An interesting concept for a 'lost in space oc fanfic' could be an OC who is a psychic. In the vastness of space, their psychic abilities start to act up in strange ways. They can sense danger before it arrives or even have visions of a way back home. But the crew is skeptical at first, and the OC has to convince them of the authenticity of their powers while also dealing with the chaos of being lost in space.
An OC could be a stowaway on the ship in the 'lost in space' universe. This stowaway has a mysterious past and special skills, like being able to communicate with an alien species that the main crew doesn't know about. Their presence could cause both chaos and new opportunities for the crew as they try to find their way home.
Perhaps a key idea in this fanfic is the mystery surrounding the lost primarchs. Their very existence being a secret could be used to create a sense of intrigue. The fanfic might explore how rumors and half - truths about them spread among different factions, and how these rumors influenced the actions and beliefs of various characters.
One idea could be that the OC (original character) is a time - traveler from modern times who has read 'Pride and Prejudice' extensively. She arrives in Austen's world and tries to use her knowledge of the book to her advantage, but ends up changing the story in unexpected ways. For example, she might accidentally introduce modern concepts like feminism to the female characters, which then causes a stir among the society in the story.
One idea could be that the OC has a hidden past that somehow links to Sawyer's own backstory. For example, the OC was involved in the same con that Sawyer was once a part of but on the other side of the deal. This could create a lot of tension and mystery as they interact.
One idea could be creating an OC who is a skilled mechanic from a far - off planet. They could join the crew of the Galaxy One and use their unique mechanical skills to fix and upgrade the ship in ways that the others can't. Maybe they have a special tool that was passed down in their family for generations.
Well, you could have an OC who is an alien with special powers that are different from the normal Semblances in RWBY. For example, they can control gravity in a way that gives them an edge in combat. Or an OC that is a diplomat from a space - faring civilization trying to make peace between different kingdoms on Remnant. Also, an OC who was stranded on Remnant after their spaceship crashed and has to adapt to the world while also trying to find a way back home.
An interesting MCU OC fanfic idea could be an OC who is a journalist. They are always on the hunt for the next big story about the superheroes. This could lead them into all sorts of dangerous situations as they try to get exclusive interviews or expose secrets. Another could be an OC who is a mutant in the MCU (even though mutants are not as prominent yet). This OC would have to deal with being different and feared, while also trying to use their powers for good. And a third idea is an OC who is a reformed villain. They were once on the wrong side but now want to make amends and help the heroes in their fight.
A Sonic OC fanfic could center around an OC who is a healer. In a world full of battles against Dr. Eggman, this OC would use their healing powers to patch up Sonic and the gang after tough fights. They could also have a backstory about how they learned their healing abilities, maybe from an ancient and forgotten tribe in the Sonic world. This would add depth to the character and the fanfic as a whole.
You could write an OC fanfic where the OC is a female assassin. She has a rivalry with Agent 47 at first, thinking he is taking all the good contracts. But as the story progresses, they end up having to team up to take down a powerful criminal organization that is targeting assassins. Her special skill could be hacking into high - security systems to gain access to targets.
A Hiccup OC fanfic could also explore what would happen if Hiccup's OC was from a different tribe. They could have different traditions and skills, and the story could focus on how Hiccup and his friends learn from this new character. For example, the OC could teach them a unique way of dragon training that they've never seen before.