One possible fanfiction could be about a crossover where the characters from Highschool DxD and Naruto are transported to a world where they meet Gabriel. Maybe they team up to fight a common enemy. For example, the devils from Highschool DxD and the ninjas from Naruto could combine their powers under Gabriel's guidance to defeat an ancient evil that threatens all three of their realms.
Another way her character develops is through her own self - discovery. Fanfictions often explore Gabriel's identity as an angel in a new light. She might question some of the strict rules and dogmas of the angelic realm. This internal struggle can lead to her evolving into a more complex and independent character. She may start to make decisions based on her own beliefs and values rather than just following what she was taught as an angel, which is a significant step in her character development.
One popular storyline could be Gabriel's interaction with the main characters from Highschool DxD in a more peaceful school setting. For example, she might be involved in a friendly competition among the different factions at the school. Another could be a story where Gabriel has to adapt to the modern human world while still maintaining her angelic duties. She could face challenges like understanding modern technology or human emotions.
You can try fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Highschool DxD Issei x Gabriel' on their search bars, and you should be able to find relevant fanfictions.
One interesting crossover could be a story where the power - up systems from Highschool DxD and Naruto are combined. For example, the devils in Highschool DxD could learn chakra control from Naruto characters. As for Gabriel, she could be a mediator between the two very different universes. Maybe she uses her angelic powers to help the characters understand each other's worlds.
One possible plot could be that Naruto is somehow transported to the Highschool DxD universe and meets Gabriel. They might team up to face a common threat that is endangering both the ninja world and the supernatural world of Highschool DxD. Naruto's unique skills as a ninja could be combined with Gabriel's angelic powers in an epic battle against evil forces.
One way to combine them could be in a crossover universe. For example, Naruto could be summoned to the world of Highschool DxD through some sort of magical mishap. Gabriel, being an angel in her own right, could be involved in a plot to either help Naruto return home or to use his power for some greater purpose in the Highschool DxD world. Maybe Naruto's unique abilities, like his shadow clones or rasengan, could be seen as strange and powerful in the DxD world, and Gabriel might have insights on how to control or enhance them.
Well, the plot could involve Harry being a new transfer student to the Highschool DxD world and Gabriel being one of the first to befriend him. Maybe they team up to face some of the common threats in that universe, like the devils or fallen angels. They could also explore their own unique powers together and learn from each other.
The fanfictions also allow for a deeper exploration of the characters' personalities. Issei's determination and Gabriel's grace can be further developed. Writers might give them new backstories or put them in situations that are not in the original anime. This gives readers a fresh perspective on the characters and their relationship, which is what makes these fanfictions so interesting.
They could interact in a training - centered story. Naruto characters could teach Highschool DxD characters about chakra and physical conditioning. Gabriel could then introduce her own form of spiritual training. In return, Highschool DxD characters could show the others about their unique magical items and powers. This exchange of knowledge and skills would create interesting dynamics among the characters from these three different universes.