Another plot could involve reincarnating as a Stark. You could try to prevent the tragedies that befall the family. For example, by using your knowledge of future events, you might be able to stop Ned Stark from going to King's Landing, or find a way to better protect Robb during his campaigns. Since you have an insider's view of the family, you can also strengthen their relationships and alliances.
One idea could be reincarnating as a minor character, like a servant in King's Landing. You could use your modern knowledge to avoid the chaos of the city and slowly rise in power by befriending key players. Maybe you know of some herbal remedies that could save a noble from a deadly illness and gain their favor.
A third plot could be reincarnating as a Targaryen in exile. You would have to find a way to reclaim your family's throne. You could start by gathering allies among the Free Cities. Use your modern understanding of leadership and strategy to build a powerful army and navy. Maybe even form an alliance with Dany, but with your own motives, to take back Westeros and rule it in a more just way.
One idea could be a character reincarnated as a different species, like a dragon. They could then use their new form to influence the power struggles in Westeros. Another could be a reincarnated character remembering key events from the original series and trying to prevent certain tragedies from occurring. For example, if Ned Stark was reincarnated, he might be more cautious and avoid getting caught in the political traps that led to his downfall.
One idea could be exploring what would happen if a minor character like Gendry had been secretly trained in magic. He could use his newfound powers to unite the smallfolk against the warring nobles. Another plot could revolve around a female knight from the North who disguises herself as a man to fight in the wars, and along the way, she discovers secrets about the White Walkers that no one else knows. Or perhaps a fanfiction where Daenerys and Sansa form an alliance much earlier and together they reshape the power dynamics of Westeros.
A really cool 'Game of Thrones fanfiction' plot could involve the resurrection of some of the dead characters in a different way. For example, what if Ned Stark was brought back not as a vengeful wraith but as a wise advisor to a new king or queen? His honor and wisdom could shape the future of Westeros in a completely new direction. And it would be interesting to see how the other characters react to his return.
Perhaps a fanfiction where Daenerys Targaryen lands in Westeros earlier and forms an alliance with the Starks before the events of the main series. This would completely shift the political landscape and the fight for the Iron Throne. She could bring her dragons to help fight the White Walkers from the start.
One idea could be exploring what would happen if a minor character, like Gendry, had a more central role in the fight against the White Walkers. He could lead a group of common folk and prove that the power doesn't always lie with the nobles.
One idea could be that the reincarnated Lannister has all the memories of their past life. They could use this knowledge to avoid the mistakes their previous self made. For example, not getting involved in certain political schemes that led to their downfall. Another plot could be that they try to change the fate of their family members. Maybe prevent Jaime from losing his hand or stop Cersei from going down her tyrannical path.
One interesting plot idea could be the return of a long - thought - dead character with a new mission. For example, if Ned Stark somehow came back and had to navigate the even more complex political landscape of Westeros. Another could be the exploration of the relationship between Daenerys and Jon Snow in a more in - depth way, perhaps with some new challenges that test their alliance.
Another plot could involve a goddess who was once worshipped in ancient Westeros but forgotten over time. She resurfaces during the chaos of the Game of Thrones. This goddess has the power to manipulate the elements and she decides to test the worthiness of the claimants to the Iron Throne by sending various trials their way.
Perhaps a plot where the gamer character discovers a hidden aspect of the magic in the Game of Thrones world through their unique 'gamer' perspective. This could lead to new powers being unlocked and changing the power dynamics among the different houses.
Perhaps a Futa warrior from beyond the Wall who comes to the Seven Kingdoms. This character could bring new fighting techniques and a different perspective on the war for the North, and interact with well - known characters like Jon Snow in unexpected ways. They might even have knowledge of the White Walkers that could change the course of the story.