Sasuke from Naruto might be more cautious. He would see the mermaids as potential allies or threats. If they showed any sign of being a threat, he would be on guard. But if they proved to be helpful, he could work with them in a more strategic way. He might be interested in how their powers could be used in combat.
The mermaid characters from 'My Bride is a Mermaid' would likely be a bit intimidated by the ninja at first. The ninja's use of jutsu and their combat skills would seem very strange and powerful to them. But as they get to know each other, they could learn a great deal from one another. For instance, the mermaids could teach the ninja about underwater survival and the ninja could teach the mermaids some self - defense techniques.
Naruto would probably be very curious about the mermaids. He might try to befriend them immediately. His friendly and outgoing nature would make him eager to learn about their culture and abilities. For example, he would be amazed at how mermaids can swim so gracefully and control water in ways he's never seen before.
The Phantom could view the mermaids as ethereal beings with voices that are pure and untainted by the harshness of the human world. He might be envious yet inspired by them. Meanwhile, the mermaids could see the Phantom as a mysterious and somewhat frightening figure at first. But as they get to know his love for music, they might start to understand him.
Naruto, with his friendly and outgoing personality, would quickly befriend the DMC 5 characters. He would be eager to learn about their world and share his own ninja world experiences. He might even try to teach them some basic ninja techniques, like how to walk on water or climb trees.
Naruto would probably be very excited to meet the Agents of Shield. He'd be eager to show off his ninja skills and learn about their cool gadgets. He might even challenge them to a friendly sparring match. Meanwhile, agents like Coulson would be intrigued by Naruto's chakra and the whole ninja concept. They'd likely try to study it while also trying to figure out how to work with him. Characters like Sakura could offer her medical ninja skills to the team, which could be very useful in their missions.
Naruto himself would be very friendly and eager to help. He would probably be fascinated by Juliet's chainsaw and ask a lot of questions about it. He might even try to use it himself in a comical way at first. His positive attitude would likely boost the morale of the Lollipop Chainsaw characters.
Some of the Monster High characters could learn from the Naruto characters' discipline. Take Lagoona Blue for example, she could observe how the ninja train hard every day. And the Naruto characters might learn about the importance of being true to oneself from the Monster High students. Naruto could see how the monsters embrace their unique identities and be inspired to further promote acceptance in his own world.
Naruto might be really confused by the Bride of Chucky at first. He's used to dealing with ninja and other normal threats in his world. The Bride of Chucky, on the other hand, would see Naruto as a potential obstacle or a target. They could start off as enemies, with Naruto trying to protect his village from her.
Kakashi would be very observant. He'd be quickly analyzing the powers and social structures in The Highschool of DxD. He might take on a mentoring role for some of the younger characters in both worlds. If there were any conflicts, he'd use his wisdom and combat skills to try and resolve them. And he could also learn from the more experienced characters in The Highschool of DxD, like Sirzechs. This exchange of knowledge and skills between the two groups of characters could create a rich and engaging fanfiction story.
Naruto would probably be really friendly and curious. He'd be asking a lot of questions about the different species in Highschool DxD. He might try to make friends with Issei right away, seeing his determination. Sasuke, on the other hand, would be more aloof and might initially see the devils and angels as potential threats. The female characters from Naruto like Sakura would be interested in the female characters in Highschool DxD, comparing their skills and abilities.
The characters' interactions would be really interesting. For instance, Ford from Gravity Falls, being a scientist, would be fascinated by the magic in Equestria. He might try to find a scientific explanation for it. Fluttershy would be a bit shy around the Gravity Falls humans at first, but would soon open up. The ponies' positive and friendly nature might have an impact on the more cynical characters in Gravity Falls, like Soos. He could learn a lot from their friendship values. Meanwhile, the Gravity Falls gang could introduce the ponies to new things like s'mores and camping.
In a fanfiction, Naruto would likely be very curious about the Thundermans' superpowers. He might constantly ask them how they got their powers and if they could teach him. The Thundermans, on the other hand, would be fascinated by Naruto's ninja way. For example, Phoebe might admire Naruto's determination and sense of justice. They could start by being a bit wary of each other, but as they get to know one another, they would start to work together. Naruto could show them some of his cool ninja tricks, like walking on water, and the Thundermans could show Naruto how to use modern gadgets.