Mario would definitely be a main character. Since Luigi is his brother, he would be the one most concerned about Luigi's transformation and would do everything he could to help him. Princess Peach could also be a main character. She might offer her castle as a safe place for baby Luigi and use her resources to find a solution. Toad could be there too, helping Mario with taking care of Luigi and providing useful information about the kingdom that could lead to reversing the spell.
A fanfiction that stands out is 'When Tails Met Luigi'. In this story, Tails accidentally lands in Luigi's world while testing a new invention. They start off a bit wary of each other but soon realize they can help one another. The story has great character development and a fun, engaging storyline that keeps you reading.
No. Mario and Luigi are typically seen as a friendly and loving brother duo in the Mario franchise. Depicting abuse between them in fanfiction is not in line with the positive values associated with the characters.
Another reason could be that in the official Mario games, Luigi is often seen as the secondary character to Mario. In fanfiction, making him cry can be a way to give him more depth and a chance to be the center of attention. It gives writers the opportunity to develop his character further and show his more emotional side, which fans might find really appealing.
I'm not entirely sure specifically what 'luigi snaps fanfiction' is about without more context. It could potentially be a darker take on Luigi's character where he snaps under some sort of pressure, like the constant threat from the villains in the Mushroom Kingdom. It might explore his psyche and how he deals with things differently than his more famous brother Mario.
Their relationship could develop through shared interests. For example, if they both have an interest in exploring the more mysterious parts of the Mushroom Kingdom. They could start going on adventures together, and as they face challenges like tricky terrains or new enemies, they rely on each other and grow closer.
The relationship could start with Luigi being a shy admirer of Peach. He might do small things for her like bringing her special flowers from the Mushroom Kingdom. Peach starts to notice Luigi's thoughtfulness and begins to seek his company more often. As they spend more time together, they discover they have a lot in common, like their love for the peaceful parts of the kingdom. This mutual understanding leads to deeper feelings and eventually their decision to get married.
Peach could be an important character. As a friend of Daisy and a princess in the Mushroom Kingdom, she could offer her wisdom on raising a child. Also, Yoshi could be there. Yoshi is always friendly and could be like a protector for the baby, watching over it when Luigi and Daisy are busy.
Mario could be a great addition. Since Luigi is Mario's brother, his presence could add some family - related drama or comical moments. Sonic could also be included. As Tails' friend, Sonic's brash and confident personality would contrast well with Luigi's more timid nature.