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.
You can try searching on popular fan - fiction websites like Archive of Our Own (AO3) or FanFiction.net. Just type in the exact phrase 'bowser kills luigi fanfic' in their search bars and see if any relevant stories come up.
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.
One possible motive could be power. Bowser has always been after power and ruling the Mushroom Kingdom. Maybe in this fanfic, Mario was getting too much influence or was about to discover something that could undermine Bowser's power, so he decided to kill him.
I'm not entirely sure specifically what that particular fanfic is about without reading it. But generally, if it's a 'bowser kills peach' fanfic, it might be a darker take on the Super Mario universe where Bowser manages to defeat Princess Peach, perhaps exploring different consequences and reactions within that fictional world.
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.
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 if it's extremely popular. While the idea of a major character like Peach being killed by Bowser is a bold and interesting concept, it might not be to everyone's taste. Some fans prefer more positive and traditional storylines in the Mario fanfic world.
Well, it completely flips it. Usually, Mario is the one who overcomes Bowser. But here, with Bowser killing Mario, it makes Bowser seem more menacing and powerful than ever. It also takes away the hope that the Mario universe usually has, as Mario is the hero who saves the day.