and strategy, which he might not be used to in his solo fighting style. They could also introduce him to their world, and Saitama could introduce them to the strange and wacky world of One Punch Man heroes and villains.
Spider Man would probably be very protective. He'd use his agility and strength to keep the kid out of danger. For instance, if they were in a fight scene, he'd quickly web - sling the kid to a safe place.
In a crossover, Saitama might be the odd one out in the colorful and ink - filled Splatoon world. But his simplicity and straightforwardness would attract the inklings. They would try to get him to embrace their culture, like trying different ink colors. Saitama would just go with the flow. Genos, on the other hand, would be more focused on how the Splatoon world could help him become stronger. He would observe the inklings' and octolings' teamwork during battles. The inklings and octolings would be fascinated by Genos' loyalty to Saitama and might try to understand the concept of a master - apprentice relationship in the context of their own social structures.
Saitama's one - punch ability would completely overpower most of the beings in the Overlord world at first glance. However, Ainz has a vast array of magic and strategic abilities. He could potentially use his knowledge of magic and the terrain in the Overlord world to his advantage against Saitama, even if he couldn't defeat him directly. For example, he could create illusions or traps.
Sii might interact with Genos in a mentor - like way. Since Genos is always looking to improve his powers, Sii could offer some unique insights based on their own abilities. For instance, Sii might tell Genos that sometimes the simplest solution is the best, which could change Genos' perspective on combat.
Saitama and Naruto would have a rather comical interaction. Naruto is very talkative and enthusiastic, always ready to make friends. Saitama is the opposite, very laid - back and not overly expressive. Naruto would probably be constantly trying to engage Saitama in conversations about power and heroism, while Saitama would just be like 'yeah, whatever'. But when it comes to fighting together, Naruto's quick thinking and Saitama's brute force would complement each other well.
The superfamily could interact with Spider - Man in a more helpful way. For instance, if Spider - Man is injured during a fight, Peter's family in the superfamily could offer him shelter and medical help. They might also use their own unique skills (maybe one is good at making gadgets) to help Spider - Man improve his suit or his web - slinging abilities.