If the male OC Lannister was a proud and ambitious type, he would likely interact with Cersei with a mix of respect and rivalry. He'd try to gain her favor while also making sure she didn't see him as a threat. With Tyrion, he might initially look down on him but later come to respect his intelligence. And when it comes to Jon Snow, he could start off as dismissive but as he realizes Jon's leadership skills, he might try to form an alliance.
A more benevolent male OC Lannister would interact very differently. With Daenerys, he might be intrigued by her quest for the Iron Throne and try to broker a peace deal between her and the Lannisters. When it comes to Ned Stark, he could have a begrudging respect for Ned's sense of honor. And with Arya, he might be a bit fearful as he hears of her skills as an assassin, but also try to find a way to use her skills for his own ends, perhaps by offering her a pardon in exchange for her services.
Imagine a male OC Lannister who is a bit of a maverick. With Jaime, he would constantly challenge Jaime's loyalty to the family, asking him if his love for Cersei is clouding his judgment. When interacting with Sansa, he would see her as a valuable pawn in the game of thrones. He might try to marry her off to a Lannister ally to strengthen their position. And with Theon Greyjoy, he would view him as a weakling at first but later realize Theon's potential for redemption and try to use that to his advantage in the political turmoil of Westeros.
Consider their upbringing. If they were raised away from the main Lannister stronghold, they might have a different set of values. Maybe they were raised by a kind - hearted servant who taught them to be more empathetic. So their personality could be a mix of Lannister pride and this new - found empathy. They could be conflicted between loyalty to their family and doing what is right according to their own conscience.
One possible plot could be a young Lannister male OC who, unlike his power - hungry relatives, is more interested in the arts and knowledge. He could secretly befriend a maester and learn about ancient Valyrian lore. This would put him at odds with his family as they see his pursuits as a waste of time. He might then use his knowledge to try and broker peace during the war, facing many challenges along the way.
Perhaps an OC Lannister who is a talented healer. In a world full of wars and battles in Game of Thrones, a healer Lannister could be an interesting addition. They might have to deal with the moral dilemma of healing both their own family's enemies and allies. They could also have a secret love affair with a member of another house, which would add a layer of drama.
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.
One of the main themes is family dynamics. The Lannisters have a complex family structure, and the OC has to find his place within it. Also, the theme of survival is prevalent. In the cut - throat world of Game of Thrones, the OC has to fight to stay alive and relevant. And then there's the theme of reputation, as the Lannister name comes with both advantages and burdens.
One great 'OC Son of Lannister' fanfic is 'The Lannister's Heir'. It explores the journey of the OC as he tries to navigate the complex politics of Westeros. Another is 'A Lannister's Redemption' which shows how the character battles with the family's reputation.
In OC fanfiction involving Tywin Lannister and the Starks, Tywin's strategic mind is a central aspect of his portrayal. He is always looking for ways to strengthen his house's position. The Starks, on the other hand, are known for their integrity. An OC could be a healer, for instance, who treats the wounded from both sides during a battle. This OC's presence might lead to some unexpected interactions between Tywin and the Starks, like Tywin seeing the Starks in a more sympathetic light due to the OC's influence.
To develop their relationship realistically, start with their initial meeting. If the male OC is from a different background, there should be some level of distrust or misunderstanding at first. For example, if he's from a poorer region and she's a Lannister, she may look down on him. As they interact more, small acts of kindness or shared interests can start to break down the barriers. For instance, if they both have a love for a certain type of horse, it can be a starting point. Their relationship should also be affected by the political climate around them. If Cersei's power is threatened, she may be more hesitant to show affection for the male OC for fear of looking weak.
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.
Harry would likely be cautious around Tywin. He's used to dealing with villains, and Tywin's cold and power - hungry demeanor would set off alarm bells. Tywin, in turn, would probably see Harry as an enigma, a boy with strange powers that could be useful or dangerous. He might try to manipulate Harry into doing his bidding.