One interesting concept could be the fusion of Naruto's ninja abilities with the supernatural elements from High School DxD. For example, imagine Naruto using his shadow clone jutsu in the middle of a devil - angel battle in the DxD universe. It would add a whole new dynamic to the battles there.
One interesting concept could be the combination of different power systems. For example, how the ninjutsu from Naruto might interact with the magic in DxD. Maybe a character could use shadow clones to perform a complex magic spell simultaneously. Another concept could be the crossovers of characters. Picture Naruto characters in the DxD world, like Naruto himself being in the middle of a devil - angel - fallen angel conflict. It could lead to really unique story developments.
One interesting concept could be alternative character backstories. For example, a fanfiction might explore what led a side character to become an agent. Another concept could be different rankings systems within the Border organization. It could also be about new types of Triggers that are created by the characters in the fanfiction.
One interesting concept could be the combination of Naruto's ninja abilities with the supernatural elements from Highschool DxD. For example, Naruto's shadow clone jutsu might be used in a creative way in the Highschool DxD setting, like having clones help out in battles against devils or angels. Another concept could be the character interactions. If characters from Naruto like Naruto himself or Sasuke were to interact with the characters from Highschool DxD such as Issei, there would be a lot of cultural and power - based clashes and exchanges. It could also be interesting to see how the different power systems mesh together, like chakra and the sacred gears in Highschool DxD.
One interesting concept could be Naruto's unique jutsu in the Highschool DxD world. For example, his shadow clone jutsu could be used in battles against the devils or fallen angels in the Highschool DxD universe. Another concept might be how Naruto's ninja values of loyalty and hard work would influence the characters in Highschool DxD. Maybe he'd form an unlikely alliance with some of the factions based on his strong moral code.
One interesting concept could be the combination of different characters' abilities from the original Black Trigger universe in new and unexpected ways. For example, seeing how a character with a speed - based Black Trigger might team up with a power - based one in a crossover scenario.
In this fanfic, the power - up concepts can be very interesting. Since both Naruto and DxD have different power systems. A character might gain new powers by combining the chakra system with the sacred gears in DxD. This could lead to unique abilities that we haven't seen in either of the original stories, like a sage - mode enhanced by a sacred gear's power.
One interesting concept could be the fusion of the Naruto and High School DxD universes. For example, seeing how Naruto's ninja skills would interact with the devil - based powers in DxD. Maybe Naruto characters using their chakra in the DxD world to fight against devils or angels in new and unexpected ways.
One interesting concept is the exploration of different devil peerages. Fanfiction often delves deeper into the relationships between the devils and their servants. Another is the alternate storylines for the main characters. For example, a fanfic might have Issei developing new powers earlier or taking a different path in his relationships. Also, the creation of new characters that fit seamlessly into the Vampires DxD universe can be really engaging.
One interesting concept could be the re - imagining of character relationships. For example, how the different devil clans interact in new and unexpected ways. Another might be the exploration of new magical abilities that are not in the original series but are created within the fanfiction world. Also, some fanfictions might focus on a different take on the Rating Game, making it more strategic or having different rules.
Some interesting crossover concepts could involve the love interests. In Highschool DxD, there are a lot of complex relationships. If we introduce Naruto characters into this, it could create some really interesting love triangles or other relationship dynamics. For instance, what if Hinata had a crush on Issei? Or if Rias was interested in Naruto? This would not only add a new layer of drama but also force the characters to navigate through different cultural and power - based expectations in their relationships.