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.
There could be a fanfiction that focuses on an alternate universe where Tywin survives longer. In this story, he would have to deal with the changing political landscape after the events at King's Landing. He might try to regain control of the situation, perhaps by making alliances with unexpected parties. His character would be forced to adapt to new threats and challenges, which could lead to some very interesting plot developments.
One great 'Game of Thrones Tywin Lannister Fanfiction' is 'The Lion's Legacy'. It delves deep into Tywin's past, showing his rise to power in a very detailed and engaging way. The author does an excellent job of portraying his complex personality.
Archive of Our Own (AO3) is a great place to find 'Game of Thrones' Tywin fanfictions. It has a large and diverse collection, with different takes on the character, from exploring his political maneuvers to his personal relationships.
The popularity of 'Game of Thrones Tywin Lannister Fanfiction' comes from Tywin's complex character. He is a powerful, shrewd man, and fans like to explore different aspects of him. Fanfiction allows for a deeper look into his motives and backstory.
One interesting scenario could be Arya disguising herself as a servant in Tywin's camp. She could overhear his strategic plans and use that information to her advantage later. Maybe she even manages to steal something important from him without him realizing it was her.
One interesting Tywin fanfiction could be one that delves into his early years and how he rose to power. It might explore his relationships with his father and the events that shaped his cold and calculating nature.
One unique aspect could be exploring his softer side. Since he's often portrayed as a cold and ruthless man, a fanfiction could show his moments of vulnerability. Maybe he has a secret love or a friendship that no one else knows about.
Cersei would likely be furious. She sees Sansa as a rival and the idea of her father marrying the girl she hates would be intolerable. She might try to undermine Sansa at every turn. Jaime, on the other hand, might be more indifferent. He has his own issues to deal with and may just see it as another one of his father's political maneuvers. Tyrion would probably be amused and a bit worried. Amused because it's such an unexpected pairing, and worried because he knows how dangerous his father can be and how vulnerable Sansa is in this situation.
The relationship could develop into a strange sort of mutual respect. Maybe Arya saves Tywin's life in a situation, and Tywin, in return, offers her protection. They start to understand each other's motives more deeply. Arya realizes that Tywin is not just a heartless monster but a man with his own goals and Tywin sees Arya as a force to be reckoned with rather than just a Stark girl to be eliminated.