A possible plot is that the cat OC is a magical being from a different dimension. It gets lost in the Naruto universe and Naruto helps it. In return, the cat OC teaches Naruto some unique chakra - control techniques that it has from its own world, which gives Naruto an edge in battles.
One idea could be an OC who is a master of a unique water jutsu in Kirigakure. They could be on a mission to uncover a long - lost secret about the village's founding. Another could be an OC who is trying to reform Kirigakure's harsh shinobi training system from within. Maybe an OC with a special bloodline limit that is feared by others in the village at first but then they prove their worth.
One idea could be that your OC team is assigned a special mission to explore an ancient, forgotten ninja temple. Inside, they discover a powerful and dangerous jutsu that other villages are also after. Another is that they have to protect a visiting diplomat from another ninja village who has a secret that could change the balance of power in the ninja world.
A mystery - themed 'the oc fanfic' would also be great. Maybe there's a mystery surrounding the Cohen family's wealth or a long - lost relative that suddenly shows up with a hidden agenda. The characters would have to work together to solve the mystery, and in the process, their relationships would be tested and new alliances formed.
One idea could be exploring an OC's (Original Character) journey to become a leader within the 100's post - apocalyptic world. They could start as an outcast and through their unique skills, like advanced medical knowledge or exceptional hunting abilities, gain the respect of different factions.
One idea could be that Cat and Beck get lost in a magical forest during a theater production rehearsal. They encounter strange creatures that force them to rely on each other more than ever, strengthening their bond.
One idea could be a cat girl who discovers she has special powers and has to use them to save her city from an evil villain. Another could be a cat girl falling in love with a human in a world where such relationships are frowned upon.
Maybe the fem oc has a special power that gets enhanced during her pregnancy. This could attract the attention of Orochimaru who wants to use her and the baby for his evil experiments. Naruto then has to team up with his friends to stop Orochimaru and protect his family.
Perhaps an OC that is a foreign ninja from a far - off land with a completely different fighting style based on music. They use sound waves to attack, defend, and even hypnotize opponents, much like how Jiraiya uses his toad - related jutsu in creative ways.
A villain oc who is a half - human, half - beast hybrid. They were outcast from society because of their appearance and now seek revenge on all the villages. They have unique physical abilities due to their hybrid nature, like super strength and enhanced senses. Or perhaps a villain oc who is a former student of a great ninja but turned against their teachings. They create their own new and dangerous form of ninjutsu that goes against the traditional ways.
One idea could be to create a male oc who is from a small, hidden village that has a unique jutsu passed down through generations. He could come to Konoha to learn more about different ninja techniques and end up forming a team with some of the original Naruto characters. His backstory could involve a family secret related to the village's past.