Obviously Naruto is one of the main characters. And of course, the Ice God Slayer would be a main character as well. There might also be characters like Sasuke who could get involved, either as an ally or an antagonist depending on the plot.
Well, a really interesting plot idea might be that the Ice God Slayer comes from a different dimension where ice is the main source of power. In the Naruto world, they have to adapt to chakra. So, the story could be about how they balance their ice god slaying powers with chakra. Maybe there's a villain who wants to steal the Ice God Slayer's power to control both ice and chakra, and Naruto has to help stop this. Also, the Ice God Slayer could have a special bond with an ice - based creature in the Naruto world, like a rare ice fox, and they go on adventures together with Naruto.
One idea could be that Naruto discovers a hidden power within himself that is related to God Slayer Magic. This new power could change the way he battles enemies in the Naruto universe. For example, he might be able to use it against powerful foes like Madara or Kaguya, giving him an edge he didn't have before.
Sasuke would be really interesting. He already has a dark and brooding nature. Adding Ice Devil Slayer powers would enhance his cool and aloof demeanor. He could use the ice powers in combination with his Sharingan and fire - based jutsu in really unique ways. For example, he could freeze the water created by a water - style jutsu and then shatter it with his ice powers.
In a Naruto learns God Slayer magic fanfiction, it could be really exciting. Naruto's already powerful ninja skills combined with God Slayer magic would make him an even more formidable force. He could use the magic in battles against tough enemies like Akatsuki members. Maybe he'd learn it from a mysterious character who travels between different dimensions, and this new power would give him an edge in protecting the Hidden Leaf Village.
It's also likely that Naruto becomes a god dragon slayer as a result of a prophecy. The fanfiction could explore how he initially struggles with this new role. He has to deal with the expectations that come with being a 'god' - level dragon slayer. Along the way, he might make new allies, like other dragon slayers or magical creatures who recognize his potential and help him in his journey to master this new power.
A possible fanfiction could involve Naruto's ninja skills combined with the God Slayer magic from its respective series and the magic of Fairy Tail. For example, Naruto could team up with Natsu from Fairy Tail and a God Slayer character to take on a powerful enemy that threatens all three of their worlds. They would each bring their unique abilities to the fight, like Naruto's shadow clones, Natsu's fire magic, and the God Slayer's divine - based powers.
It could be an evil ice mage who wants to use the Ice God Slayer's power to freeze the entire world. This mage might have a tragic past that led them to believe that freezing the world is the only way to create peace.
One popular plotline could be the Ice Dragon Slayer character from a different world ending up in the Naruto universe. They might have to adapt to the ninja world while also using their ice dragon slaying abilities in unique ways, like fighting the Akatsuki. Another could be the Ice Dragon Slayer training Naruto or some of the other ninja in ice - based techniques, which would be a new and interesting addition to the existing jutsu in the Naruto world. And sometimes, there's a plotline where the Ice Dragon Slayer has a hidden past related to an ancient clan in the Naruto universe that gives them special powers or a mission to fulfill.
The main villain could be an ice demon with the power to manipulate time. It freezes entire villages in different time loops, causing chaos. Naruto and the demon slayers must figure out how to break the time - frozen spells and defeat this powerful demon. The demon could also have the ability to create illusions, making it even harder for the heroes to fight it.