At first, their interaction would likely be very guarded. Sansa would be cautious as she has learned to be in a world full of danger. Tywin would probably see her as a young, naive girl but also a valuable asset. As time goes on, Sansa might start to challenge Tywin's ideas, which could lead to some intense exchanges between them.
Arya and Tywin could also interact in a more unexpected way. Maybe in a situation where they are forced to work together for a short time due to some external threat. During this time, Arya has to constantly remind herself of her ultimate goal of revenge while Tywin is constantly on guard against her, yet also seeing potential in her skills for his own purposes.
One common theme could be forbidden love. Given Oberyn's status in his fictional world, a relationship with another man might be considered taboo, which can add an element of drama. Another theme might be adventure, with Oberyn and his love interest going on quests or facing challenges together.
One common theme is revenge. Given Oberyn's fate in the original story, many fanfictions explore his thirst for revenge and how he might go about achieving it.
There might be some Oberyn Cersei fanfiction out there, but the 'lemon' aspect makes it a bit tricky. Fanfiction websites usually have rules against explicit content. You could try looking for more general Oberyn Cersei fanfiction that focuses on their power dynamics, their possible interactions given their characters in the show or books, rather than seeking the 'lemon' type which is likely to be hard to find in a legitimate and clean - cut way.
One great Arya and Tywin fanfiction is 'The Unlikely Encounter'. It beautifully portrays the first meeting between them and how Arya's quick thinking saves her from Tywin's wrath. Another good one is 'Alliance of Convenience' which explores the idea of them working together against a common enemy. It's full of political intrigue and character development.
In Arya and Tywin fanfiction, their dynamic can be really interesting. Tywin is a shrewd and powerful figure, while Arya is a fierce and determined young girl. One aspect could be a scenario where Arya, in her quest for vengeance, crosses paths with Tywin. Maybe she tries to infiltrate his court or army in disguise. Their interactions would be filled with tension as Tywin would likely see her as a threat, yet be intrigued by her boldness. It could lead to a complex power struggle within the story.
At first, it could be very tense. Tywin is used to being in control and having things his way, and the Stark oc would likely have her own ideas and values. So, they might start off butting heads. But as time goes on, they could start to understand each other better. The Stark oc might see that Tywin has his reasons for his actions, and Tywin could come to respect the Stark oc's strength and integrity.
I'm not sure about specific Oberyn gay fanfic works off - hand. However, you can try searching on fanfic platforms like Archive of Our Own (AO3). They have a wide range of fan - created content, and you might be able to find Oberyn - related gay fanfic by using relevant tags and filters.
There is a fanfiction called 'Oberyn's Quest'. It follows Oberyn on a journey across Westeros where he uncovers some long - forgotten secrets. The story does an excellent job of staying true to his character, his determination and his cunning nature, making it a great read for Oberyn Martell fans.