One idea could be exploring a new character who discovers a hidden power within the rings that was previously unknown. This could lead to a whole new adventure and conflict within the fanfiction world.
You could write a fanfiction focusing on the relationship between different races in 'The Rings of Power'. For instance, how elves and humans interacted beyond what was shown in the series. What if there were secret alliances or romances between them? Also, a fanfiction about the magic in the world of 'The Rings of Power' could be really cool. You could expand on how the magic works, create new spells, or explore the limitations of the existing magic system.
Give the character real - life - like flaws. A character who is too perfect isn't believable. So, if your character is a powerful ring - bearer, they could have a fear of heights which is a hindrance in some situations. Also, let their actions be consistent with their personality. If they are a kind - hearted person, they won't suddenly start acting cruel without a good reason, especially when it comes to using the power of the rings.
A possible plot could be that a hobbit, who has a very charming personality, accidentally gathers a harem of female characters from different races. They join him on his journey, which is not just about destroying the One Ring but also about promoting unity among the different races in Middle - earth. This harem then becomes a symbol of hope and cooperation, showing that different races can coexist and work together.
Perhaps the gamer could start a new fellowship, not to destroy the One Ring but to study and preserve the magic within all the rings. They could travel across Middle - earth, gathering knowledge and artifacts related to the rings, facing challenges from both Sauron's forces who think they are trying to undermine their plans, and from those who fear the power of the rings being misused.
A plot could revolve around a team-up that no one expected. Like a villain and a hero from different universes having to work together in the Tournament of Power. They start off distrusting each other but gradually learn to respect and rely on one another. This could add a whole new layer of drama and character development to the fanfiction.
One idea could be exploring the origin of the 'power of darkness'. Maybe it was a forgotten magic that gets rediscovered by a young protagonist.
One idea could be that the OC is a healer who joins Aragorn's journey. They meet during a battle where Aragorn is injured and the OC uses their unique healing skills to save him. This starts a bond between them as they travel together, with the OC providing medical aid to the whole fellowship.
One idea could be that the Dragonborn from Skyrim somehow ends up in Middle - earth. Maybe they are mistaken for a powerful wizard due to their Thu'um abilities. Another plot could involve the One Ring being found in Skyrim and the different factions vying for its power, just like in Middle - earth. A third interesting plot would be characters from Lord of the Rings traveling to Skyrim and having to deal with the cold, the dragons, and the political unrest there.
One idea could be to explore what would happen if Frodo was accompanied by a magical creature that could sense the Ring's power and help him resist its allure better. This creature could be a new creation specific to the fanfiction.
One idea could be that the characters from Middle - earth accidentally stumble into Narnia through a magical portal. For example, Aragorn and Legolas could find themselves in the middle of the Narnian forest and team up with the Narnians to fight a common enemy, like an ancient evil that threatens both worlds.