The OC son could start off as a naive and sheltered young man, but after Jon Arryn's death, he is forced to grow up quickly. He becomes more cynical and distrustful of those around him, especially the nobles in King's Landing.
Perhaps the OC son has a special ability or gift that Jon Arryn was trying to protect him from being exploited for. After Jon Arryn's death, the son has to learn to control this ability while also dealing with the power struggles in King's Landing. He could be a key figure in the fight against the White Walkers, using his unique skills to help the living, all while trying to uphold his father's legacy.
One idea could be that this adult son might have been involved in the political intrigue in King's Landing. He could have been a rival to Littlefinger, using his father's influence and his own wits to try and maintain the stability of the realm. Maybe he would have uncovered some of Littlefinger's schemes earlier, preventing some of the chaos that ensued in the series.
One interesting fanfiction could be about Jon Arryn's son surviving in secret and emerging to claim his father's legacy. He might have been hidden away by a loyal servant and grows up in exile, learning the ways of the world far from the politics of King's Landing. When he returns, he causes a stir as he tries to uncover the truth about his father's death.
He could impact the story by influencing the Vale. Since Jon Arryn was an important figure in the Vale, his son would have had a certain amount of power and respect there. He might have been able to raise an army from the Vale earlier than what happened in the original story, and this army could have been a deciding factor in battles, like the ones during the War of the Five Kings.
Suppose Jon Arryn's son forms an alliance with the Iron Islands in fanfiction. This would be a very different scenario from the original plot. With the Iron Islands' naval power and his own claim to power in the mainland, they could create a new power bloc. This could disrupt the balance of power between the other houses and change the way wars are fought and alliances are made in Westeros.
The 'Game of Thrones' world is vast and full of possibilities in fanfiction. Regarding Jon Arryn's wife in a Blackfyre - related fanfic, it's likely that the fanfic author has crafted a unique story. It could be that the wife is a character who is a part of a secret Blackfyre plot, or she might be a noblewoman from a house that has some connection to the Blackfyre legacy. However, without actually delving into the fanfic, we can only speculate about who she might be.
In fanfiction, Jon Snow's character development might be more focused on his ability to balance his love for Ygritte and his loyalty to the Night's Watch. He could become more conflicted or find a way to reconcile the two. For Ygritte, her development could be about her growing understanding of the southern world through Jon. She might become more accepting or try to change the wildling ways to fit with Jon's world.
Yes, there might be. The Game of Thrones fandom is vast, and many creative fanfics exist. You can start by looking on popular fanfic websites like Archive of Our Own or FanFiction.net.
Well, he could be a character who has been reimagined. Jon Arryn in the original series was an important figure. In this fanfic, the 'Brightflame' addition might suggest some sort of connection to a more flamboyant or perhaps magically - inclined lineage. It's possible that he has abilities or a backstory that ties him to this 'Brightflame' concept, which could make him a key player in the fanfic's plot, different from his role in the original story.
The concept of heir in a 'Game of Thrones' fanfic involving Jon Arryn and Brightflame is highly variable. There are so many factors at play. The world of 'Game of Thrones' is full of complex family trees and political relationships. It's possible that an heir could emerge from a previously unthought - of branch of the family. Maybe there's a secret marriage in the past that ties a character to both Jon Arryn and Brightflame in a way that gives them a legitimate claim to be the heir. And then there are the power - hungry lords and ladies who might try to manipulate the situation to their advantage, putting forward their own candidates as the heir, whether they have a real claim or not.