In a Highschool DxD and Shirou Emiya fanfiction, Shirou could end up at the Kuoh Academy. There, he might interact with Issei and the others. His noble ideals would likely contrast with the more hedonistic nature of some of the characters in Highschool DxD. He could also potentially be a powerful ally or a rival depending on how the story is written.
One possible scenario in such a fanfiction could be Shirou Emiya's unique abilities from the Fate series being introduced into the Highschool DxD universe. His projection magic might cause quite a stir among the devils, angels, and fallen angels in that world.
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.
In this fanfiction, Shirou might be seen as an enigma. His calm and collected demeanor would be different from the more boisterous characters in Highschool DxD. He could potentially be a mediator between the different groups, given his own experiences with complex moral situations in the Fate series.
His projection magic might be affected by the different magical rules in the Highschool DxD world. Maybe it becomes more powerful or has some new limitations. For example, projecting holy swords could have a different energy cost or be more effective against certain types of devils or fallen angels.
One great fanfiction could be 'Shirou's New School Adventure in Highschool DxD'. In it, Shirou uses his skills from the Fate series in the chaotic world of Highschool DxD. He might form unique alliances with the characters there, like Issei. It's an interesting read as it combines the two different universes' concepts.
Well, there are fanfictions that explore Shirou's moral code in the context of Highschool DxD's world. For example, he might struggle with the more hedonistic and power - hungry aspects of some of the characters in DxD. He could use his skills as a hero of justice to try and bring some order or a different perspective to the battles and power plays in the DxD universe. There are also fics that focus on his relationships with the female characters in DxD, like how he would interact with Rias or Akeno, given his more reserved nature compared to the typical DxD male characters.
A plot could involve Shirou being transferred to the Highschool DxD school. He quickly catches the attention of Rias and her peerage. His different style of combat and his unwavering determination might lead to some friendly rivalries within the group. He could also introduce some new concepts of magic that the DxD characters have never seen before, like his ability to reinforce objects. And he may find himself in the middle of the power struggles between the different factions in this new world.
In fanfiction, Shirou Emiya could be integrated into the Highschool DxD world by being a wildcard factor. For example, he could be a human with powers that no one expected. His strong sense of justice would lead him to get involved in the conflicts between the different supernatural groups. He might even form his own group of allies, made up of both normal students and supernatural beings who believe in his cause.
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.
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.
His projection magic can be adjusted to work with the different types of magic in Highschool DxD. For example, it could be made more powerful by incorporating demonic or angelic energy sources.