One idea could be that Darth Vader would use his Force powers to manipulate the political situation in Westeros. He might side with a powerful house, like House Lannister, and use his lightsaber to intimidate their enemies. His presence would completely change the power dynamics as his combat skills and the Force would be a huge advantage in battles and intrigues.
Darth Vader would disrupt the power balance. He wouldn't care about the politics of Westeros in the traditional sense. Instead, he would seek to rule through fear. He might target the most powerful houses first, like the Lannisters or the Starks, to show his dominance. His Sith ideology would clash with the religions and beliefs of Westeros, causing unrest among the people.
He would be a terrifying force. Just imagine him facing off against the White Walkers. His lightsaber could cut through them with ease, and the Force might even have some effect on them. The characters in Game of Thrones would be both in awe and afraid of him. He could potentially change the outcome of the war against the undead.
If Darth Vader were in the Game of Thrones universe in a fanfic, he'd likely be a major disruptor. He could easily overpower most of the characters physically. However, the political intrigue might initially baffle him. But his strategic mind from the Star Wars universe could soon adapt. For example, he could form alliances with certain houses, perhaps using his power to intimidate them into cooperation, all while trying to achieve his own goals, whatever they might be in this new and strange world.
He would be perceived as a very powerful and fearsome being. His black armor and the red glow of his lightsaber would make him stand out. People in Westeros have never seen anything like him before, so they would likely be both in awe and terrified.
One way this could happen is through some sort of interdimensional rift. Maybe a powerful jutsu in the Naruto universe accidentally tears open a portal to the Star Wars galaxy. Naruto, being the curious and brave ninja he is, gets sucked into it. Once in the Star Wars universe, he's exposed to the dark side of the Force, which gradually corrupts him and he starts to take on the persona of Darth Vader. He might even learn some of the Sith ways from Vader's own teachings if he somehow travels back in time to Vader's era.
In the 'Harry trained by Darth Vader' fanfic, it could be that Harry becomes a much more intimidating figure. Darth Vader's training would likely focus on physical and mental discipline. So Harry could have enhanced physical abilities, like being able to move faster and react more quickly. His magic might also take on a more menacing edge, perhaps being more focused on domination rather than the more benevolent magic he was taught at Hogwarts. This would surely change the dynamic of his relationships with his friends and foes alike.
In such a fanfic, the Avengers' diverse powers would clash with Darth Vader's formidable Force abilities. Iron Man could use his high - tech suits to try and outmaneuver Vader's lightsaber attacks. Captain America might lead the charge with his shield against Vader's dark side - enhanced combat skills. It would be an epic battle of good from different universes against Vader's Sith - influenced evil.
Well, Naruto's ninja skills would be a game - changer in Westeros. He could use his Shadow Clone Jutsu to gather information in different places at once. For example, he could send clones to King's Landing, Winterfell, and other key locations. His Rasengan could be a powerful weapon against the White Walkers. And his strong sense of justice would likely lead him to side with the Starks, who also value honor and loyalty.
One idea could be a fanfic where Darth Vader has a secret apprentice who is an original character. This OC could be a young Force - sensitive being from a hidden planet. The story could revolve around Vader training this apprentice in the ways of the Dark Side, while also facing internal conflict as he sees some of his own past self in this young OC.
They could intersect in a dream - like scenario. A character in Game of Thrones, perhaps a Targaryen with their prophetic dreams, dreams of Darth Vader. This could be a sign of an impending doom or a new power rising. In the Star Wars universe, Vader has dreams and visions as well. Maybe their dreamscapes merge, and they communicate in this ethereal realm, sharing knowledge and perhaps even influencing each other's destinies in their respective universes.