You can try looking on fanfiction websites like FanFiction.net or Archive of Our Own (AO3). Just search for 'Issei and Ravel' in the search bar on those sites and then filter through the results to find ones that might include a kiss scene.
No. In the official Naruto and High School DxD universes, there's no relation between them. But in fanfic, the writer can make up any relationship they want. It might be for the sake of adding an interesting twist to the story, like bringing together the ninja world of Naruto and the devil - based world of High School DxD in a new family - centered way.
The story behind Ravel's Bolero is that it was an exploration of gradual musical development. Ravel wanted to create a piece that started simply and then blossomed into a rich and intense composition.
There could be a fanfiction where Naruto's chakra is somehow connected to a powerful magic source in Ravel's world. This connection causes chaos at first but then they figure out a way to use it to their advantage. Maybe they use it to restore balance in both their worlds that were being threatened by a common evil. They travel between the two worlds, gathering allies and knowledge along the way.
One great Oc x Ravel fanfiction is 'A New Bond'. It beautifully develops the relationship between the original character and Ravel in a fantasy - filled setting.
One possible fanfic could be about Ravel from Highschool DxD finding herself in the Naruto world. Maybe she could use her unique abilities, like her magic skills, to interact with the ninjas. For example, she might befriend Naruto and help him with a difficult mission using her magical powers to provide an unexpected advantage.
One common theme is the exploration of different powers. Naruto has his chakra - based ninjutsu while Ravel has her own set of abilities. Fanfictions often explore how these powers interact and complement each other. For example, Naruto's shadow clone jutsu could be combined with Ravel's magic in creative ways.
I really liked the fanfiction titled 'Ravel's Destiny'. In this one, Ravel discovers a hidden power within herself. The story has great plot twists and the author does an excellent job of keeping Ravel's personality true to the original while also adding new dimensions to her character.
One interesting 'Naruto Ravel DxD' fanfiction could be where Naruto somehow gets transported to the DxD universe and teams up with Ravel. In this type of story, they might face common enemies together. Maybe Naruto's unique jutsu and his never - give - up attitude would be a great asset in the DxD world filled with devils and other supernatural beings.
There are likely some out there. Some fans might write about Naruto and Ravel in a more platonic or adventure - based way. They could explore how the two characters from different universes might interact in a world where they meet, perhaps teaming up to face a common enemy or solve a mystery without any inappropriate undertones.