What are some interesting ideas for a High School DxD fanfiction?

A third concept could be a killer who was once a victim of the dark side of the High School DxD universe. They now seek revenge on those who wronged them. However, as the story progresses, they realize that revenge is not the answer and end up joining forces with the good guys to make the world a better place.

One idea could be to explore a new character reincarnating into the High School DxD world with a unique power, like the ability to control time in small bursts. This could lead to some really interesting plot twists, such as being able to freeze time during battles or rewind to correct mistakes. Another idea is to have a reincarnated character who has memories of a different type of mythology and tries to incorporate that knowledge into the existing world of High School DxD. For example, if they remember Norse mythology, they could introduce new spells or artifacts related to it. A third idea is to focus on a reincarnated character who is trying to change the fates of some of the main characters. Maybe they know how things are supposed to play out from their past life knowledge and want to make things better for their favorite characters.

One idea could be Livia forming an unexpected alliance with a character like Issei. Maybe she has some unique knowledge about the supernatural world that she shares with him to help in a difficult situation.

You could do a crossover with 'Sword Art Online'. The virtual reality aspect of SAO could be combined with the supernatural elements of High School DxD. For example, the characters could be trapped in a virtual world that has elements of both worlds, and they have to fight their way out. Issei might have to use his skills in a new digital environment while also dealing with SAO - like challenges.

There could be a fanfiction where Sasuke's Sharingan has an unexpected interaction with the supernatural elements in High School DxD. For example, his ability to see through illusions could be enhanced or altered by the magic in that world. This could lead to him having a different role in the battles and relationships within the High School DxD setting.

One idea could be exploring the backstory of an exorcist character in more depth. Maybe they have a hidden past related to the devils in High School DxD that no one else knows about.

A plot could involve Kaido being sent on a special mission by the Devil King to infiltrate a human school. During this, he starts to develop real friendships with the characters in High School DxD. His initial motives are questioned as he begins to care more about his new friends than his mission, creating a lot of internal conflict.

One idea could be a Dragonborn character arriving in the High School DxD world and having to adapt to the unique school and supernatural environment. They might use their dragonborn abilities to stand out in the Rating Games.

One plot idea could be that Naruto is summoned to the High School DxD world by a powerful magic user who mistakes him for a powerful demon. Once there, Naruto has to prove that he is not a threat while also trying to find a way back home. Along the way, he befriends some of the students at the school and helps them with their own problems, like protecting the school from a sudden attack by a group of rogue devils.

Well, a cool crossover idea might be the sharing of powers. Imagine if some of the High School DxD characters could learn Naruto's shadow clone jutsu. It would be really useful in battles. Also, the idea of Naruto characters trying to understand the complex social hierarchy in DxD could be very entertaining. They could end up forming alliances in unexpected ways, like the ninjas teaming up with the devils to fight against a powerful demon from Naruto's world that has somehow entered the DxD realm.