Obviously, King himself is a very popular character in 'One Punch Man King' fanfiction. He is often the center of the story, whether it's about exploring his mysterious powers or his relationships with other heroes. Another popular character is Saitama. Since they are both part of the hero association, there are many fanfictions that involve their interactions, like Saitama being curious about King's supposed feats of strength.
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 popular aspect in One Punch Man subterranean fanfiction is the re - imagining of the subterranean races. Writers often give them more complex backstories and motives. For example, some fanfics might depict a subterranean character who has a change of heart and decides to side with the surface - dwellers. This adds an interesting layer of depth to the story as it challenges the traditional view of the subterranean as simply enemies in the original work.
Yes, there likely is. The Naruto and One Punch Man fandoms are both quite large, and it's common for fans to create crossover fanfictions. These crossovers can be really interesting as they combine the unique elements of both universes, like Naruto's ninja skills with Saitama's one - punch power.
I'm quite sure there exists a 'Naruto is One Punch Man' fanfic. The world of fanfiction is vast and full of all kinds of creative crossovers. Writers might be intrigued by the idea of bringing Naruto's ninja skills and the unique world of One Punch Man together. For example, how would Naruto react to the overpowered villains in One Punch Man's world? And how would Saitama view Naruto's determination to protect his village? These are the kind of things that could be explored in such a fanfic.