Another storyline could be that Thanos, aware of One Punch Man's power, tries to use the Infinity Stones to either eliminate him or make him an ally. There could be a long - drawn - out battle where One Punch Man has to constantly dodge Thanos' attacks while trying to find a way to land his one punch. In the end, he manages to do it and saves the day.
One possible storyline could be that Thanos arrives on Earth seeking a powerful artifact. Superman steps in to stop him. They battle it out across the city, with Superman using his strength and speed to try and take down Thanos. Another could be that Thanos somehow manages to get Superman under his control using the Infinity Stones, and then the rest of the Justice League has to figure out how to free Superman and defeat Thanos.
One interesting storyline could be that Goku, being the ever - eager fighter, challenges Saitama not knowing the true extent of his power. Saitama, on the other hand, is just looking for a normal grocery shopping day. The clash of their personalities, Goku's excitement and Saitama's nonchalance, could lead to a very comical start. Then as the fight progresses, they both start to respect each other's power in different ways.
In some fanfictions, there could be a situation where Thanos is actually related to an ancient dark magic in the Harry Potter universe. Harry has to figure out this connection and use it to his advantage. Maybe Thanos is after a powerful magical artifact in the wizarding world that he believes will enhance the power of the Infinity Stones. Harry and his friends then have to protect this artifact while also trying to defeat Thanos, which could lead to a series of epic battles and magical duels.
One possible storyline could be Harry arriving in the One Punch Man world and being mistaken for a new hero. He then has to prove himself while also trying to figure out how to get back to his own world.
One possible storyline could be that the original female character is a new hero in the One Punch Man universe. She teams up with Metal Bat on a mission. They start off not getting along well due to their different fighting styles. Metal Bat is more brute force while she might be more strategic. But as they face tougher and tougher enemies, they learn to combine their skills and eventually become good friends or even more.
Similarities? Well, both are super - powerful. They both are often the ones to save the day in their respective universes. Differences? One Punch Man's power is very straightforward - that one punch. Superman has a whole range of powers. In fanfiction, One Punch Man might be more of a comical character in his overpoweredness, while Superman is more of a traditional hero figure.
One unusual pairing in One Punch Man One Piece fanfiction could be Nami and Saitama. Nami might try to use Saitama's strength for her own gain, like getting treasure from really tough - to - reach places. It would be a fun dynamic with Nami's wits and Saitama's simplicity.
There could also be a fanfiction that delves into Garou's past more deeply. Maybe we learn about his family and how his upbringing led him to his current views on heroes and villains. By exploring his childhood traumas and experiences, we can better understand why he is so obsessed with becoming the ultimate monster and how those roots could be the key to his possible transformation in the story.
A common storyline involves a villainess falling for Saitama. Maybe a powerful female villain who was initially out to defeat Saitama realizes his charm and power in a different way. She then joins the harem and has to adjust to the other girls. This creates a lot of tension and humorous situations as the other members of the harem are suspicious of her motives at first.
One possible storyline could be Deku somehow getting Saitama's power in the One Punch Man universe. He might struggle at first to control such overwhelming strength, like accidentally destroying things around him. Another could be a team - up between Deku and Saitama to fight a common enemy that is too powerful for either of them alone. For example, a villain who can absorb powers and is immune to most attacks.