Maybe a plot where the main character from the original High School DxD gets sent to an alternate dimension in the Devil Reborn Redux fanfiction world. In this dimension, the rules are slightly different, and he has to adapt quickly. He might find that some of his friends are now enemies and vice versa, and he has to figure out how to get back to his own dimension while also dealing with the new threats and challenges there.
One interesting plot idea could be a new character introduced in the fanfiction who has a unique power that disrupts the power balance in the High School DxD world. For example, a devil with the ability to nullify all other devil powers temporarily. This could lead to a lot of interesting conflicts and alliances as different factions try to either use or get rid of this new character.
One idea could be a new devil character arriving at Kuoh Academy with a unique power that challenges the existing power dynamics among the devils there. For example, a devil who can manipulate time in small increments during battles, which would make for some really intense and strategic fight scenes.
Issei Hyoudou is often still a very popular character. His journey as a devil and his growth in power are central to the High School DxD series, and in the Devil Reborn Redux fanfiction, fans usually enjoy seeing his further development. He might face new challenges and relationships that keep his character engaging.
One idea could be a story where the main character, a human, discovers a unique power that allows them to hold their own against devils in the 'Highschool DxD' universe. They use this power to protect their school from devil threats that the regular characters might not be able to handle easily.
One idea could be an OC Devil who has a unique power related to time manipulation. For example, they can freeze time briefly in battles, giving them an edge. Another could be an OC Devil from a long - lost noble family trying to reclaim their family's honor and status within the Devil society. They would have to face many challenges and rivalries along the way.
One idea could be exploring a new power that the third devil discovers. For example, a unique ability to manipulate time on a small scale during battles, which would add a whole new dimension to the fight scenes. Another idea is to focus on the third devil's relationships with other characters in a different way. Maybe the third devil forms an unexpected alliance with a group that was previously an enemy, leading to some really interesting character development and plot twists.
A plot could also focus on a new character who is a hybrid of the two universes. They have the powers of both a devil from High School DxD and a wizard from Harry Potter. They struggle to find their place in either world as they are too different from the norm in both, and they embark on a journey to create their own identity and purpose.
One idea could be exploring new power-ups for the characters. For example, Issei could discover a hidden ability within his Boosted Gear that allows him to time - travel briefly during battles, adding a new strategic element. Another could be focusing on the relationships in the future. Maybe Rias and Issei have a family and the story could revolve around their children's upbringing in the supernatural world.
One idea could be a new character joining the school who has a unique supernatural ability that no one has seen before. This could disrupt the existing power dynamics and create all sorts of interesting interactions and challenges.
One idea could be to have a new character enter the world of Highschool DxD who challenges the existing power hierarchy and calls out the flaws in the main characters' actions. For example, this new character might see Issei's pervy ways as not just a comical trait but something that is disrespectful to the female characters and start a movement to change the way things are done in the school.
Well, perhaps a fanfiction where Griselda gets transported to a different dimension. In this new place, she has to adapt quickly and find a way back home. Along the way, she meets new allies and enemies. This would be a great way to explore her character in a different setting.