Well, it could be about their eternal struggle in a new light. Maybe in a world where they have to team up against a greater threat. For example, a new powerful Pokemon that is causing chaos in their shared ecosystem. Their powers combined could create a unique dynamic.
The fanfic might explore their relationship in a more emotional way. Groudon could be portrayed as a hot - tempered but noble being, while Kyogre as a calm yet powerful force. They could start to understand each other's motives and develop a mutual respect. This could lead to them finding a balance between land and sea, which is different from their traditional rivalry.
In a Groudon x Kyogre fanfic, the story could be set in a post - apocalyptic world where their battle has already wreaked havoc. Survivors might be trying to get Groudon and Kyogre to reconcile. The fanfic could then focus on the journey of these survivors as they try to communicate with the two titans and make them see the need for peace. This would involve a lot of world - building and character development for the humans involved as well as exploring the complex personalities of Groudon and Kyogre.
For Kyogre, it could be characterized as a powerful but somewhat solitary being. It's protective of the oceans and views any threat to the seas as a direct attack. It's majestic and its movements are fluid like the waves. Groudon, on the other hand, is a force of the land. It's stubborn and proud, believing that the land is the most important part of the world. It's slow to trust but once it does, it's a loyal ally.
In a fanfic, Groudon can be seen as a proud and territorial being. Since it represents the land, it guards its territory fiercely. It has a sense of honor and dignity associated with its role as the keeper of the earth. Kyogre can be characterized as a wise and ancient entity. It has seen the ebb and flow of countless years beneath the ocean waves. It is patient but when provoked, it can call upon the power of the entire ocean to defend itself. They both can be shown as having a mutual respect for each other's power deep down, even though their natures often put them at odds.
One popular 'kyogre x groudon fanfic' is 'The Clash of Titans'. It really delves into the relationship between Kyogre and Groudon in a unique way. The story sets up an interesting scenario where they have to work together despite their natural enmity. It's full of action and also some great character development.
The potential for unique relationships. They can be rivals, but also in some fanfics, they become friends or even more. Their relationship can be explored in many different ways, like in some fanfics where they learn to understand each other's importance in the Pokémon ecosystem.
I'm not sure specifically as I haven't read that exact fanfic. But generally, a fanfic about Groudon and Kyogre might explore their relationship in the Pokemon universe. It could be about their battles, their coexistence, or some fictional scenarios where they interact in unique ways.
To develop Groudon's character, you could focus on its fiery nature. Show how it's not just about destruction but also about the renewal of the land. For Kyogre, emphasize its connection to the vastness of the ocean and its role in maintaining the balance of marine life. You could give them internal thoughts, like Groudon might be frustrated with always being seen as the one causing droughts, and Kyogre with being blamed for floods.
One idea could be that Groudon and Kyogre are forced to team up against a new, greater threat that endangers the entire Pokemon world. This could be a powerful, ancient Pokemon that has been awakened. Another plot could be a story where a trainer tries to understand the relationship between Groudon and Kyogre through a series of dreams and adventures, and in the process, discovers a hidden power that lies within their connection.
You can try looking on fanfic websites like FanFiction.net or Archive of Our Own. They have a large collection of Pokemon - related fanfics, so there's a chance you might find it there.
A plot could also revolve around a new type of power - enhancing crystal that has been discovered. Kyogre and Groudon both want it to boost their own strength. A group of trainers get caught in the middle of their struggle. They have to figure out a way to either stop the two Legendary Pokemon from fighting over it or find a way to share the crystal's power between them to maintain the balance in the world.
One interesting plot idea could be that Groudon and Kyogre are forced to team up against a new, greater threat that endangers their respective habitats. Maybe a powerful alien - like Pokemon arrives on Earth and starts draining the oceans and drying up the land simultaneously. Another idea is a story where a young trainer has the ability to communicate with both Groudon and Kyogre and tries to broker peace between them, as their eternal struggle is causing chaos for the people and other Pokemon. Or perhaps a plot where Groudon and Kyogre discover they are part of an ancient prophecy and must combine their powers in a specific way to save the world from a cataclysmic event.