You could also write a fanfic centered around the relationships between the masters. How do they interact when they're not in the heat of battle? What kind of friendships or rivalries form between them? This could add a whole new layer of depth to the Fate Apocrypha universe.
Another interesting concept is to create an alternate ending. Maybe the two factions end up working together against a greater threat that was hidden all along, like an ancient evil that awakens during their battle.
The combination of two very different universes. Naruto has its own unique ninja world with various jutsus and clans, while Fate Apocrypha has the concept of Servants and the Holy Grail War. When these two are merged in a fanfic, it creates a whole new and exciting story. For instance, seeing Naruto characters participate in a Holy Grail War or interact with Fate Servants is really cool.
Another concept is a more comical crossover. Shirou tries to adapt to the different rules and magic in the Fate Apocrypha world. He constantly gets into funny situations as he misunderstands the local customs and magic systems. For example, he tries to cook using Apocrypha - style magic ingredients and chaos ensues.
EMIYA often plays a key role in Fate Apocrypha fanfic. He can be a protagonist, guiding the story with his unique set of skills and experiences. His combat abilities and strategic thinking make him a formidable force in any fan - created scenario.
In Fate Apocrypha fanfic, EMIYA might be given new backstories or motives. This is because fanfic authors have the freedom to expand on the existing lore. They can delve deeper into his past as a hero, perhaps exploring his time as a hero before he became a Counter Guardian. This can add new layers to his character and make him more complex and appealing to readers.
One interesting fanfiction could be 'The Cursed Heir in the Apocrypha'. It might explore what would happen if a new character, an heir with a mysterious curse, entered the world of Harry Potter and Fate Apocrypha. They could have powers that are a mix of both universes and face challenges that no one has ever seen before.
Perhaps a plot where the Holy Grail War from Fate Stay Night gets disrupted by the arrival of some key players from Fate Apocrypha. This could lead to new alliances and rivalries. Like Shirou from Fate Stay Night having to team up with a character from Fate Apocrypha, say Sieg, to face a common enemy that is after the power of the Grail in both their worlds.
A possible plot for the 'stay night and apocrypha crossover fanfic' is a story of redemption. A character from 'Apocrypha' who has made some bad choices in their own story, could find a chance at redemption in the world of 'Stay Night'. They could team up with a character from 'Stay Night' like Shirou, who is known for his selfless nature. This would lead to character development for both as they face challenges together. Also, the different magic systems in both series could interact in interesting ways, like how the Reality Marble in 'Stay Night' might be affected by the unique magics in 'Apocrypha'.
Well, you could write a fanfic about Attila's relationships. For example, how he forms alliances or rivalries with different heroes or villains in the Fate world. You might also consider a story where Attila discovers a new power or ability and how that changes his role and interactions within the Fate storyline.
A great plot for a Fate Tiamat fanfic could be a scenario where Tiamat tries to adapt to the modern world within the Fate universe. She has to deal with human culture, technology, and the other strange things she never encountered before. This could lead to some comical as well as deep and meaningful interactions with the other characters.
One unique feature is the blend of different hero - spirit concepts. In these fanfics, you can see how the Servants from both series interact, like a Servant from Fate Stay Night meeting one from Fate Apocrypha and having to figure out their differences and similarities.