One common theme could be the character's growth in self - confidence. In High School DxD, Rias is a strong character. Fanfiction might explore how a character feels embarrassed when naked at first, but then overcomes it and grows. For example, it could be a situation where a new character in the fanfic is accidentally exposed and has to deal with the humiliation, but through Rias' influence or the support of the group in the story, they learn to be more self - assured.
It can also be a turning point in the story. Maybe the character who is embarrassed naked decides to change something about themselves or their situation. This could lead to new character development arcs. For example, they might become more assertive in protecting their privacy or more open about their insecurities, which changes the direction of the fanfic's plot.
One possible fanfiction idea could be that Rias' sick brother is a key factor in a power struggle within their supernatural world. Naruto, being an outsider with his own set of skills and values, could get involved. Maybe he forms an alliance with Rias to protect her brother from those who would use his illness to their advantage.
They would likely start with some mutual curiosity. Naruto would be intrigued by Rias's devilish appearance and powers, while Rias would be interested in Naruto's ninja abilities. They might exchange stories about their respective worlds, with Naruto talking about his village and his friends, and Rias sharing about the devil society. Interaction could also involve sparring sessions to test each other's strength.
I don't have enough information to specifically say who Rias is in this fanfic. It could be an original character created by the fanfic author, or it could be a character borrowed from an existing series but given a new spin in the fanfic.
The plot could involve Naruto using his knowledge of chakra to diagnose Rias' brother's illness. He might discover that it's not a normal sickness but something related to the supernatural nature of their world. For example, his chakra flow could be disrupted by a dark magic spell.
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.
Popular Issei Rias lemon fanfics can be really hard to pin down. It depends on various factors such as the writing style, the plot development, and how well the characters are portrayed. Some fanfics might focus on their relationship development from a more emotional and psychological perspective, while others might be more about their adventures together with a touch of romance. You really have to dig through different sources to find ones that suit your taste.
Definitely. The concept of combining different fictional universes in fanfiction is quite common. In a 'Naruto is Rias' Familiar' fanfiction, we could expect to see Naruto's ninja skills and powers being incorporated into the world of High School DxD. Maybe Naruto would use his shadow clone jutsu in battles in the DxD universe or his rasengan against some of the devils. It could also explore how Naruto, with his strong sense of justice and loyalty, would interact with Rias and the other characters in her peerage.
In this fanfiction, Naruto might show his jealousy in his typical brash way. He could be all fired up and ready to challenge the person who is making him jealous. Rias, on the other hand, would be more calculating in her jealousy. She might use her devilish powers and influence to subtly drive a wedge between the person causing the jealousy and the object of her affection. They could end up teaming up to get rid of the 'competition' in a rather comical or intense way depending on the tone of the fanfiction.