One idea could be an OC who is a lost spirit in the Unknown. They have the power to manipulate time briefly but don't fully understand it. They cross paths with Wirt and Greg and end up joining them on their journey, causing some unexpected time - loop situations along the way.
Perhaps an OC who is a minstrel from a far - off land in the Unknown. They are on a quest to find a special melody that is said to break any curse. When they meet Wirt and Greg, they believe that the boys might be the key to finding this melody, and so they team up, leading to a series of adventures filled with music and mystery.
Another interesting angle is to focus on the side characters. You could write a fanfiction about the Woodsman's past. What was his life like before he got trapped in the never - ending task of keeping the lantern lit? It could be a tragic love story or something related to his family.
Perhaps the OC is a foreign traveler who comes to visit the Great Wall. While there, they get lost in a restricted area and find a hidden passage. Inside, they find a community of people who have been living secretly near the wall for centuries. The OC becomes involved in their internal politics and helps them deal with a threat from the outside world that could expose their existence and endanger the Great Wall.
Another interesting angle is to write from the perspective of one of the side characters in the show. For instance, the Woodsman. You could delve into his backstory, how he came to be in the service of the Beast, and his internal struggle between his love for his daughter and his fear of the Beast.
A really interesting plot for Wall E and Eve fanfiction could be that they find a baby robot. They then have to figure out how to take care of it, which would be a completely new experience for them. It could lead to a lot of comical and heartwarming moments as they struggle to understand the needs of this new little one. Another plot could be that they encounter a group of rebel robots who are against the idea of humans returning to Earth, and Wall E and Eve have to convince them otherwise. There could also be a plot where they discover a hidden message from the past about the true origin of the plants on Earth, and they go on a quest to uncover the mystery.
Perhaps an OC is a young archaeology student who idolizes Nathan Drake. They manage to get involved in one of his expeditions through sheer determination. Along the way, they learn from Drake and also teach him new things about modern archaeological research methods. It could be a story of growth and adventure for both characters.
One idea could be an OC who is a lightning - style user in Kumogakure and has to face a powerful enemy from another village. The OC could discover a new jutsu during the battle.
A story about an OC who is a healer in the Injustice 2 world could be really engaging. In a world full of battles and destruction, this OC could be trying to heal not only the physical wounds but also the emotional and psychological damage that the characters have endured. They might face challenges like being kidnapped by villains who want to use their healing powers for their own evil purposes.
One idea could be an OC who is a long - lost relative of Aquaman. They have a unique power that helps in a crisis in Atlantis. For example, they can communicate with a special species of sea creatures that no one else can, and this ability becomes crucial in stopping an ancient evil from rising.
An interesting plot could involve an OC who is a super - genius inventor. This OC creates some amazing gadgets that the Thundermans initially don't trust but then realize are really useful in fighting a tech - savvy villain. Also, an OC with the power of invisibility could befriend the Thundermans and help them spy on the villains, leading to some really exciting undercover adventures.
Maybe an OC who is a young entrepreneur trying to start a business in the Boondocks. They face challenges from the local economy and the skepticism of the residents. For example, they want to open a modern coffee shop in an area where everyone is used to traditional drinks. This could lead to interesting interactions with characters like Granddad, Huey, and Riley as they either support or oppose the new business.