Often, it starts with the OC's death in their original world. It could be a tragic accident or some kind of sacrifice. Then, they suddenly find themselves reincarnated as Ash. There might be a moment of confusion as they realize they are in a different body and a different world.
Another plot point might be the relationships the reincarnated OC forms. They could have a different dynamic with Ash's friends like Brock and Misty. The OC might introduce new ideas or ways of thinking to the group, which could lead to some really fun and unexpected adventures.
In this kind of fanfiction, aside from the OC, you'll often see other young trainers. They could be traveling companions or just other kids starting their Pokemon adventures. Legendary Pokemon might also make an appearance. For example, Mewtwo could be involved, either as a friend or a foe to the OC, depending on the story's direction. There might also be a Team Rocket - like group causing trouble for the OC and other characters in the Pokemon world.
There's also 'Reincarnated into Harry Potter's World'. In this fanfiction, the oc brings in new perspectives and interactions within the existing Harry Potter universe. It's full of creative interpretations of magic and how the oc influences the events that we know from the original series. For example, they might change the way certain relationships form among the characters.
If an OC reincarnated as Superman in fanfiction, it would be an amazing transformation. The OC would suddenly find themselves in a world where they are almost invincible. They would have to deal with the public's perception of them, just like Superman does. And they might also bring in some of their own unique traits from their previous life into the role of Superman. For instance, if the OC was a shy person before, they might struggle with the public spotlight that comes with being Superman.
First, create a unique and relatable OC. Give them a distinct personality and backstory. Then, build a vivid game world with its own rules and lore. Also, add interesting plot twists and challenges for the OC to overcome. For example, they could face a powerful boss that requires them to use all their skills and knowledge.
One common theme is self - improvement. The OC, with the help of the system, usually tries to become stronger, whether it's in terms of physical abilities, magical powers or knowledge. Another theme is exploration. Since they are in a new world, they explore different places, cultures and meet new races. For example, in many such fanfictions, the OC might explore a hidden dungeon or a lost city.
One popular theme is self - discovery. The reincarnated OC often has to figure out who they are in this new life, especially if they have memories from their past life. Another theme is changing fate. They might try to avoid the same mistakes or tragedies that happened in their previous existence. And the theme of power acquisition is also common. Maybe in their past life they were powerless, but in the new reincarnation, they strive to gain strength and influence.
Well, if an OC (Original Character) was reincarnated in a DxD (High School DxD) fanfiction, they might bring in new and unique abilities. They could potentially change the power dynamics in the DxD world. For example, if the OC has some special magic or combat skills from their previous life, it could make them a formidable force in the battles against the devils, angels, and fallen angels in the DxD universe.
In a fanfiction where Ash is reincarnated as an Eevee, his journey would be very different. Firstly, his physical abilities would be limited to what an Eevee can do. He couldn't just run around freely like a human. However, his knowledge of Pokémon battles and the world in general would be a huge advantage. He could potentially form alliances with other Pokémon that he knew were strong from his past life. Also, his relationship with Pikachu would be interesting. Would Pikachu recognize him? And how would Ash, as an Eevee, interact with Pikachu now?