One common theme is revenge. Since Jane is often portrayed as a wronged character, many fanfictions focus on her seeking revenge against those who have wronged her in the past.
One common theme is redemption. Given their dark and violent pasts, many fanfictions explore the idea of either Jeff or Jane seeking redemption through their relationship. Another theme is the power of love to change, as they are two very damaged individuals and love might be the thing that can transform them.
One common theme is the struggle between good and evil. Jane is often portrayed as more of the 'good' side trying to stop Jeff who is seen as the 'evil' one. So there's a constant battle of morals.
One common theme is the battle between good and evil within their relationship. Since Jeff is a killer and Jane is often portrayed as more of an anti - hero or hero figure, their interactions can be seen as a struggle between these two forces.
Love - hate relationship is also very common. They are enemies by nature but in some fanfics, there's an underlying attraction or connection that they can't deny. This creates a lot of drama and tension in the stories.
One common theme is danger. Since Jane the Killer is a rather menacing character from horror lore, there's often a sense of the reader being in a dangerous situation, yet somehow attracted to her. Another theme is redemption. Some fanfics might explore the idea of Jane finding redemption through her relationship with the reader.
Another theme is often about the psychological aspect. How the female Jeff's mind works, what drives her to kill. It might also explore her backstory more deeply, like if she had some sort of trauma in her past that led her to become a killer. Fanfictions often go into detail about her inner thoughts and emotions, which makes it different from the original male Jeff the Killer concept.
Love is a very common theme. Their relationship, whether it's the budding of their love or the challenges they face as a couple. Another theme is adventure, as they often go on quests together. And power, like how Thor's godly powers interact with Jane's scientific knowledge.
One common theme is friendship. Their bond and how they support each other through different situations. For example, in some fanfictions, they help each other deal with family issues.
Common themes include growth. Edward and Jane usually grow as individuals and as a couple throughout the fanfiction. Family also plays a role in some stories, either their own families influencing them or them creating a new family unit together. And the theme of mystery is often there. There might be a mystery surrounding their pasts, or a mystery they have to solve together, which adds an element of intrigue to their relationship.
A third common theme is adventure. Writers often put them in exciting situations, like exploring a mysterious forest or solving a complex mystery together. This not only tests their relationship but also adds an element of excitement to the story.