Perhaps the fanfiction plot could be set in a parallel universe within the FSN framework. Shirou and Female Hercules are the only ones who can stop a catastrophic event from occurring. They have to travel through different realms, each with its own set of rules and dangers. Their different backgrounds and abilities complement each other, and they form a strong bond as they strive to prevent the disaster.
The plot could involve Shirou and Female Hercules on a quest. They might be searching for a powerful magical artifact that has the potential to either save or destroy their world. Along the way, they face various challenges that test both their physical and mental strength. Their relationship evolves as they rely on each other to overcome these obstacles.
In a fanfiction of Shirou and Female Hercules in FSN, it could explore their relationship in a more romantic light. Imagine Shirou being in awe of Hercules' power at first, but as they spend time together, he discovers her more feminine and vulnerable side. Hercules, on the other hand, might be drawn to Shirou's unwavering sense of justice and his kind heart.
In many of these fanfictions, the theme of growth is prominent. Both characters grow as individuals through their interactions with each other. Shirou might learn to be more assertive, and Female Gilgamesh could learn about humility or the value of others. There's also the theme of destiny. In the Fate universe, destiny plays a big role, and these fanfictions often play with the idea of whether their relationship is fated or if they are defying destiny by being together.
You can try looking on fanfiction websites such as Archive of Our Own (AO3). It has a large collection of Fate/stay night fanfictions, and you might be able to find some featuring Female Gilgamesh and Shirou there. Another option could be FanFiction.net, though the content there may vary in quality and quantity compared to AO3.
Well, one reason could be Shirou's recklessness. He often jumps into dangerous situations without fully thinking things through, and Saber, being a more strategic and experienced fighter, might get mad at his impulsive behavior. For example, when he decides to face powerful enemies alone, endangering not only himself but also the overall mission they are on.
Perhaps the plot involves the Muses using their powers to attract Hercules. They could be singing and dancing around him, and Hercules, being the strong hero he is, is initially a bit confused by their attention but then slowly gets drawn into their world. It could also include some sort of adventure where Hercules and the Muses have to work together against a common foe while their relationship develops.
Well, it could be about Shirou getting involved in the Sekirei battles. Maybe he uses his skills from his original story to help or compete in the Sekirei world. For example, his sword - fighting abilities might give him an edge in combat against other Sekirei or their Ashikabi.
The plot could revolve around their adventures together as a married couple. Maybe they discover a new magical threat and have to use their combined powers and skills, with Shirou's swordsmanship and Rin's magic, to protect their world. They also might start a family and raise a child with magical abilities, passing on their knowledge and values.
Well, perhaps Harry could inherit some of Hercules' super strength. He might use it to fight Voldemort in a more physical way, like being able to lift and throw large objects at the Death Eaters. It could also add an interesting dynamic to his relationship with his friends, as they might be both in awe and a bit intimidated by his newfound power.
Perhaps in the crossover fanfiction, Hercules travels to the world of 'The Little Mermaid'. He meets Ariel and together they face a threat to both the land and the sea. Hercules could use his strength to protect Ariel while she uses her knowledge of the underwater world to help them navigate through various challenges. It would be a great combination of two very different Disney universes.
Perhaps in the fanfiction, Shirou meets the Lady of the Lake during a time of crisis. She could offer him guidance on how to overcome the difficulties he's facing, like dealing with powerful enemies. The story might also explore their relationship, whether it's one of mentorship or something more mysterious.