Naruto could bring a lot of energy and a new fighting style. His ninja skills would be a unique addition. For example, his shadow clone jutsu could be used for various strategic purposes in battles against other peerages. His positive and determined attitude would also be contagious, inspiring Rias' other servants to be more bold and confident.
Well, it would be quite an interesting relationship. Naruto's strong will and combat skills from his own world could mesh well with Rias' leadership in the Highschool DxD universe. He would likely bring a new sense of loyalty and determination to her peerage. Also, his ability to make friends easily might help him fit into the complex social structure of the DxD world.
In a Naruto - Rias' peerage fanfiction, the story might focus on how Naruto's chakra system interacts with the devil's power. For example, his ability to sense chakra could be enhanced or changed when combined with devilish senses. Also, his relationship with the members of the peerage would be interesting. He could form strong bonds with some, like Kiba in Naruto's world, he might get along well with the werewolf in Rias' peerage.
He might react with hostility. Dark Naruto has a certain edge to him, and if he sees Rias as a threat or someone he doesn't like, he'll likely oppose her. He could use his combat skills to challenge her directly.
In fanfiction, such a betrayal could occur due to power struggles. Maybe Rias sees Naruto as a threat to her position in the Highschool DxD world. She might fear his growing power and influence, which could overshadow her own. So, in order to maintain her status, she betrays him.
Well, in such a fanfiction, Dark Naruto might use his powerful and often shadowy abilities to outwit Rias. Maybe he'd expose some of her less - than - noble actions in the Highschool DxD world. He could easily overpower her in battles, using his ninja skills and the dark powers he has. For example, his shadow clones could be used to confuse Rias and her peerage while he strikes from the shadows.
Well, it could involve Naruto characters being thrown into the Highschool DxD universe and having some sort of conflict with Rias. Maybe Naruto's skills and values clash with Rias's actions or leadership in the story. For example, Naruto might see her as too power - hungry or not treating her underlings fairly.
A possible way for their worlds to merge in fanfiction is through a reincarnation plot. What if some of the Naruto characters were reincarnated in the Highschool DxD world? Naruto himself could be reborn as a devil or an angel. This would completely change the power balance and relationships in the Highschool DxD world. Rias would have to deal with this new Naruto, who still has his ninja spirit but now has to adapt to the rules and powers of the new world.
Naruto in Rias' peerage would be quite a sight. His orange jumpsuit would stand out among the devils. He might use his shadow clones to do multiple tasks within the peerage, like scouting or helping with household chores. His positive attitude would also have an impact on the often - serious devils in the peerage.
One great fanfiction idea could be that Issei discovers a new power within himself that is directly linked to Rias's heritage. Maybe he can tap into an ancient magic that only works in harmony with Rias's own powers. As they train together to master this new ability, their relationship deepens beyond just the typical master - servant bond in the Highschool DxD world.
A common theme is power - up. Rias may gain new powers or improve her existing ones. This could be related to her devil heritage or through some special training or encounter.