The story could develop with Issei forming his own group. He might gather other characters who also feel left out or have similar goals. This new group could then become a rival to Rias' peerage, leading to interesting battles and power plays.
One possible reason could be a desire for self - discovery. Issei might feel that being in Rias' peerage limits his growth in certain ways. He may want to explore his powers and identity on his own terms.
The dynamic within Rias' peerage would be greatly affected. There would be a power vacuum as Naruto is likely a strong member. His departure might cause some members to question Rias' leadership. Maybe they start to worry that if she couldn't keep Naruto, who else might leave? Also, in battles, they would have to find new strategies without Naruto's unique abilities.
If Issei leaves Rias, the power dynamics in the story would shift drastically. Rias's peerage would be weakened without Issei's strength. Also, Issei would have to find his own place in the devil world. He might explore other areas of the supernatural and form new relationships.
The pregnancy in the fanfiction could also bring about a new era for their group. It could be a symbol of hope and new beginnings. Issei and Rias' relationship could become an example for other characters. The story could explore how they prepare for the baby, like setting up a nursery in their supernatural abode. There might be a time when Rias' powers are affected by the pregnancy, and Issei has to step up even more to protect her. And as the due date approaches, the excitement and nervousness among the entire group would be palpable.
One idea could be that Issei leaves Rias because he realizes he has different goals in the supernatural world. He might want to focus on helping the weaker devils rather than being part of Rias's peerage. So he sets out on his own journey, making new allies and facing new challenges.
His character might become more adaptable. In Rias's peerage, he'd face different challenges and cultures compared to the wizarding world. So he'd have to learn new ways to interact and fight.
Well, one possibility is that Naruto's unique skills and his never - give - up attitude would make him a great asset to Rias' peerage. His shadow clone jutsu could be used in various strategic ways during battles. For example, he could send clones to scout the area while the main group plans their attack. His rasengan could also be a powerful offensive move against their enemies. And his ability to make friends easily might also help in building stronger bonds within the peerage.
It would likely have a huge impact on the plot. New alliances might form around protecting the baby. Enemies could see the baby as a threat or a valuable asset. The story could shift from their individual adventures to more family - focused ones.
Naruto's powers could complement the members of Rias' peerage. For example, his speed could assist in quickly getting into position during battles, which would work well with the more long - range or support - based abilities of some peerage members.
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.