Perhaps it was an impulsive decision made out of true love. In the heat of the moment, fem Harry Potter and her partner decided to get secretly married because they couldn't bear to be apart and wanted to show their commitment to each other immediately, regardless of what the wizarding society might think.
To protect the person she loves. If she's in a dangerous situation, like there are still dark forces around, a secret marriage could be a way to keep her loved one safe from being targeted by the enemies.
She might meet a powerful and mysterious wizard who has been hiding in Vegas for a long time. This wizard could be either a potential ally or an enemy. There could also be a group of young witches and wizards who are having their own adventures in Vegas and they all team up with fem Harry Potter for a wild ride full of magic, mystery, and fun.
One possible plot could be that the fem Harry Potter discovers she has a hidden connection to Mordred. Maybe she starts having strange dreams about the Arthurian era and slowly uncovers that she has some of Mordred's essence or powers within her. This could lead to her having to deal with new magical threats that are related to the Arthurian legends, while also still facing the usual challenges in the Harry Potter world like dealing with Voldemort or his followers.
One reason could be that the author lost interest. Maybe they started with a great idea of a female Harry Potter but then got distracted by other things in life or new fanfiction ideas. Another reason might be that they received negative feedback which demotivated them from continuing.
One possible plot could be that Fem Harry Potter discovers her true parentage as she grows up in the wizarding world. This revelation could cause chaos as she tries to understand her place between the two very different worlds. She might have to learn about her Norse powers in addition to her magic, and face challenges from both sides.
Maybe they are just curious about how other fans interpret their own family's story. After all, in the original story, they are an important part of Harry Potter's world.
One reason could be for protection. If there's a new dark force emerging, Harry might hide his child to keep it safe from being targeted.
It could be that she doesn't trust the people around her completely. Maybe she has a past experience where someone used her intelligence against her. So, she decides to keep it a secret until she's sure she can trust those around her with this part of herself. In the fanfiction, perhaps she's had a run - in with a false friend who tried to steal her ideas related to magic, so she's more cautious now.
One interesting plot could be how the fem Harry Potter navigates the new marriage law. Maybe she has to choose a partner from a list of candidates and she struggles between her long - held feelings for Ron and the new prospects the law presents. It could lead to a lot of romantic tension and character development.
In some fem Harry Potter marriage contract fanfictions, the plot could revolve around the discovery of a marriage contract with a foreign wizarding family. Fem Harry, being the headstrong character she is, decides to study the family's magic and culture before agreeing to the marriage. This exploration could lead to new friendships and magical discoveries. For example, she might learn a unique form of defensive magic from her potential in - laws. And along the way, she has to balance her Hogwarts life, her friends, and the looming marriage contract.
Fans of both Harry Potter and the concept of the Dragon Mother would likely be interested. People who like to see crossovers between different fictional universes might also be into it.