There is some. I've seen some on Wattpad as well. Some focus on how Nejire's bubbly personality might interact with Deku's more reserved and determined nature. It's really interesting to see how different authors imagine their relationship developing. For example, some might write about them meeting during a hero event and gradually falling for each other.
There are themes related to self - discovery. As they fall in love, they also discover new things about themselves. For Deku, it could be learning to be more confident in his personal relationships because of Nejire. For Nejire, it might be about finding a deeper purpose in her hero work through Deku. And of course, there are the typical romantic themes like first dates, confessions of love, and dealing with jealousy from other characters.
One possible fanfiction could be about Naruto learning a new jutsu similar to Hado 90 from another dimension. Maybe he meets a strange ninja who teaches him this powerful technique. Naruto then has to master it quickly to defend his village from a new threat.
In a Naruto Hado 90 fanfiction, Naruto might find himself in a parallel universe where the ninja world is based on different energy systems, and Hado 90 is part of that system. He has to figure out how to use it while also dealing with the different politics and power struggles in this new world. For example, there could be a powerful clan that wants to monopolize the use of Hado 90, and Naruto has to stop them to protect the innocent. This would involve him making allies, learning the secrets of this new world, and of course, mastering Hado 90.
You can start by looking on popular fanfiction websites such as Archive of Our Own. Just use the search function and type in 'izuku and nejire'. Browse through the results to find the ones that seem interesting to you.
One popular story might be 'Izuku and Nejire's Adventure'. It often has interesting character interactions where they go on quests together and develop a deep bond. The story may also include some sweet moments between them.
For Izuku, start with his insecurities. Maybe he initially feels intimidated by Nejire's powerful quirk. As they interact more, he could learn to be more confident around her and also incorporate some of her fearless attitude into his own hero persona. Nejire, on the other hand, might start off seeing Izuku as just another student. But as she witnesses his unwavering determination, she begins to respect him more. You can show their development through small moments, like conversations during lunch breaks or while waiting for a training session to start.
A good plot could involve Nejire being assigned to mentor Izuku in a special aspect of hero training. As they spend time together, Nejire starts to notice Izuku's unique qualities that are different from what others see. They could also face a villain who targets them specifically because of their potential as heroes. During this difficult time, they rely on each other not just for protection but also for emotional support, and this strengthens their bond.