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.
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.
In 'dark Sansa Stark fanfiction', Sansa can be more assertive. Unlike in the original where she is often a victim of circumstance, here she takes charge. For instance, she might not wait for others to rescue her but actively plot her own escape and revenge.
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.
Sansa would be more assertive in her political moves. She has seen the consequences of inaction and bad decisions in the future. So, she would be quicker to make decisions that benefit her family and herself. For example, she might be more involved in military strategies to protect the North.
Another interesting one is 'A Pregnant Sansa in King's Landing'. This fanfiction takes a different approach. It focuses on Sansa's pregnancy while she's still in the heart of the political chaos in King's Landing. It shows how she uses her wits and strength, even in her pregnant state, to navigate the dangerous court politics.
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.