Harry Potter himself is often very popular. Fans love to write about his further adventures in this combined or alternative universe. Hermione Granger is also a favorite as she can use her intelligence to navigate the new and complex situations that come up in the fanfictions.
Well, one unique feature is the blend of different magic systems. The Harry Potter magic is quite different from that in Fate/Apocrypha, and in these fanfics, seeing how they interact and sometimes clash is really interesting.
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.
A reaction fanfiction in Fate Apocrypha could explore the characters' responses to various events. For example, how the Servants react to unexpected twists in the Holy Grail War. It might be interesting to see how characters like Siegfried or Mordred would react to a rule change in the war.
An OC (Original Character) in Fate Apocrypha fanfiction can bring fresh perspectives. It allows fans to explore uncharted territories within the Fate Apocrypha universe. For example, an OC could be a new Servant with a unique backstory and abilities, which might interact with the existing characters in interesting ways. Fanfiction writers often use OCs to fill in the gaps they feel exist in the original story or to create their own unique story arcs that still fit within the overall theme and lore of Fate Apocrypha.
There's also 'Mystical Alliances in Potter and Apocrypha'. In this fanfic, the plot focuses on how the two different magical worlds deal with a common threat. It has great character development for both Harry Potter and Fate/Apocrypha characters.
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.
One popular trope is the 'hidden power' trope. The OC might start off as an unassuming character but gradually reveals a powerful and unique ability that changes the course of the Holy Grail War. Another is the 'love interest' trope, where the OC becomes romantically involved with one of the canon characters, adding a new layer of drama to the story.
Archer Emiya in Fate Apocrypha fanfiction often showcases his complex personality. He is a hero who has a strong sense of justice. In fanfictions, he might be depicted in various scenarios, like his battles and interactions with other characters. His skills as an Archer, such as his Unlimited Blade Works, are often a focal point. Writers may explore how he uses his abilities in different situations compared to the original story.
Well, cultural clashes are also a common theme. When Fate Apocrypha crosses over with another series, say from a different country or with a very different cultural background, there are interesting cultural exchanges and clashes. For instance, if it crosses over with a historical or myth - based series, the different interpretations of the same myths or historical events can be explored. And of course, the theme of survival is often there. Characters have to find ways to survive in the new and often dangerous situations created by the crossover.