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

A great idea for a High School DxD fanfiction is to explore a romantic relationship that is not the typical one in the series. For instance, a story about a relationship between two side characters who have to overcome many obstacles due to their different species or social status within the devil - angel - fallen angel hierarchy. You could also write about a character's journey of self - discovery outside of the main plot of the series. Like a character who realizes they have a different purpose in life than what they were initially led to believe.

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.

Well, in 'high school dxd torture fanfiction', a plot could involve a character being physically tortured in a magical prison where the pain is amplified by dark magic. This could lead to the character having to find inner strength and allies to escape. Also, perhaps a character is tortured by being isolated from their friends and loved ones, which is a form of emotional torture.

A plot could revolve around a mystery in Akatsuki High School. There could be a series of strange events happening, like students disappearing or strange symbols appearing. The DxD characters would then have to use their skills and knowledge to solve the mystery, which could lead to uncovering a dark secret about the school's past.

A plot idea could be that some of the devils in High School DxD want to learn the secrets of chakra from Naruto. So they kidnap him to their world. Naruto then has to find a way to escape while also dealing with the political intrigue among the devils, angels, and fallen angels. Another idea is that Naruto's shadow clones could be mistaken for some new type of summoned creatures in the DxD world.

Another plot could involve a time - travel scenario. Maybe a character accidentally sends themselves and some of their friends back in time to when the first devils were created. They would have to navigate this ancient world while also trying not to change history too much, or else it could have dire consequences for their present.