The theme of sacrifice often appears. Genma might be in a situation where he has to sacrifice something for the greater good of Konoha or his friends. Also, the exploration of Genma's place in the ninja hierarchy is a theme. How he fits in among the other powerful shinobi in the village is something fanfictions like to play with.
One common theme is mentorship. Genma can be seen as a mentor to Naruto, guiding him in his ninja journey.
One common theme is loyalty. Genma is often shown to be extremely loyal to the Hidden Leaf village in fanfics. Another theme is friendship, as he forms bonds with other characters. For example, his relationship with his comrades in Team Ro is often explored.
Some Genma and Sakura Lemon fanfictions may also focus on the 'forbidden love' aspect. Given that they might not be an obvious or expected couple in the original Naruto story, the idea of their relationship being something that goes against the norm or is not easily accepted by others can be a central theme. This can add an element of drama and tension to the fanfiction.
One common theme is friendship. They might explore how Genma and Sakura could become friends in different scenarios, like during a mission or in the village.
One common theme is self - discovery. Genma often goes through a journey where he learns more about his abilities and himself. For example, in many fictions, he might face a difficult situation that forces him to reevaluate his skills.
An OC with a strong and independent personality would be great. For example, an OC who is a skilled ninja in her own right, like a master of stealth or a powerful genjutsu user. This way, she can match Genma's abilities and they can have an equal partnership.
One interesting storyline could be Genma as a mentor to a young ninja. He could pass on his unique skills and knowledge. For example, his kenjutsu skills can be taught to a new generation, adding a new dimension to the story.
Naruto might initially be a bit jealous that Genma is spending so much time teaching Sakura. But as he sees Sakura improve, he starts to respect the process. Genma, on the other hand, might see Naruto's potential through his connection with Sakura and start to offer some indirect advice to Naruto as well. Sakura would grow to have a new level of respect for Genma as her teacher.
In this fanfiction, Genma could be teaching Sakura about the history and traditions of the ninja world that she wasn't fully aware of before. This could include things like the origin of certain clans and their significance in the overall ninja society. It might also help Sakura better understand her place in the village and among her peers.
One possible storyline could be that female Naruto, with her determination and unique abilities, teams up with Genma on a dangerous mission. Maybe they have to infiltrate an enemy stronghold. Genma's combat skills and female Naruto's unpredictable ninja techniques would make for an exciting adventure as they face various challenges and learn to trust each other more along the way.