Transformation is a big theme. The process of turning into a werewolf and back is often described in detail, sometimes with a unique twist that fits the Adventure Time aesthetic. There's also the theme of the werewolf being an outcast. Since Adventure Time has a lot of misfits, the werewolf character might be seen as different even among the already diverse population of Ooo. They might have to find their place in this strange land, which can lead to some really heartwarming or action - packed stories.
Some fanfictions might explore the origin of werewolves in the Adventure Time universe. How did they come to be? Are they a result of some sort of magic gone wrong? Or perhaps they are an ancient race that has been in the Land of Ooo for a long time? Writers often like to create backstories for these werewolf characters, which can add depth to the fanfiction.
One common theme is his struggle to fit in. Lemongrab has such a distinct personality compared to the other characters in Adventure Time, so a lot of fanfics focus on how he tries to be part of the community.
One common theme could be self - discovery. Bronwyn might be on a journey to find out who she really is in the wacky world of Adventure Time. Another theme could be friendship. Just like in the main show, Bronwyn could form strong bonds with other characters.
One common theme is friendship. Finn is all about his friends in the show, and in fanfics, his relationships with Jake, Princess Bubblegum, and others are often explored further. Another theme is self - discovery. Finn is constantly growing and learning about himself, and fanfics often take this aspect and expand on it. For example, in some fanfics, he discovers new powers or abilities that make him question who he really is.
Romance is a very common theme. Werewolves often fall in love with humans or other supernatural beings. Another theme is loyalty, as werewolves are usually very loyal to their pack. Also, the struggle between their animal instincts and their human side is often explored.
One common theme is leadership. The alpha werewolf often has to lead his pack through various difficulties like battles or dealing with other supernatural beings. Another theme is loyalty, both within the pack and towards the alpha's mate. For example, in many fanfics, pack members will risk their lives for the alpha.
Friendship is also a big theme. Harry's friends play an important role in many of these fanfics. They might help him hide his werewolf identity, or they could be the ones to encourage him to embrace it. Their friendship is tested and strengthened through the werewolf - related events in the story.
One common theme is the idea of fated mates. It's often that werewolves in these fanfics have a destined partner, and they can sense this connection on a deep, almost instinctual level.
The theme of secrecy is quite prevalent. Just like in the original Harry Potter series where he had to keep his wizarding world a secret from muggles, in werewolf Harry fanfic, he often has to hide his werewolf nature. Also, the theme of power and control is common. Harry has to learn to control his werewolf powers which can be both a strength and a danger.
One common theme is the struggle between human and beast. Since Ben 10 already deals with the idea of transforming into different alien forms, adding the werewolf element often explores the internal conflict of Ben or other characters when they are in a more animalistic state.