The Stark family would be in a much stronger position. Robb Stark would not be killed, which means the North would remain united under his leadership. This could potentially change the entire power dynamic in Westeros. The Boltons and Freys would be seen as traitors and might face severe consequences from the other houses.
I haven't come across a fanfiction with that exact plot. Fanfiction often explores different relationships and storylines in the 'Game of Thrones' universe. While Arya and Jaqen have an interesting relationship, pregnancy isn't a typical aspect explored in mainstream fanfictions about them. It could be that it exists in some more niche or less well - known works, but it's not something I've seen frequently.
She could use her Faceless Men skills. Maybe she disguises herself as one of the serving staff. Since she has been trained to blend in and move unnoticed. She could then poison the wine or food that was meant for the main players in the Red Wedding. This way, she can stop the massacre before it even starts.
A female mentor or an older female friend could be important. This character could provide a different perspective. She might come from a different background or have unique experiences related to menstruation. She could offer Arya wisdom and guidance that her family members might not, like how to handle social situations when on her period or how to embrace this new part of her femininity.
If Arya is sent to the past, she might first try to find a way back to her own time. But in the meantime, she could end up influencing key historical events. Maybe she'd get involved with the Targaryen rule and change the course of their downfall. Or she could befriend some of the great warriors of the past and learn new fighting techniques that she could bring back with her if she ever returns to her own time.
Well, it could be about Arya's confusion and discovery when she first gets her period. Maybe it shows how she copes with the physical and emotional changes, like feeling a bit scared or embarrassed at first. And how the people around her, like her mother or sister, help her understand what's going on.
In a fanfic where Arya gets captured, she might be used as a bargaining chip. Her captors could try to exchange her for something valuable, like a strategic location or a large sum of gold. Maybe they want to use her to manipulate the Starks.
One common way for Marinette to get revenge in fanfiction could be through her fashion skills. She could design something that makes Lila look foolish. Like creating a dress for an event that has a hidden message or design that mocks Lila's lies when she wears it. It's a more creative and less confrontational way of getting revenge, but still very effective in showing Lila that Marinette is not one to be trifled with.
One story could be that the husband found out his wife was cheating. Instead of getting violent, he quietly gathered evidence. Then he exposed her affair to their families and friends, which led to her being ostracized in their social circle.
One common theme is betrayal. In these novels, usually one of the characters in the relationship feels betrayed, which then triggers the need for revenge. For example, in a case where a partner has an affair before the wedding, the other partner might seek revenge during the marriage. Another theme is power struggle. In a marriage, there is often a fight for power, and when one side feels overpowered or mistreated, they may use revenge as a means to regain control. For instance, a character who has been financially exploited in a marriage might plan a revengeful act to turn the tables.