One common theme is the idea of redemption. Often, Hook is given a chance to redeem himself in some way in relation to Peter Pan. For example, he might be trying to make up for past wrongs.
One common theme is the exploration of good and evil. Often, Hook is seen as the villain, but in fanfiction, his character can be more nuanced, blurring the lines between good and evil. Another theme is growing up. Wendy represents the idea of growing up, and her relationship with the eternal child, Peter, and the more worldly Hook can be used to explore this concept.
Well, the theme of lost childhood is often seen. Hook, in some fanfictions, is seen as someone who has lost his childhood innocence and is envious of Peter's eternal youth. Another common theme is the power struggle. There's always a struggle for power between Peter, who has the power of flight and leadership in Neverland, and Hook, who has his pirate crew and his own brand of power. Also, the theme of discovery, like discovering new parts of Neverland or new aspects of each other's characters.
Another common theme is the exploration of Hook's past. Writers often create stories that dig into what made Hook become the pirate he is. This could involve his early life, his first encounters with the magical world of Neverland, and how he lost his hand to the crocodile. It gives more context to his character and his motives in the story.
One common theme is the exploration of forbidden love. Since they are supposed to be enemies, the idea of them having romantic feelings for each other is a big draw. It adds an element of taboo and excitement.
The theme of redemption is also quite popular. Some fanfics will have Hook seeking redemption for his actions, or Peter Pan realizing that his actions towards Hook might not have been entirely fair. It makes for a really interesting character study.
Another theme is the power of friendship. Despite their differences and history of enmity, many fanfictions explore how they could become friends or at least allies. They might find common ground in their shared experiences in Neverland or their mutual love for adventure.
One interesting plot twist could be that Hook is actually a long - lost relative of Peter Pan. Maybe they are related through some ancient magic or a family secret that was lost over time. This would completely change their dynamic, from sworn enemies to having a complex family - related relationship.
A common theme is the exploration of different worlds. Since Peter is from Neverland and Ariel from the underwater world, fanfictions often focus on how they interact with each other's habitats.
The theme of adaptation is very common. Peter Pan has to adapt to living with a partner, sharing his space, and making decisions together. Also, the theme of love against all odds can be seen. Given Peter's wild and free nature, it seems unlikely for him to settle down, so when he does get married in fanfiction, it's often about a love that is so strong it overcomes his natural instincts. In addition, some fanfictions explore how his marriage affects the other characters in Neverland, like the Lost Boys, Tinker Bell, etc.
Another theme is self - discovery. Henry, who may come from a more ordinary world, gets to learn about himself in the extraordinary world of Peter Pan. He discovers new abilities and strengths, and often has to confront his fears. For example, in many fanfictions, Henry realizes he can be braver than he thought when facing the challenges in Neverland.