One common theme could be friendship. Given their on - screen chemistry (if they have worked together), fanfics might explore their characters' friendship in different scenarios.
You can try fanfiction websites like Archive of Our Own. There are often a lot of fanfics about various actors and characters there.
One common theme is the struggle between loyalty and love. Paul is often part of a pack with its own rules and loyalties, but he has feelings for Bella. Another theme is the idea of the outsider. Bella is usually an outsider in the werewolf world, and Paul's relationship with her can highlight this.
One common theme is friendship. Since Percy and Paul are from different worlds in a way, their journey to become friends is often explored. Another theme is discovery. Paul is often discovering the magical world that Percy is a part of.
One common theme is exploration. Since it's set in the twilight, there are often unknown areas to discover. Paul usually goes on adventures exploring these uncharted parts of the twilight world.
A common theme is the power dynamic. Paul's possessiveness often creates an unequal power balance in his relationship with Bella. Another theme is protection. Since Paul is possessive, he sees himself as Bella's protector against all sorts of threats. And love, of course, is a major theme. His possessiveness is rooted in his deep love for her.
One common theme is the struggle between different supernatural worlds. Since Paul is a werewolf and Bella is involved with vampires, there's often a theme of conflict and coexistence.
I can't say for sure as I haven't studied Jake Paul gay fanfic extensively. But common themes in fanfics in general might include friendship turning into something more, or exploring different relationship dynamics.
One common theme is the idea of family. Since it's about being adopted by Logan Paul, there's a focus on how the new family dynamic works. Another theme is adventure, as Logan Paul is known for his adventurous content, so the fanfic often has the adopted character joining in on his exciting escapades.
Love and commitment are common themes. Since Bella is Paul's wife in these fanfics, their relationship is often centered around deep love and the commitment they have to each other.
The relationship between the young and the old or the powerful and the powerless is also a theme. In stories like 'The Lumber - Room', we see how a young boy challenges the authority of the adults. It shows the different perspectives and power dynamics between different age groups.