A really cool plot twist in some Geryuganshoop fanfictions is when his psychic powers are not what they seem. Instead of being just for combat, his powers could be linked to a greater prophecy or something. For example, his powers might be the key to saving the world from a far greater threat that even Saitama might not be able to handle alone. This would turn Geryuganshoop from a possible antagonist to a crucial part of the solution.
Well, in some fanfictions, there might be a plot twist where Geryuganshoop is actually from a different dimension and has a mission that is completely different from what we initially thought. He could be trying to protect Earth in his own strange way, which goes against his initial villain - like appearance. This would lead to a lot of interesting interactions with the other characters in One Punch Man.
In some fanfictions, his psychic powers are shown to have a much wider range. He can control more than just the usual objects. For example, he might be able to manipulate time on a small scale using his psychic powers.
One interesting twist could be that a Titan eats a character from One Punch Man and gains not only their physical abilities but also their memories. This Titan then starts to have an identity crisis and tries to rebel against the other Titans. It could lead to a situation where the heroes have to decide whether to kill this unique Titan or try to use it to their advantage.
Another plot twist might be that there is a hidden alliance between some subterranean and a group of surface - dwellers. They are working together in secret to achieve a common goal, perhaps to take down a powerful and corrupt organization. This adds a layer of mystery and conspiracy to the fanfiction.
One unique plot twist could be that Saitama suddenly loses his power and has to learn volleyball skills from the Haikyu characters to regain his strength. Another might be that a powerful monster in One Punch Man is actually a huge volleyball fan and spares the Haikyu characters because he wants to see them play.
One interesting 'One Punch Man King' fanfiction could be where King actually has some hidden powers that he's been suppressing. In this fanfic, he might start to slowly reveal his true strength during a really tough battle against a new and extremely powerful monster. It could be a story that focuses on his internal struggle between wanting to keep his low - key image and having to step up to protect the city.
One exciting plot twist could be Saitama suddenly losing his one - punch power in the Naruto universe. This would force him to adapt to new ways of fighting, like using chakra. Another could be Naruto learning Saitama's training regime and attempting it, only to find it's way beyond his physical limits. And perhaps the villains from both universes team up, making it extremely difficult for the heroes to combat them.
One common plot twist could be that the reincarnated character has some unique power that even Saitama is interested in. For example, they might have a power that can nullify Saitama's strength temporarily. Another plot twist could be that the character is reincarnated as a monster but still retains their human consciousness and tries to find a way to co - exist with humans. Also, a plot twist might be that the reincarnated character discovers a hidden conspiracy in the One Punch Man world that even the heroes don't know about, like a secret organization controlling the appearance of monsters.
In some fanfictions, Garou spares One Punch Man and then teams up with him temporarily to fight a greater evil. This unexpected alliance showcases their combined strength and also explores the dynamic between a self - proclaimed villain and an uninterested hero.
Well, one possible plot twist could be that Saitama's boredom turns into a malicious form. Since he's so powerful and always bored from easily defeating enemies, this new evil side might start creating stronger foes just to have a real challenge, but without caring about the destruction it causes. He could also turn against the other heroes, seeing them as weaklings not worthy of his time anymore.
One plot could be Tornado having to team up with a new, unexpected hero to face a powerful villain that even she has trouble with. This would show a different side of her as she has to work with someone she might not initially get along with.