The main characters are, as the title suggests, Waluigi and Daisy. Waluigi is often portrayed as the more mischievous or underappreciated character in the Mario universe, while Daisy is the princess of Sarasaland. In the fanfic, their interactions and relationship are the focus.
Well, in 'waluigi x daisy fanfic', a common theme is cooperation. They may team up to face a common enemy in the Mario - related universe. Also, the theme of growth is there. As the story progresses, both characters could grow in terms of their personalities and abilities. And of course, there could be a theme of mystery, like they might be involved in solving some mysterious events in their world.
You can develop Wario by showing his softer side. Maybe he has a hidden love for cute things like small Toads. For Waluigi, explore his insecurities. He's often seen as the sidekick, so show how he wants to prove himself. They can develop together by having them share their dreams and fears with each other during a long journey.
I'm not entirely sure about the existing 'god x waluigi fanfic' but generally, fanfics in this vein could be quite unique. It could be a story where God is a character in the Waluigi - centric universe. Waluigi might be constantly trying to impress God or seek his approval. This could lead to situations where Waluigi tries to outdo his rivals in a more spiritual or god - influenced context, like in a competition of good deeds or something similar.
The contrast between the two characters makes it appealing. Waluigi is a bit of a goofy, scheming character, while Rosalina is elegant and mysterious. When combined in a fanfic, it creates an interesting dynamic.
You could try looking on some major fanfic websites. Websites like Archive of Our Own or FanFiction.net might have such fanfics. Just use their search bars and type in 'god x waluigi' and see what comes up.
Maybe a fanfic where they accidentally swap bodies. This would lead to a lot of comical situations as they try to navigate each other's lives and also understand each other better in the process. For example, Luigi has to deal with Waluigi's more mischievous side while in his body, and vice versa.
A 'waluigi x rosalina fanfiction' could be about exploring an unexpected relationship between the two characters. It might involve how their different personalities interact. For example, Waluigi is often portrayed as a bit of a mischievous character, while Rosalina has a more serene and maternal quality. In the fanfiction, the writer could create scenarios where Waluigi tries to impress Rosalina in his own clumsy way, or Rosalina helps Waluigi to become a better version of himself. It could also be set in different locations within the Mario universe, like on Rosalina's Comet Observatory or in one of the many kingdoms that Waluigi has visited during his adventures.
A possible plot for a 'Waluigi x Wario' fanfic could be that they both get transported to an alternate dimension. In this strange new world, they have to rely on each other to find their way back home. Along the way, they encounter various challenges that force them to combine their unique skills. For example, Wario's brute strength and Waluigi's lanky agility could be used to overcome obstacles like giant monsters or tricky mazes. This adventure could also lead to a deeper understanding of their relationship, perhaps even a friendship that was previously unacknowledged.
Another option is FanFiction.net. It has been around for a long time and has a lot of different fanfics, including ones about Luigi and Waluigi. However, the quality can vary, so you might need to do some sifting through. You can also check out some Mario - themed fan communities on social media platforms. Sometimes, members share their favorite fanfics there.