The fanfiction could blend the two worlds by having Naruto introduce new combat techniques to the High School DxD characters. This would make him seem even more attractive in the eyes of the potential harem members. Also, the story could explore how the values of the two worlds, like loyalty in Naruto's world and the complex power dynamics in High School DxD, play out when Naruto is at the center of a mass harem. Maybe the different races in High School DxD, such as devils, angels, and fallen angels, would all be interested in Naruto for different reasons related to his world and his abilities.
One way is through the power systems. Naruto's chakra could interact with the magic and powers in High School DxD. For instance, a character from High School DxD might be fascinated by Naruto's ability to use chakra and it could be a starting point for a relationship in the mass harem. Another aspect could be the cultures. The shinobi culture of Naruto's world is very different from the high school and supernatural culture of High School DxD. This contrast could create interesting situations in the fanfiction.
One way would be through power systems. Naruto's chakra could be related to the magic or power in High School DxD. The fox yokai part could be used to explain some of the more mysterious powers. For example, Naruto's fox - like speed and strength could be seen as yokai - like abilities in the High School DxD world.
Typically, they use some sort of magical or dimensional rift to merge the two worlds. For example, Naruto could be sucked into a portal that leads him to the High School DxD universe. Or, it could be a more complex plot device like a powerful villain trying to combine the two worlds for their own gain.
One way is through the power system. The Susanoo's power could be compared or combined with the powers in Highschool DxD. Naruto could bring his ninja way of thinking into the Highschool DxD world. For instance, his idea of never giving up could inspire the Highschool DxD characters. And in terms of the world - building, the fanfic could have Naruto's world of ninjas and the Highschool DxD's world of demons and angels co - exist. The Susanoo could be seen as a new and fearsome power in the Highschool DxD world.
Well, it could be about Naruto somehow being transported to the world of High School DxD. In this fanfic, he might end up in a situation where he attracts a large number of characters from both universes, forming a mass harem. Maybe his ninja skills and unique personality would be the reasons for all the attention. For example, his determination and ability to protect others could make him appealing to the female characters in High School DxD.
Well, one way it could blend is by having Naruto's ninja skills incorporated into the High School DxD world. Maybe Naruto could use his shadow clone jutsu to create diversions during the Rating Games in DxD. The Ten Tails' power could be a major plot device, like a powerful force that both sides in DxD are trying to either control or prevent from being controlled. For example, some of the devils in DxD might see the Ten Tails as a way to gain ultimate power over the other factions.
The orphan could rely on their adaptability. Since they are used to being alone, they might be more open to learning the new rules of both worlds. In the Naruto world, they might have learned to be resourceful, and they can apply that in High School DxD. For example, using their knowledge of chakra to understand and maybe even manipulate the magic in High School DxD.
Another way to blend the cultures is through their forms of combat. The ninja way of fighting in Naruto, with its emphasis on stealth, agility, and various jutsu, can be compared and contrasted with the more brute - force and magical combat in High School DxD. Characters could learn from each other, like a devil learning Naruto's shadow clone jutsu and using it in their battles. This would not only blend the combat cultures but also create new and exciting battle scenarios.
In a Naruto - Vikings crossover fanfiction, the power systems could be really interesting to combine. The Vikings have their physical strength and combat skills, while the ninja in Naruto have chakra and jutsu. Maybe a Viking could be exposed to chakra and start to develop their own unique form of jutsu based on their Viking heritage. For instance, a Viking with a connection to Thor could use lightning - based jutsu in a way that's different from how a normal Naruto character would. This would create a whole new dynamic in the story as the Vikings and Naruto characters learn from each other's powers.
A possible way to blend the two in a fanfiction would be through the power systems. In Naruto, there's chakra, and in Soul Eater, there are souls and soul wavelengths. The fanfiction could create a connection where chakra is related to the strength or quality of a character's soul. So Naruto characters with high - level chakra like Naruto and Sasuke would have very powerful souls in the Soul Eater world. Also, the different jutsu in Naruto could be adapted to deal with soul - related problems in the Soul Eater world, like using Fire Style jutsu to burn away corrupted souls.
The characters would have interesting interactions. Naruto, being the energetic and friendly hero, would likely make friends quickly in the Demon Slayer world. He'd probably be fascinated by the swords and the concept of demon slaying. And the Demon Slayer characters would be intrigued by Naruto's shadow clones and other jutsus. They could learn from each other and develop new strategies for fighting enemies. For example, Naruto could show them how to use mass - produced clones for distraction while the Demon Slayers attack from a different angle.