What could be the plot of a 'Secret Betrothal Arianne' fanfiction?

Obviously, Arianne herself is a central character. Her betrothed would be another important character. He could be a noble from another land, perhaps with a dark and mysterious past. Then there could be Arianne's family members, like her father who might be the one arranging the betrothal for political gain. Her friends or servants could also be characters, they might help her in her attempts to deal with the situation.

A plot could revolve around Arianne Martell traveling to the North. She meets Jon Snow, and at first, they are suspicious of each other. But as they get to know one another, they realize that they both have a strong sense of justice. They start to work together to improve the lives of the people in the North, and love blossoms between them as they face various challenges together, such as dealing with famine or bandit raids.

The fanfic could be centered around a prophecy. The OC Targaryen has a prophecy that is somehow related to Arianne. They meet, and while trying to figure out the meaning of the prophecy, they fall in love. However, there are forces that don't want the prophecy to be fulfilled, and so they have to fight against these enemies while also exploring their relationship.

The plot could revolve around a love story. Oc Targaryen might meet Arianne Martell during a tourney or a grand event in Westeros. Instantly attracted to each other, they would have to face many obstacles. Arianne's position in House Martell and the expectations placed on her, and Oc Targaryen's own Targaryen legacy and the eyes of the realm upon him. Their love would be a forbidden one in the eyes of some, but they would fight against all odds to be together.

Well, perhaps in the fanfic, the betrothal is part of a long - forgotten magical pact. Harry, being the hero he is, feels a sense of duty to uphold it. Daphne, on the other hand, is a complex character. She might be initially cold towards Harry but as they face various magical challenges together because of the betrothal, they gradually fall in love. For example, they might have to deal with dark wizards who want to use the betrothal for their own evil purposes.

It could be about Naruto having a secret power that he discovers late in his journey. Maybe it's a special chakra form that gives him abilities he never thought possible.

Maybe Naruto secretly admires the Uchiha's Sharingan ability and tries to learn more about it on his own. He could be collecting information about the Uchiha clan's history and techniques without anyone knowing.

One possible plot could be that Draco's demigod status is a closely guarded family secret. But as the story progresses, things start to unravel. His demigod powers could attract the attention of dark forces. He then has to decide whether to embrace his demigod side and fight against these threats or try to hide it and hope the danger passes. This internal struggle could be a major part of the plot, along with his external battles.

It could be about Harry and Luna going on a secret adventure in the Forbidden Forest. Maybe they discover a new magical creature that no one else knows about.

It could be about Naruto and Hinata going on a secret adventure together. Maybe they discover a hidden place in Konoha that no one else knows about and have to protect it from some sort of threat.