In this fanfiction, an interesting idea is the customization of Personas by the Highschool DxD characters. Since in Persona games, you can customize and evolve your Personas, it would be exciting to see how the characters in Highschool DxD would do the same. Maybe they would use their devil powers or unique skills to modify their Personas, creating really powerful and unique combinations for battles and challenges.
The adaptation of gaming mechanics into the Highschool DxD world is also really cool. The SI OC might introduce things like RPG - style leveling systems for the characters in the story. So instead of just the normal power - ups in the original series, characters could gain experience points and level up, unlocking new skills and abilities, which would change the power dynamics and the overall flow of the story.
In 'Highschool DxD Fate Op Gamer Fanfiction', a really cool concept could be how the 'Fate' system of contracts and magic meshes with the devil - angel - fallen angel dynamic of 'Highschool DxD'. For example, a character could use 'Fate' magic to form new contracts with other beings. The 'op' nature of some elements might lead to unexpected alliances or rivalries. The 'gamer' aspect could also add a strategic layer, like characters having to manage resources or build up their stats in order to succeed in battles or challenges within the story.
In 'Persona 3 and Highschool DxD fanfiction', a cool crossover might involve the social links in Persona 3 being related to the relationships in Highschool DxD. For instance, the friendship between the characters in Persona 3 could be paralleled with the bonds of loyalty among the devils in Highschool DxD. Also, the Velvet Room in Persona 3 could have some sort of connection to the magic and power systems in Highschool DxD. It could be that the Velvet Room attendant has some knowledge about the devil fruits or the sacred gears in Highschool DxD.
Issei is often a very popular character. His pervy nature and his growth as a character in the original Highschool DxD series make him stand out. In the fanfiction with Persona and gamer elements, his ability to adapt to new powers and situations can be really interesting to explore.
Another idea in the crossovers could be the exchange of technology or magic. The Velvet Room from Persona might have some connection to the magic system in Highschool DxD. Maybe the Velvet Room attendant could offer some insights or tools to the characters in Highschool DxD, like a special artifact that helps in controlling their powers better.
In some Highschool DxD SI Fanfiction, the self - insert might come from a different world or time period. This brings in elements of cultural shock and different knowledge systems. They could introduce new technologies or fighting styles to the world of Highschool DxD, which can lead to very creative and engaging storylines.
One interesting concept could be the combination of Pokemon powers with the abilities of the characters in Highschool DxD. For example, a character might be able to use a Pikachu's electricity - based attacks in combat situations within the Highschool DxD universe. Another concept could be the idea of Pokemon existing in the same world as the devils, angels, and fallen angels in Highschool DxD. This could lead to some really unique interactions, like a Pokemon being tamed by a devil and used as a sort of familiar or ally in battles against other factions.
Another concept could be the exploration of different power systems. Hellsing has its own set of rules regarding vampire powers, holy weapons, etc., while Highschool DxD has the Rating Game system and the various devil powers. Fanfiction might play around with how these power systems interact, like if a character from Hellsing were to participate in a Rating Game or how a devil from Highschool DxD would fare against a Hellsing vampire.
One interesting concept could be the exploration of different character relationships in a more subdued or 'silent' way. For example, how the main character might form unexpected friendships without the typical high - energy drama. Another could be the re - imagining of the story's settings in a more peaceful or reflective manner.
In Aizen Highschool DxD fanfiction, a cool concept might be how Aizen's Zanpakuto abilities would translate in the Highschool DxD setting. His Shikai and Bankai could have new and unexpected effects. Maybe his illusions could be used to deceive not just in battle, but also in the social and political intrigue that is so common in the Highschool DxD world among the different factions.