One plot idea could be that the OC is a powerful ninja from a hidden village. She meets Sasuke first during a mission where they initially clash due to Sasuke's brooding nature and her more optimistic outlook. Later, she also encounters Gaara. Gaara is intrigued by her because she doesn't fear him like others. The OC then finds herself in a love triangle, with Sasuke being drawn to her because she challenges him, and Gaara seeing in her a chance for a different kind of connection. As the story progresses, she has to choose between them while also dealing with the political unrest in the ninja world that affects all three of them.
Well, perhaps the OC is a musician who plays at a local café where Gaara often goes to read. Their music catches Gaara's attention, and they start to have conversations about life and dreams. Or the OC could be a volunteer at an animal shelter and Gaara comes in looking to adopt. They bond over their love for animals and that could be the start of their relationship.
Perhaps the OC is a transfer student from a different village. Gaara is intrigued by her different ways and culture. They start to study together about each other's backgrounds. As they do this, they fall in love. The high school setting could add elements like jealous classmates or strict teachers that try to keep them apart, but they overcome these obstacles.
The OC's character can be developed through her reactions to different situations. When she first meets Sasuke, how does she respond to his coldness? Does she try to break through his barriers or is she put off? With Gaara, when she learns about his past, does she pity him or see his strength? Also, give her a moral code. If she believes in always helping the weak, it will affect how she treats Sasuke when he's in a dark place and how she interacts with Gaara's people in the Sand Village. Her hobbies and interests can also be used to make her more three - dimensional. For example, if she loves cooking, she could cook for Sasuke and Gaara, and through that, their relationships can grow and develop.
A plot could involve Itachi coming back to life and trying to make amends with Sasuke while also having to deal with Naruto's newfound power. Itachi sees the bond between Naruto and Sasuke and tries to help them strengthen it further for the sake of the Hidden Leaf Village. He could train them in some of his unique jutsu.
Perhaps in the fanfiction, the female Naruto character has a unique ability that Gaara is intrigued by. They start training together, and during these training sessions, they learn more about each other's personalities. Gaara, who has always been a bit of an outcast, starts to open up to her warmth and determination. Their relationship then blossoms as they face various challenges together in the ninja world.
One idea could be a story where Gaara and Matsuri go on a mission together outside of Suna. They face various challenges that force them to rely on each other and in the process, their relationship deepens. Maybe they encounter a powerful enemy that only their combined skills can defeat.
Maybe in a fanfiction, there is a threat to the entire ninja world that requires the unique skills of both Gaara and Sakura. They are forced to train together intensively. During this time, Sakura discovers Gaara's softer side that he usually hides, and Gaara is impressed by Sakura's determination and medical skills. This leads to a deep emotional connection between them.
A really interesting plot could be that the reader is a healer who is sent to the Hidden Sand Village to help Gaara deal with some after - effects of his past traumas. As the reader uses their healing abilities, they also start to heal Gaara's emotional wounds. This leads to a deep connection between them. Or perhaps the reader is a spy from another village, but when they meet Gaara, they start to question their loyalty and eventually switch sides because of their growing feelings for him.
Another plot could be set in a post - war scenario. Naruto is trying to rebuild the ninja world, and Female Gaara is helping in her own way. They start to develop feelings as they work side by side to bring peace and stability. They could also face opposition from some who don't approve of their relationship, adding drama to the story.
One plot idea could be that the reader is a new ninja in the village and Sasuke is assigned to train them. Through the training sessions, they start to understand each other better and develop feelings. Another could be that the reader has a special power that Sasuke needs to help him in his quest for revenge, and as they work together, love blossoms.