One interesting Shirou Highschool DxD fanfiction could be one where Shirou uses his swordsmanship skills from his original story in the Highschool DxD universe to fight in the Rating Games. This would bring a new dynamic as his unique combat style would contrast with the magic - based fighting in Highschool DxD.
There might be a fanfiction where Shirou forms a pact with a unique devil in Highschool DxD. For example, he could make a deal with a devil who has an interest in his ability to project weapons. This would lead to all sorts of adventures and challenges as he has to navigate the complex world of devil contracts while still being true to his own values.
A creative one could be where Shirou's reality marble from the Fate series somehow merges with the Highschool DxD world, creating a really unique and strange new setting. For example, the landscapes from his reality marble start to appear in the DxD world, and the characters have to figure out what's going on. Another creative fanfic might be Shirou being reincarnated as a devil in the DxD world but still retaining his memories and abilities from his past life, leading to some really interesting power - ups and plot twists.
Well, Shirou could form an unlikely alliance with some of the characters in Highschool DxD. Maybe he teams up with Issei and his group. Since Shirou has a strong sense of justice, he could help them in their battles against stronger enemies. He might also teach them some of his combat techniques, like how to better utilize their own powers.
One interesting 'Highschool DxD Tiamat' fanfiction could be the ones that explore Tiamat's character in the context of the Highschool DxD universe. For example, some fanfictions might focus on her relationships with other characters like Issei. They could show how she adapts to the school environment and the chaos that often ensues in the Highschool DxD world. Another aspect could be fanfictions that delve into her powers and how they are perceived and used within the story. Maybe she uses her powers to protect the school or to help a particular character achieve their goals.
One interesting Azazel fanfiction could be one where he mentors the main character in a more in - depth way, exploring his knowledge and skills. For example, a story where he takes the protagonist on a journey through different dimensions to teach about the various supernatural elements in the Highschool DxD universe.
There might be a fanfiction where Fem Issei has a special power that only she, as a female version of Issei, can possess. For example, she could have a more refined form of the Boosted Gear that is attuned to feminine energy. This could lead to new storylines and battles that deviate from the original plot. She may also form unexpected alliances with other characters based on this new power.
One interesting fanfiction could be where Female Issei has to face unique challenges in the supernatural world that are different from the male Issei in the original series. For example, she might have to deal with discrimination in a male - dominated underworld society.
A great fanfiction could be a 'what - if' scenario. What if a certain event in Volume 10 had a different outcome? Maybe a character who was supposed to be defeated actually won, and the fanfiction could explore how that changes the entire dynamic of the story and the relationships between the characters.
One idea could be Shirou using his projection magecraft in the Highschool DxD world to create unique weapons during battles against the devils or fallen angels. For example, he might project Excalibur to fend off a powerful devil attack. Another plot could involve Shirou forming an alliance with Issei and his group, teaching them about his different combat techniques and how to better strategize in fights. He could also have a romantic sub - plot with one of the female characters from Highschool DxD, like Rias, where his noble and self - sacrificing nature attracts her.
Shirou would fit in as a powerful and unique addition. His combat skills and magecraft would make him a formidable ally or opponent. He could use his projection abilities to create various weapons and tools, which would be very useful in the battles that often occur in the Highschool DxD world.
One possible fanfiction could involve Shirou being transferred to the Highschool DxD world and somehow obtaining Excalibur. Maybe he has to use it to defend the school from a new threat that the regular characters can't handle on their own. This would lead to some interesting interactions between Shirou's abilities and the magic and powers in the Highschool DxD universe.