Another theme could be a romantic relationship. Some fanfictions might develop a love story between them, which often includes elements of forbidden love as their families and loyalties are complex in the original 'Game of Thrones' context. It can be interesting to see how the writers navigate this.
A third theme could be adventure. They might go on quests together or face challenges side by side. This could involve battles, political intrigue, or just exploring the vast world of Westeros. Writers might use this to show how their characters grow and change in the face of difficulties.
There's a fanfic titled 'Robb Stark's Sister: A Tale with Theon'. In this one, the female Robb Stark character is really strong - willed. She has her own ideas about the future of Winterfell and her relationship with Theon is full of twists and turns. The author does a great job of showing how their different backgrounds shape their interactions. It's an interesting read if you like character - driven stories.
You can start by looking on Archive of Our Own (AO3). It has a vast collection of Game of Thrones fanfictions, and there are likely to be many that feature a female Robb Stark and Theon. Just use the search function and type in relevant keywords like 'female Robb Stark' and 'Theon'.
Perhaps a female Robb Stark and Theon are forced into an arranged marriage as part of a political alliance between the remaining Starks and some of Theon's supporters. At first, they resent each other due to their past differences. But as they start to understand each other's motives and the greater good they are working towards, they fall in love. They then have to deal with the internal politics of their newfound union and fend off enemies who want to break them apart.
One common theme is the clash of different cultures. Harry Potter's world is full of magic and wizardry, while Robb Stark's is a medieval, feudal society. So, stories often explore how the two worlds collide and interact. For example, how magic is perceived in a world that has no prior knowledge of it.
A sense of adventure is also present. They were in the middle of a war - torn Westeros. Fanfictions might take them on different adventures together, away from the main battles, or they could be involved in secret missions that test their relationship. Also, the theme of loyalty, both to each other and to their respective causes, is explored. How they balance their loyalty to each other with their loyalty to their families and kingdoms is a rich area for fanfiction writers.
Another place could be FanFiction.net. However, the quality can vary a great deal. You might need to sift through quite a few stories to find the really good ones about female Robb Stark and Theon. But it has been around for a long time and has a huge collection.
One common theme is leadership. Robb Stark is a leader, so many fanfics explore how he leads his men, makes strategies, and deals with political situations.
If we consider a female Robb Stark in fanfiction, their relationship could develop more romantically compared to the canon. Since a female Robb might bring different emotional and social dynamics. Theon, who is often in search of acceptance, could be drawn to her in a more intense way. Their relationship could be less about power struggles and more about mutual support and affection, which would be a big departure from how their relationship was portrayed in the original story.
A prevalent theme in Robb Stark time travel fanfiction is the alteration of history. Robb, with his knowledge from the future or past, depending on the direction of his time travel, attempts to change the course of events in Westeros. This often involves political intrigue as he has to navigate the complex power dynamics all over again. Also, self - discovery is a theme. As he experiences different timelines, he learns more about himself and his capabilities. For example, in some fanfics, he realizes that his leadership skills can be applied in different ways than he originally thought.
One common theme is political intrigue. Since they are from important families, many fanfictions involve them using their relationship to gain political advantages for their respective houses. Another theme is love against all odds, as their families may not approve or there could be other obstacles in their way.