The relationships between the characters can also be an interesting concept. In the fanfic, characters who may not have interacted much in the original could form strong alliances or rivalries. It can show how different personalities clash or complement each other in unexpected ways.
Another plot idea might be to focus on Shirou's internal struggle during the Grail War in more depth. Show how his ideals are tested not just in battle, but also in his interactions with other Masters and Servants. Maybe he has to make some really tough moral choices that could change the course of the war.
Servants are also often main characters. For instance, Saber, with her noble and powerful presence. In the fanfic, she might have different relationships with other characters compared to the original. Her backstory and her connection to the Grail War are important elements that make her a main character.
One interesting concept is alternative Servant summonings. For example, seeing a different class for a well - known character like if King Arthur was summoned as a Caster instead of a Saber. Another concept could be different Masters, perhaps a non - traditional or more morally ambiguous Master. And then there are the alternate storylines that might change the location or rules of the Holy Grail War.
Another plot could involve Shirou getting a glimpse into the past of the Grail War through some sort of magical artifact. He discovers secrets that were long buried and this knowledge could either help him in the war or put him in greater danger as others may want to silence him.
One interesting concept could be the different universes that the characters cross over from. In such a fanfic, the Counter Guardian Emiya might bring unique abilities and a complex backstory from his original 'Fate' universe. For example, his time - traveling and combat skills can create exciting action scenes when combined with the elements of the crossover world.
The plot could involve Emiya's discovery of secrets within the Grail War. He might find out that the Grail has been corrupted in ways not known in the original story. This could lead him on a quest to either purify the Grail or stop the war altogether. Also, his relationship with other Servants like Saber could be different. Instead of the typical rivalry, they could develop a mutual respect and a friendship that transcends the war. Emiya might also use his unique skills and abilities in new and creative ways. He could combine his projection magic with some other power he discovers during the war to gain an edge against his opponents.
First, you can give Shirou a new backstory. Maybe he has a different family history or a unique experience that shaped him. This will make his character more distinct. For instance, if he was raised in a different part of the world, his views on heroism might be different.
The Emiya ending in the Fourth Grail War fanfiction often shows his complex character. He is a hero with a strong sense of justice. In this ending, he might face difficult choices. Maybe he sacrifices himself to save others, which is in line with his selfless nature.
Well, perhaps in this fanfic, Emiya has to face some moral dilemmas during the fourth war. He might be forced to make choices between saving civilians and achieving his goals in the war. Also, his relationship with his Master could be explored in a new light. What if his Master has a hidden agenda that conflicts with Emiya's own sense of justice? That would surely add a lot of drama to the story.
The exploration of different magic systems can be really cool. Fanfiction writers might expand on the existing magic in emiya wars, or create entirely new types of magic that interact in unique ways with the characters and the world.