Perhaps there could be a crossover where some of the characters from Game of Thrones have supernatural abilities like the characters in Supernatural. Arya Stark could develop the ability to see ghosts like Sam does. She could use this new - found ability to gain an edge in her revenge quest. Meanwhile, Castiel from Supernatural could visit Westeros and get involved in the battle between good and evil there, siding with the Starks as he sees them as the more 'righteous' side in the fight for the Iron Throne.
One possible plot could be that the Winchesters from Supernatural end up in the world of Game of Thrones. They could be on a hunt for a demon that has somehow found its way into Westeros. Maybe this demon is influencing the actions of some of the power - hungry lords, like Littlefinger. The Winchesters would have to navigate the complex politics of the Seven Kingdoms while also trying to figure out how to exorcise the demon without getting caught up in the wars for the Iron Throne.
Perhaps Bella could be a key figure in a crossover. She could be a 'dragon rider' in a sense, using her connection with Edward (similar to the bond between a dragon and its rider in Game of Thrones). Her immunity to vampire powers could translate to some sort of immunity to the dark magic in Westeros. The werewolves from Twilight could be allies with the Stark direwolves, and together they fight against common enemies, like an army of the dead led by a Volturi - like figure.
Imagine that the Tesseract accidentally opens a portal between the Marvel universe and Westeros. The Avengers come through and are immediately caught in the middle of the War of the Five Kings. Tony Stark might befriend Tyrion Lannister, both being intelligent and a bit of an outcast in their own worlds. Thor could find common ground with the Red Priests who worship the Lord of Light, as it has some similarities to his own beliefs. The Avengers would then have to choose sides in the war while also preparing for the greater threat of the Others, which they learn about from the Night's Watch.
One interesting plot could be that AOC (assuming it's a character from another source) somehow gets transported to the world of Game of Thrones. She could use her modern - day knowledge and ideals to try and change the political landscape. For example, she might introduce concepts of equality and democracy to the feudal system of Westeros, which would surely stir up a lot of conflict among the different houses and power - hungry individuals.
A cool plot could be that the people of Westeros mistake Iron Man for some kind of powerful sorcerer because of his high - tech suit. The Lannisters might try to recruit him for their own gain. But Iron Man, being the hero he is, would see through their schemes. He could then start his own quest to find a way back home while also getting involved in the fight against the various threats in the Game of Thrones world. He might end up using the resources in Westeros to upgrade his suit in unique ways, like using Valyrian steel in its construction.
One possible plot could be Merlin, with his magic, finding himself in the world of Game of Thrones. He might use his powers to try and influence the power struggles. For example, he could help Daenerys control her dragons better or assist Jon Snow in his fight against the White Walkers. Maybe he would be seen as a sorcerer from a far - off land and have to prove himself to the different factions in Westeros.
The plot could involve a crossover of the powers. In the world of Bloodborne, there are powerful blood-based abilities. Imagine if a character like Daenerys Targaryen got access to some of these powers. She could become even more of a force to be reckoned with, using the blood powers along with her dragons. It would change the power dynamics in Westeros completely.
Another plot could involve a White Walker invasion in Skyrim. The Night King could lead his army through a magical portal that connects the two worlds. The people of Skyrim, including the various guilds, would have to team up with the houses of Westeros to fight this common enemy. The mages of Skyrim could share their knowledge of magic with the Red Priests and vice versa.
In a crossover, the angels and demons from Supernatural could be interested in the Hunger Games as a form of entertainment. Castiel could send Dean and Sam to the Games to stop an apocalypse that is predicted to start there. The boys would have to blend in as tributes, learn the ways of the Games, and figure out which of the other tributes are being influenced by the supernatural beings pulling the strings behind the scenes.
One idea could be an OC who is a healer in King's Landing during Joffrey's reign. The OC secretly tries to undermine Joffrey's cruel rule by using their medical knowledge to help those he persecutes. They might start by treating the families of those unjustly imprisoned. This could lead to a dangerous game of cat and mouse with Joffrey and his cronies as they suspect someone is working against them.
The plot could revolve around the children of Arya Stark. They inherit her skills and sense of adventure. They embark on a journey to discover a long - lost secret of the First Men that could change the balance of power in Westeros. However, they are not alone in this quest. There are other families' next generations also after this secret, leading to a race full of intrigue, battles, and unexpected alliances.