One interesting storyline could be the OC's encounter with the TMNT in the jungle and how they team up to face a common enemy. Maybe there's a new mutant or a group of bad guys causing trouble in the jungle.
Well, of course, the Teenage Mutant Ninja Turtles are likely to be main characters. They are usually Leonardo, Donatello, Michelangelo, and Raphael. And then there's the OC (Original Character) who is in the jungle setting. The OC could be a human, another mutant, or some other kind of being.
One interesting storyline could be a female OC who has a special connection to the Jungle Spirit. Maybe she discovers she can communicate with an ancient and powerful spirit that the other Rangers don't know about. This could lead to her having unique powers or knowledge that helps the team in unexpected ways, like finding a hidden lair of the villains.
One idea could be an OC who is a new mutant in the city. They could have a unique power like the ability to control plants. At first, they are scared and confused about their new form and powers, but as the story progresses, they learn to use it for good and join the turtles in their fight against the bad guys.
A snake OC fanfiction could focus on a snake that was experimented on by the Kraang. It gains super - intelligent and psychic powers. The Turtles initially see it as a threat but then realize it just wants to find a place in the world. They help it control its powers and it becomes an ally. It could have a really cool design with purple and green scales from the Kraang experiments.
One idea could be a Winged OC who is from a different dimension and has the power to heal. The OC could encounter the TMNT during a battle where one of them is seriously injured. Another plot could be that the Winged OC is on a quest to find a lost artifact, and the TMNT get involved either by accident or because they also have an interest in the artifact. Or perhaps the Winged OC is a runaway from an evil organization that the TMNT are trying to take down, and they form an alliance.
In some persona 4 oc fanfiction, an OC might be a detective who is secretly investigating the strange happenings in Inaba. This OC could have their own set of skills and resources, and as they dig deeper, they discover connections between the real world and the TV world that the main characters haven't noticed yet. Their investigations could also put them in danger and lead to some intense action scenes.
Another could be an OC with the Omnitrix getting stuck in a parallel universe where the rules of the Omnitrix are different. For example, instead of being able to transform into known aliens, the OC has to figure out how to use new and strange alien forms that are native to that universe. This could lead to all sorts of adventures as the OC tries to find a way back home.
Another could be a love story within the context of the royals. An original character might fall in love with a royal heir. There could be many obstacles such as differences in social status and the expectations of the royal family. But their love overcomes all these difficulties in the end.
One interesting storyline could be about an original character (OC) who is a half - elf with unique magic abilities trying to find their place in the war - torn world of Warcraft. They might struggle between the two sides of their heritage.
A really engaging storyline might be the OC having to train a young rookie. They take this newbie under their wing, but the rookie has some bad habits that the OC has to break. It's a story of mentorship, growth, and the clash of different generations in the WWE world.