Jon Snow could potentially have allies like the Mormonts. They have always been loyal to the Starks. Maybe even some of the Dornish houses might side with him. They have their own reasons to oppose the current power structure in Westeros. And of course, his friends from the Night's Watch who left with him or believe in his cause could be his allies in this conquest. He might also gain the support of some of the maesters who see the value in his leadership for the future of Westeros.
The wildlings might be his allies. After all, Jon Snow has had interactions with them before. They are fierce fighters and could fight alongside him against a common enemy.
In this fanfiction, one of the key battles Jon Snow might participate in could be the Battle of the Whispering Wood. His skills as a fighter would be put to good use there, sneaking around and taking out enemies. Another could be a fictional battle near the Wall, where he defends against some new threat that has emerged during Robb's war.
He might go back to Winterfell and claim his rightful place as a Stark. This would change the whole power dynamic in the North and also his relationship with his siblings.
In this fanfiction, Jon Snow's character could develop in several ways. Firstly, his relationships with other characters might change. He may form stronger bonds with his fellow soldiers, learning to trust them more. Secondly, his understanding of politics and power could grow. As he is involved in Robb's war, he witnesses the political maneuverings that go on behind the scenes. This could make him more cynical or more determined to fight for justice, depending on how he interprets these events. Moreover, his combat skills are likely to improve, and this newfound strength could give him a different perspective on his own capabilities and his place in the world.
It's possible that he has a different vision for his life. He might have seen a different future for himself, one where he doesn't have to be bound by the rules and isolation of the Night's Watch. He may want to be more involved in the politics and power struggles of the Seven Kingdoms, rather than being on the Wall.
It's interesting because it can explore different aspects of their characters. For example, how their relationship might change if they were in different situations, like facing a common enemy or having to make difficult decisions together. It gives a new perspective on their individual personalities as well.
He did die in the novel. George R. R. Martin described his death quite vividly. Jon Snow was betrayed by his fellow Night's Watch members. They stabbed him while he was unaware. This event was a major shock in the story. But as with many things in Martin's complex world, it's hard to say for sure if death is the end for Jon. There could be some as - yet - unrevealed plot device that might bring him back. But as of what has been written so far, he is dead.
One idea could be a crossover where Jon Snow is transported to the Naruto universe. He could join Naruto's team and use his combat skills from Westeros, like sword fighting and archery, in the ninja battles. His leadership skills might also be recognized in the Hidden Leaf Village.