A theme that frequently appears is the power of their connection. Their combined powers or just their emotional connection can be a big part of the story. Also, there's the theme of acceptance. They accept each other's flaws and grow together. In some fanfictions, they face challenges that test their relationship, but in the end, acceptance prevails.
One common theme is friendship. Rei and Usagi have a strong friendship in the original series, and fanfictions often expand on that. They might go through challenges together and come out stronger.
Another theme is cultural exchange. Goku is from a more action - oriented, martial - arts - based culture in Dragon Ball, while Usagi is from a magical girl anime with a different set of values. Fanfictions may play with how they introduce their respective cultures to each other.
One common theme is the 'forbidden love' aspect. Since Jadeite is often an antagonist in the Sailor Moon universe and Usagi is the protagonist, their relationship goes against the natural order, which makes for an interesting and often angsty story. Another theme could be 'redemption'. Jadeite might be shown as trying to redeem himself through his relationship with Usagi.
One of the typical themes is the contrast between their personalities. Haruka is often seen as more cool and aloof while Usagi is bubbly. Fanfictions play with how these different personalities interact. Also, the theme of protecting each other is quite common, especially in stories where they face threats together.
Another theme is the culture clash. Goku comes from a martial - arts - focused, somewhat simple - living world in Dragon Ball, while Usagi is from a more magical and girly world in Sailor Moon. Fanfictions play with this difference, like when they first meet and don't understand each other's ways of doing things. It can lead to some really funny and also some really touching moments as they learn about each other.
One common theme is the exploration of their relationship's development. It often shows how they grow closer over time. Another is the struggle with their different personalities, with Misaki being more reserved and Usagi being more outgoing. And of course, there are often themes of love and loyalty.
One common theme is friendship. Their friendship often forms the basis of the story, whether it's a new friendship developing or an existing one being tested. Another theme is adventure. They usually go on some sort of journey or adventure together, facing different obstacles along the way.
One common theme is the exploration of their relationship. This could involve them falling in love, dealing with misunderstandings in their relationship, or growing closer over time. Another theme is adventure. Since they are often in some sort of action - oriented world, fanfiction might focus on their joint adventures, fighting against enemies and overcoming obstacles together.
One common theme is the development of their relationship. It could be about how they first meet and start to have feelings for each other. Another theme might be adventure. They could be on a journey together and their relationship deepens during the adventure.
Love, either platonic or romantic, is also a frequent theme. Sometimes it's a slow - burn type of love where they don't realize their feelings for a long time. Other times it's a more immediate connection that they have to navigate through various obstacles in the story.