One interesting storyline could be the male OC being a powerful knight who is initially sent to spy on Cersei but ends up falling in love with her. He has to navigate the dangerous politics of King's Landing while keeping his feelings a secret. Another could be that the male OC is a foreign noble who comes to Westeros and forms an unexpected alliance with Cersei. They face many challenges together, like dealing with the other noble houses' plots against them.
A great storyline might be where the male OC is a maester in training. He catches Cersei's eye because of his intelligence and knowledge. Cersei uses him to gain an edge in the power struggles. But as time passes, the male OC realizes he's being used and tries to find a way to either change Cersei or break free from her grasp. This could lead to a complex and tense relationship filled with twists and turns.
Perhaps in fanfiction, Violet Lemon is a healer. Cersei, after being injured in a battle or political intrigue, is forced to seek help from Violet. This encounter changes Cersei's perspective as she sees kindness and selflessness in Violet that she's not used to. They then start a journey together, with Cersei learning from Violet about different values.
One plot idea could be an OC who is a healer and tries to cure Cersei of a mysterious illness that no one else can figure out. This could lead to a complex relationship between them as Cersei is not used to depending on others.
The male OC could be a sellsword who is hired to protect Cersei. At first, she looks down on him as a common mercenary, but he proves his worth by saving her life multiple times. This causes her to reevaluate her opinion of him and a relationship begins to develop. Another plot is that the male OC is a noble from a small house who has a unique claim to the throne. Cersei tries to use him for her own political gain, but in the process, they fall in love. And there could be a plot where the male OC is a minstrel, whose songs touch Cersei's heart and make her open up in ways she never has before.
There's also 'Cersei and the Unknown Heir'. In this fanfiction, the OC is a supposed heir to a powerful house and how Cersei deals with this threat and possible alliance is the focus. It's full of political intrigue which is typical of Cersei's storylines.
To develop the male OC, start with his goals. Maybe he wants to gain power and sees Cersei as a means to that end. His appearance can also play a role. If he has a striking look, it might attract Cersei's attention. His relationships with other characters are crucial too. If he has a close friend or mentor, they could influence his actions towards Cersei. For instance, if his mentor warns him about Cersei's dangerous nature, he has to decide whether to listen or pursue his own desires.
She could also be on a quest for power. Inspired by her mother Cersei's thirst for power, she might start her own journey to gain influence. However, she may choose different methods than her mother. Instead of using manipulation and cruelty, she could focus on building alliances through kindness and mutual respect, which would be a huge contrast to the typical Lannister way.
Power is a common theme. Cersei is all about power, and when an OC is introduced, the power dynamic becomes a central focus. Whether the OC is trying to gain power through Cersei or is a threat to her power, it drives the story. Another theme is loyalty. Cersei values loyalty, but also has a hard time trusting. So, the OC's loyalty or lack thereof can create a lot of tension. Love can also be a theme, though it might be a twisted form of love, given Cersei's nature.
One interesting concept could be a crossover of magic systems. In Harry Potter, there is the use of wands and spells, while in Game of Thrones (where Cersei is from), there are different forms of sorcery. A fanfiction might explore how Cersei would react to the more structured magic of the Harry Potter world, or how Hogwarts students would view Cersei's brand of power - hungry and often cruel magic use. Another concept could be a political intrigue plot. Cersei is well - known for her political machinations in Westeros, and when combined with the politics of the wizarding world in Harry Potter, such as the Ministry of Magic and Hogwarts' internal power struggles, it could lead to some really complex and engaging storylines.
There might be a fanfiction where Cersei is a Slytherin student in Hogwarts. In this story, she could form alliances with other Slytherins and try to take over the school in a way similar to how she tries to gain power in King's Landing. Harry Potter and his friends would then have to stop her. It would be a great blend of the two universes' power dynamics and politics.
Her family dynamics are also really engaging. Fanfictions often explore her complex feelings towards Jaime. It's not just about the romantic or sexual aspect but more about the loyalty, betrayal, and the bond they share as twins. Also, her relationship with Tyrion is full of hatred and rivalry, which can be explored in great depth without any sexual undertones.