Another theme could be adventure. They might go on some sort of journey together, either in the Mushroom Kingdom or in some new, made - up world. It's also possible that some fanfics have a theme of redemption, where Bowser has a change of heart through his interactions with Luigi.
There are often themes of power dynamics as well. Luigi is usually seen as the underdog compared to the powerful Bowser. Fanfics may play with this dynamic, exploring how Luigi might overcome his fear or how Bowser might come to respect Luigi's quiet strength. Some fanfics may also include a touch of romance, although this is more of a niche theme compared to the others.
Some common themes include transformation. This could be in terms of Bowser's character evolving due to his relationship with female Luigi. Also, the theme of overcoming differences is quite common. In the Mario universe, Luigi and Bowser are on opposite sides usually. But in these fanfictions, female Luigi and Bowser have to find ways to get along. Additionally, themes of mystery and discovery can be present, like when they explore new parts of the Mushroom Kingdom together and uncover secrets that change their relationship.
One common theme is the idea of redemption. Sometimes Bowser is shown on a path to change his ways, often with Luigi playing a role in that transformation. For example, in some fanfictions, Luigi's kindness makes Bowser question his evil actions.
One interesting plot could be Bowser and Luigi being forced to team up against a common, greater evil. Maybe a new, more powerful villain emerges in the Mushroom Kingdom and they have to put aside their differences to save the day. This could lead to some comical moments as they try to work together, with Bowser's rough nature clashing with Luigi's more timid one.
One common theme could be adventure. Given that Luigi and Peach are from the Mario universe which is full of adventures, fanfics might center around them going on quests together, facing challenges, and relying on each other's skills.
Protection is also a frequent theme. Luigi is often portrayed as protective towards the reader in fanfics. He uses his skills and courage to keep the reader safe from various threats in the Mushroom Kingdom or other fictional settings. And of course, the theme of discovery. The reader discovers new things about Luigi and themselves as the story progresses.
One common theme could be friendship. Since Luigi and Tails are both sidekicks in their respective universes, stories might explore how they bond over their shared experiences of being in the shadow of more popular heroes like Mario and Sonic. Another theme could be adventure. They could go on adventures together, using their unique skills to overcome challenges.
One common theme is the idea of redemption. Many fanfics explore Bowser's potential for change and how Peach might be a part of that. Another theme is the breaking of stereotypes. Since Bowser is usually seen as a villain and Peach as a damsel, fanfics often play with these roles. For example, Peach might be the one to show strength and Bowser vulnerability.
Yoshi could also make an appearance in some bowser x luigi fanfics. He could be Luigi's sidekick or helper, adding an extra element of fun. Maybe Yoshi helps Luigi understand Bowser better or gets involved in some of their adventures, whether it's exploring a new part of the Mushroom Kingdom or dealing with other threats that come their way.
I'm not sure specifically as it could be a very fan - created and unique story. But generally, it might be a fan - made fictional work where Bowser, the villain from the Mario universe, kills Luigi. It could be a dark take on the usual Mario - related stories, perhaps exploring different themes like power, loss, or the unexpectedness of a major character's death in a fan - created scenario.
Well, you can try searching on some popular fanfic platforms like Archive of Our Own. There might be a variety of 'luigi x bowser fanfic' there. Just use the search function and type in the relevant tags.