Another idea is that Sansa, on her journey to regain power in the North, meets Doran Martell who offers her his support in exchange for her help in dealing with the political unrest in Dorne. This could lead to a series of adventures where they have to face common enemies and also deal with the cultural differences between the North and Dorne. For example, Sansa might introduce some of the North's traditions to Dorne and vice versa.
Some fandom - specific forums or communities might also be a great source. These are often places where fans discuss their favorite pairings and sometimes share their own fanfictions or recommend ones they've read. For example, there could be a Game of Thrones - focused forum where fans of this particular pairing might gather and exchange fanfiction resources.
One idea could be that Tyrion and Sansa's baby becomes a symbol of hope in a war - torn Westeros. The child might grow up with unique diplomatic skills, inherited from both parents, and strive to bring peace among the feuding houses.
Perhaps the fanfiction could focus on how Sansa and Tywin's relationship changes during the pregnancy. Tywin, who is usually cold and calculating, might show a softer side as he awaits the birth of his child. Sansa, on the other hand, could use the pregnancy to gain knowledge about the Lannisters' secrets and power plays. She could be secretly plotting her revenge while pretending to be compliant. The pregnancy could also bring about a change in the power dynamics within King's Landing, with different factions vying for control over the unborn heir.
A possible plot for 'Harry Potter and Sansa fanfiction' is that Voldemort has an interest in Westeros for some reason. Harry, with Sansa's help, tries to figure out what Voldemort wants there. Sansa, on the other hand, sees the similarities between Voldemort's tyranny and the tyrants she has faced in Westeros. They might also find that there are ancient spells in Westeros that could be used to defeat Voldemort, and Sansa plays a crucial role in uncovering them. Along the way, they learn from each other's cultures and ways of fighting.
A plot could involve Sansa being captured by the Night King. Instead of fearing him, she tries to communicate with him. She realizes that the Night King was once a man wronged by the world of the living. Together, they form an unlikely alliance against a greater threat that is emerging in Westeros, something that endangers both the living and the dead. This would turn the traditional view of their relationship on its head.
One plot idea could be that Tywin, seeing Sansa's value as a political pawn, decides to use her in a different way than originally planned. Instead of marrying her off to Tyrion, he takes her under his wing to teach her the ways of politics in Westeros. This could lead to an unlikely bond between them as Sansa tries to navigate the dangerous world of the Lannisters while still holding onto her Stark identity.
One idea could be that the OC is a healer from a far - off land who comes to Winterfell. Sansa is initially suspicious but as she sees the OC's kind heart and skills in treating the wounded, she warms up. The OC could also have some secrets about a possible threat coming to the North that they share with Sansa, and together they start to prepare for it.
One idea could be that Jon and Sansa travel back to the time before their family's downfall. They could then use their knowledge of future events to prevent Ned Stark's execution. This would completely change the course of the story and they might be able to save many of their family members.
One plot idea could be Sansa using her wits to outmaneuver Ramsay in the political arena of Winterfell. She could secretly gather allies among the servants and smallfolk who have been oppressed by Ramsay. Another could be a scenario where Ramsay tries to break Sansa's spirit but instead she finds an inner strength that he never anticipated, leading to a power struggle within the walls of the castle.
Another plot could be that Sansa's daughter discovers a long - lost secret about the Stark family. Maybe she finds a hidden passage in Winterfell that leads to a chamber filled with ancient Stark artifacts and scrolls. This discovery could put her in danger as others might want to get their hands on the secrets she uncovers, but it also gives her a chance to learn more about her family's history and power.