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.
One common theme is power and its consequences. Since Shirou has godlike powers in these fanfictions, it often explores how such great power affects him, whether it corrupts him or makes him a better person.
Another good choice would be Harry Potter. Imagine Shirou in the wizarding world. He could use his tracing ability to create magical items, and he could also learn new spells from the Hogwarts professors. They could team up to fight against dark wizards.
One popular Shirou Emiya crossover fanfiction could be where he crosses over with the Fate/Grand Order universe. In this, Shirou might interact with different Servants from the game in new and exciting storylines. Another could be a crossover with the Nasuverse in general, exploring his role in different settings within that vast fictional cosmos.
A great Shirou Emiya crossover fanfic is 'Shirou and the Avengers'. Imagine Shirou in the Marvel Universe. He could project Mjolnir and use Thor's power. His selfless nature would fit well with the Avengers' values. Also, 'Shirou in the Dragon Ball Universe' is fascinating. He might train with Goku and learn ki control, while also showing his own swordsmanship skills against powerful foes in that universe.
Well, it's very likely. Since Naruto and Shirou Emiya come from two different yet highly popular anime/manga universes. Fans love to create crossovers in fanfiction to see how characters from one world would interact in the context of another. Some of these fanfics might be really well - written and offer interesting takes on how Naruto could be like Shirou Emiya, perhaps in terms of their personalities, goals, or even their powers if some creative liberties are taken.
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.
I think 'Godlike Shirou's Grand Adventure' is a really good one. This fanfiction has Shirou with godlike powers in a crossover scenario. It starts with Shirou suddenly finding himself in a world full of different characters from other franchises. He has to use his newfound powers to not only survive but also to protect those he cares about. The story delves deep into his character, exploring how his power changes him and his relationships with others. It also has some really cool action scenes that are well - written.
One idea could be that Archer is transported to an alternate universe where Shirou has a completely different personality. Maybe Shirou is a villain in this world, and Archer has to figure out how to deal with him. Another plot could involve them teaming up to fight a powerful, new enemy that neither could defeat alone. For example, a powerful mage from a different dimension who wants to conquer their world.
Another plot could involve Shirou reincarnated in a modern superhero world. He might struggle to fit in at first, but then realizes his abilities can be used to fight super - villains. His noble phantasm could be adapted in a unique way to combat the new threats in this world.