Naruto would probably find the social hierarchy in Westeros quite strange at first. But his friendly and adaptable nature would help. He might start at the bottom, but his skills would quickly earn him respect. He could become a sort of outsider hero, not fully bound by the strict rules of the hierarchy.
Well, in Naruto in Westeros fanfiction, a cool crossover might be Naruto teaching some of the Westerosi characters his ninja training methods. Imagine Arya Stark learning some of Naruto's agility and combat techniques. Also, Naruto's sense of loyalty and friendship could influence the relationships in Westeros. He might form a strong bond with Jon Snow, and together they could face the challenges of the Seven Kingdoms, like dealing with the warring factions or the threat of the Night King.
Well, one possibility is that Naruto uses his ninja skills in the world of Westeros. He might use his shadow clone jutsu to confuse his enemies in battles against the knights or rival houses. Maybe he forms an alliance with a particular house using his charisma, like he did with his friends in the Naruto world.
The White Walkers could be major antagonists. Naruto would have to use his skills to combat their undead hordes. Their magic is very different from the chakra - based abilities Naruto has, so it would be a great challenge.
A Spartan would likely find it tough to fit into Westeros' social hierarchy at first. They come from a society where merit and combat ability are highly valued. In Westeros, birthright often determines one's position. However, their combat skills might earn them respect among the military. For example, they could quickly rise through the ranks in a lord's army.
The fem Harry Potter could also change the power balance. If she aligns herself with a particular house, that house would gain an edge. Her knowledge of magic could be used to uncover secrets in Westeros, like hidden passages in castles or ancient prophecies that were previously unknown. This new information would disrupt the existing plans of the different factions vying for the Iron Throne and other power positions.
In a Westeros fanfiction with Tony Stark, he could potentially form alliances. For example, he might team up with Daenerys Targaryen. His knowledge of engineering could help her build better defenses for her cities, or even improve the design of her dragons' saddles. Also, his charisma and leadership skills could influence the political landscape of Westeros in unexpected ways.
Fanfiction.net is also a good place to search. It has been around for a long time and has a significant amount of content related to Westeros. Just use the search function and type in relevant keywords like 'Westeros watches' to find what you're looking for.
One great Westeros watches fanfiction could be those that explore the backstories of the various watch members. For example, a story about how a particular ranger joined the watch and his early adventures on the Wall.