Often, there are themes of mutual support. They help each other through difficult situations. And perhaps a theme of discovery, as they learn new things about each other and themselves in the fanfic.
One common theme could be adventure. They might embark on some exciting quests together. Another could be friendship, showing how their relationship develops over time.
Since I'm not familiar with specific 'rebbeca x leechs fanfic', it's hard to say exactly. But generally in fanfics, common themes could include friendship development, adventure they might go on together, or maybe some sort of mystery they solve as a team.
I'm not sure exactly which 'rebecca x leechs fanfic' are highly recommended. You could try searching on some popular fanfic websites like Archive of Our Own. There might be a variety of stories there related to this pairing.
One common theme is friendship. Their unique bond is often explored, like how they support each other through tough times. For example, in many fics, Jill will protect Rebecca during combat situations while Rebecca will tend to Jill's wounds.
Another theme could be self - discovery. As they interact, both Yami and Rebecca might learn more about themselves. For example, Rebecca might discover new aspects of her strength or courage because of Yami, and Yami might learn more about his emotions through his relationship with Rebecca.
Some fanfics may have a theme of self - discovery. As they interact, both Billy and Rebecca might learn more about themselves, their strengths, weaknesses, and what they truly want in life, all within the context of their relationship.
Friendship is a common theme. They are often depicted as good friends who support each other through various situations.
One common theme is the discovery of self - through the relationship. Billy and Rebecca often learn more about themselves as they get to know each other better.
Overcoming hardships is also a popular theme. Since both characters have their own struggles in the original story, fanfiction might focus on how they help each other get through difficult times. For example, Asta's lack of magic initially and Rebecca's family situation could be elements that are intertwined in stories about them supporting each other through tough times.
One common theme is adventure. Since Luffy is an adventurer, the fanfictions often involve them going on quests or exploring new places together. Another theme is friendship. Their relationship usually starts as a friendship which then may develop into something more.
In many yugi x rebecca fanfictions, the theme of family also plays a role. Rebecca's family connections and Yugi's family - like bond with his friends can influence their relationship. For example, how Rebecca's family views Yugi and vice versa can add an interesting layer to the story.