Here are some plot ideas. Your OC could be a smuggler who accidentally gets involved in a Jedi - Sith conflict when they pick up the wrong cargo. This cargo turns out to be a powerful Jedi relic that the Sith will stop at nothing to get. Or your OC is an alien from a newly discovered species, and they are trying to prove the worth of their species to the rest of the galaxy. They get caught up in a political intrigue within the Galactic Senate. Also, what if your OC is a mechanic who discovers a way to enhance starship engines to make them faster than the Millennium Falcon? But they have to keep it a secret from the Empire while also dealing with rival mechanics who want to steal their idea.
One plot idea could be that your SI OC is a young Force - sensitive being discovered by the Jedi Order, but they have a connection to an ancient Sith prophecy. The Jedi must decide whether to train them or fear their potential for darkness. Another idea is that your OC is a bounty hunter who gets caught in the middle of a power struggle between the Hutts and a new criminal syndicate. They have to use their wits and skills to survive and maybe even tip the balance of power.
A great plot idea could be that your male OC discovers an ancient Sith artifact that has the power to change the balance of the Force. He then has to decide whether to use it for his own gain or destroy it. Another idea is that he is mistaken for a Jedi and is hunted by the Empire. He has to learn about the Jedi ways quickly to survive. Or, he could be part of a rebellion on a small planet that the Empire has overlooked, but his actions draw the attention of the Emperor.
One plot idea could be that your Jedi OC is a long - lost relative of one of the main characters in Star Wars Rebels. For example, a cousin of Ezra. They come to Lothal seeking their family and end up getting involved in the Rebellion. Another idea is that the OC is a Jedi who has been in stasis for years and wakes up during the Rebels era. They have to quickly adapt to the new situation and help the Rebels with their ancient Jedi knowledge. A third idea is that the OC is a Jedi who was trained by a Sith - turned - Jedi and has some unorthodox ways of using the Force that the Rebels are initially skeptical of but later come to rely on.
One idea could be an OC Jedi who discovers a long - lost Jedi technique that gives them unique powers. This could lead to a series of adventures as they try to master it while also facing off against Sith or other enemies who want to steal the knowledge for themselves.
A great plot idea is that the fem OC mercenary discovers a hidden map to a long - lost Jedi temple. However, she has to outwit a group of Sith cultists who also want the map. As she travels across different planets in search of the temple, she teams up with a local resistance group. Along the way, she uncovers secrets about her own past that are linked to the Jedi. This would make for an exciting and complex fanfiction plot.
A common plot idea is the mercenary getting caught in the middle of a galactic power struggle. For example, between the Empire and the Rebellion. They might be hired by one side, but then realize they've been used or that the other side has a more just cause. Another idea is a quest for a valuable artifact. The mercenary could be hired to retrieve it, but face many obstacles and other parties also after it. Or, they could be on a personal vendetta against a powerful crime lord in the Star Wars universe.
A plot could center around Iden falling in love with an outcast. This person could be from a species that the Empire discriminates against. Her relationship with this character would put her in a difficult position within the Empire and force her to question her loyalty. Or perhaps Iden discovers a long - lost Jedi artifact and has to decide what to do with it, whether to give it to the Empire or hide it from them.
Perhaps a fanfiction where a group of gamers create their own custom clone units in the game and then those units somehow become real in the Star Wars universe. They then have to train and lead these unique clones in battles.
Maybe the fem OC is a bounty hunter who gets caught in the middle of the Clone Wars. She is hired by the Republic to track down a Separatist spy, but as she gets closer to finding the spy, she realizes that there are deeper conspiracies at play. The Republic might not be as pure as it seems, and she has to decide which side she really wants to be on.
One plot idea could be that the OC is a secret agent working for the Republic and is assigned to protect Riyo Chuchi during a crucial diplomatic mission. Along the way, they face attacks from Separatist assassins and have to use their wits and skills to keep her safe.