One consequence could be a shift in the power balance. The Mountain was a powerful fighter in service of certain lords. His death would leave a power vacuum among his allies. Robb Stark, on the other hand, would gain more notoriety. His reputation as a fearsome and capable leader would spread, making his enemies more cautious of him.
There could be revenge attempts. The Mountain had his own followers and those who supported him. They might seek to avenge his death by targeting Robb Stark or his allies. This could lead to more battles and bloodshed in the fanfiction world. Also, it might change the political landscape as different factions would start to realign themselves based on this new development.
Well, in the fanfiction world, Robb Stark might also get some unexpected help. Maybe there are some magical elements involved. A wizard or a sorceress could weaken the Mountain's strength or defenses. This would give Robb an edge in the fight. Then, with his courage and fighting skills, he could step in and slay the Mountain.
The Old Gods themselves would be crucial. They could be represented in various forms like the weirwood trees. And there might be some sort of priest or seer who serves as an intermediary between Robb and the Old Gods, guiding him through the spiritual experiences.
It could lead to a major shift in the power dynamics of the story. Maybe it would prevent the Red Wedding or cause other unforeseen conflicts.
I recommend 'Robb Stark: The Lost Legacy'. This fanfiction focuses on an alternate timeline where Robb survives. It's interesting as it explores how he would have changed the course of the story. It has some great character development and interactions with other key characters from the series.
A sense of adventure is also present. They were in the middle of a war - torn Westeros. Fanfictions might take them on different adventures together, away from the main battles, or they could be involved in secret missions that test their relationship. Also, the theme of loyalty, both to each other and to their respective causes, is explored. How they balance their loyalty to each other with their loyalty to their families and kingdoms is a rich area for fanfiction writers.
There's a fanfic titled 'Robb Stark's Sister: A Tale with Theon'. In this one, the female Robb Stark character is really strong - willed. She has her own ideas about the future of Winterfell and her relationship with Theon is full of twists and turns. The author does a great job of showing how their different backgrounds shape their interactions. It's an interesting read if you like character - driven stories.
One common theme is leadership. Robb Stark is a leader, so many fanfics explore how he leads his men, makes strategies, and deals with political situations.
A prevalent theme in Robb Stark time travel fanfiction is the alteration of history. Robb, with his knowledge from the future or past, depending on the direction of his time travel, attempts to change the course of events in Westeros. This often involves political intrigue as he has to navigate the complex power dynamics all over again. Also, self - discovery is a theme. As he experiences different timelines, he learns more about himself and his capabilities. For example, in some fanfics, he realizes that his leadership skills can be applied in different ways than he originally thought.
One great 'Robb Stark OC fanfiction' is 'The North's New Hope'. It has an original character who becomes an important ally to Robb. The story is full of political intrigue and battles, just like in the original 'Game of Thrones' setting.
One possible ending is that Robb Stark becomes a great and respected king, ruling over a prosperous North. Another could be that he steps down after achieving victory and hands over the power to someone he trusts, perhaps to live a more peaceful life.