One possible plotline could be Cersei's son growing up to be a more benevolent ruler than his mother. He could see the destruction she has caused and try to make amends. Maybe he forms alliances with former enemies to bring peace to the Seven Kingdoms.
A third plotline could be that Cersei's son discovers a long - lost relative. This relative could influence him to go against Cersei's wishes. For example, if he finds out he has Targaryen blood, he might be tempted to claim the Iron Throne in a different way than his mother intended, perhaps through diplomacy and uniting the houses rather than through war and tyranny.
One interesting plotline could be an alternate universe where Jaime decides to fully turn against Cersei much earlier. He might expose her secrets to save the realm from her tyranny, leading to a complex power struggle within King's Landing.
Perhaps in the fanfiction, Cersei's son discovers a hidden power within himself. He uses this power not for domination like his mother would, but to heal the broken kingdom. He might travel across the land, learning from the common people and using his new - found abilities to bring prosperity.
One possible plot could be that their son discovers the truth about his parents' tumultuous relationship. He might struggle with the knowledge that his mother had affairs and his father was not the ideal man he seemed. This could lead him on a journey of self - discovery, trying to figure out his place in the Seven Kingdoms.
One interesting Cersei fanfiction could be about her early days in King's Landing before all the chaos really began. It might explore her relationship with her father in more depth, showing how he influenced her rise to power. Another could be a 'what if' scenario where she forms an unlikely alliance with a character she normally despises, like Daenerys. They could team up against a common enemy, perhaps the Night King, and in the process, Cersei has to confront her own prejudices and power - hungry nature.
In an interesting fanfiction plot, Cersei's son could be exiled from King's Landing. During his exile, he forms a band of outcasts. Together, they build a new community away from the power struggles of the capital. As he grows, he realizes that his mother's way of ruling is wrong. Eventually, he returns to King's Landing with his new - found wisdom and tries to overthrow his mother's tyrannical rule, not to take over but to establish a more democratic and fair system for the people of Westeros.
Another possible storyline is a more character - study - based one. It could explore their relationship from a different perspective, perhaps delving deeper into their childhood and how it shaped their incestuous relationship. Maybe there are hidden memories or events that the show didn't fully explore, and fanfiction can be a great place to dig into those aspects of their characters.
One interesting aspect could be the exploration of Cersei's character in alternate scenarios. For example, in some fanfictions, her relationships might be developed in different ways. Maybe she forms an unexpected alliance with a character she previously hated, which could lead to new power dynamics and plot twists.
One possible storyline could be that Cersei's daughter rebels against her mother's tyrannical ways. She might see the destruction Cersei has caused and decides to take a different path, perhaps allying with the Starks to bring peace to Westeros.
He could influence events by being a voice of reason in Cersei's court. If he's intelligent and perceptive, he might be able to persuade his mother to make more diplomatic decisions rather than always resorting to force.
One idea could be that Cersei's bastard rises to power in secret. He or she could form alliances with unlikely characters, like some of the smallfolk who have been overlooked. They might use their wits and charm to gain support, all while hiding their true identity from the powerful families in Westeros.