A possible fanfiction plot could be that Gremory and Gabriel are sent on a mission to the Naruto universe. They have to blend in and find a way to work with Naruto to stop a group of rogue ninjas who have somehow obtained dark magic from the demon world. Naruto is skeptical at first but then realizes that Gremory and Gabriel have skills and knowledge that can help him protect his village. Together, they train and share their powers and techniques to face this new threat.
Maybe in the fanfiction, Naruto is summoned to the world of Gremory and Gabriel by a powerful magic. He is initially confused but quickly adapts. Gremory could be intrigued by Naruto's unique abilities and his never - give - up attitude. Gabriel, on the other hand, might be a bit more cautious at first. But as they get to know Naruto better, they all work together to solve a mystery that has been plaguing their world, like the disappearance of a powerful magical artifact that holds the key to maintaining peace.
One idea could be a crossover where Naruto's world is merged with the one that Gremory and Gabriel exist in. Naruto, with his strong will and ninja skills, could form an alliance with Gremory, who might be from a noble demon family, and Gabriel, an angel. They could fight against a common enemy that threatens both their realms, like a powerful dark force that wants to disrupt the balance between the ninja world, the demon world, and the angelic realm.
For Naruto, his development could focus on how he adapts to a new world with different rules and powers. He might start by being a bit naive about the ways of Gremory and Gabriel's world but quickly learn. His ninja skills could also be enhanced or modified as he combines them with the magic or powers he encounters. Gremory could develop by becoming more open - minded. Maybe she starts off with a certain view of humans (since Naruto is human) but through her interactions with him, she changes. Gabriel could develop in terms of his relationship with non - angelic beings. He might start off as distant but as he gets to know Naruto, he becomes more involved in the affairs of other worlds.
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 possibility is that Clayface somehow gets transported to the Naruto universe. The shinobi in the Naruto world would be very confused by his abilities. Clayface could try to blend in by mimicking the appearance of different shinobi, but his lack of chakra would give him away. Naruto might see through his disguise easily due to his own perceptive skills.
One idea could be a crossover where Naruto is transported to Noire's world. He could use his ninja skills to help Noire in her battles against the various threats in her realm. For example, Naruto's shadow clone jutsu could be used to confuse the enemies while Noire attacks from a different angle.
One idea could be a crossover where Naruto and his friends are transported to the Soul Society. Naruto's positive attitude and determination might inspire the Soul Reapers in a new way. He could learn some of their techniques, and in return, teach them about chakra and his own ninja skills.
A possible fanfiction plot is that Naruto has a strange dream about a powerful being named Yubel. Intrigued, he sets out on a journey to find out more about her. Along the way, he meets different characters who either know about Yubel or have some connection to the power she wields. This journey changes Naruto in ways he didn't expect, and he eventually finds a way to communicate with Yubel across different dimensions.
One idea could be a crossover where Naruto, with his ninja skills, is transported to Celty's world. He might team up with Celty to solve some mystery in her city. Naruto's ability to sense danger and Celty's unique skills could make for an interesting partnership.
A more comical fanfiction could be about Kale trying to adapt to the food in the Naruto world. Naruto could introduce her to ramen, and she might have some really funny reactions, while also sharing some Saiyan cuisine with Naruto and his friends.
One idea could be a story where Naruto somehow gains the ability to use Susanoo. Maybe through some strange chakra experiment gone wrong or a gift from an ancient entity. He then has to learn how to control this new power while still maintaining his own ninja way.
One idea could be a crossover where Naruto is transported to Sindel's world. He might use his ninja skills to survive in the new and dangerous environment. For example, his ability to move quickly and stealthily could help him avoid the threats in Sindel's realm.