One common theme could be the power dynamic. Since Bill is a powerful entity and Dipper is an adventurous character, their relationship might explore how power plays out. Another theme could be the idea of redemption for Bill through his relationship with Dipper.
There could be. However, the availability really depends on the fanfiction community. Some writers might be more interested in exploring this pairing and have created stories. You might also try checking on fanfiction forums where people discuss and share their favorite works in this area.
The 'yandere bill x dipper fanfiction' can be quite interesting. Yandere characters are characterized by their extreme jealousy and possessiveness. So, if Bill is the yandere in this scenario, he would likely go to great lengths to keep Dipper all to himself. This could lead to all sorts of conflicts, both internal and external. For example, Dipper might struggle with his own feelings towards Bill while also having to deal with Bill's overbearing and sometimes dangerous behavior.
Well, in such a fanfiction, one aspect could be the visual changes. If Dipper is genderbent, there would be a different appearance which could influence how Bill perceives and interacts with this new version. It could also lead to different story arcs. For instance, their relationship might start in a more unexpected way due to the change in Dipper's gender. It might attract readers who are interested in exploring different takes on the characters' relationships and identities within the Gravity Falls universe.
Archive of Our Own (AO3) is also a great place to search. It has a very organized tagging system. Just search for 'dipper x female bill' and you'll be presented with various fanfictions related to it. The community on AO3 is also very active, so you might find some new and interesting takes on the pairing.
One popular one might be 'The Unlikely Alliance'. It explores an interesting dynamic between Dipper and a female version of Bill. The story has a lot of mystery and adventure elements as they team up to solve some strange happenings in Gravity Falls.
First, you need to understand the characters of Bill and Dipper well. Know their personalities, motives, and how they interact in the original work. Then, for the mpreg part, you can think about how it would change Dipper's life and his relationship with Bill. You could start with an interesting concept like an unexpected event that leads to this situation.
One common theme is the power struggle. Bill is extremely powerful and Dipper is often in a position where he has to either resist or find a way to use Bill's power for his own ends. For example, in many fanfictions, Bill tries to tempt Dipper with power in exchange for something.
Another theme is the exploration of the unknown. Since Bill represents the strange and otherworldly, fanfictions often use their relationship to delve into the mysteries of the Gravity Falls universe. They might go on adventures together to discover secrets that neither of them fully understands at first.
It might develop through a series of challenges. For example, they get trapped in a magical maze. In order to get out, they have to rely on each other's strengths. Dipper's logical thinking and Female Bill's magical abilities complement each other. As they overcome each obstacle, their relationship grows from acquaintance to friendship and perhaps something more. Female Bill could start to care about Dipper's well - being in a way she didn't expect, and Dipper could see her as more than just a potential threat.