Another fanfiction could involve Princess Peach getting lost in the Naruto universe. She could end up in Konoha and Naruto and his friends help her find a way back home. Along the way, Peach might learn some ninja ways and Naruto could learn about her diplomatic skills in dealing with different kingdoms.
First, you need to understand the characters well. For Naruto, his determination and his growth as a ninja are key aspects. For Princess Peach, her elegance and her role as a princess are important. Combine these elements in an interesting situation. For example, put them in a situation where they have to protect a common goal. Second, create a vivid setting. Whether it's a part of the Naruto world or a merged world of Naruto and the Mushroom Kingdom. Third, add some conflict. Maybe there's a villain who wants to use Princess Peach's power for evil in the Naruto world. This will keep the readers engaged.
One possible plot could be a crossover where Princess Peach is somehow transported to the Naruto universe. Maybe she has special powers that the Naruto characters are intrigued by. For example, her ability to float could be seen as a unique form of chakra control. Another plot could involve a love triangle between Naruto, a female ninja from the Naruto world, and Princess Peach, who has to adapt to the new world's customs of love and relationships. Or perhaps Princess Peach's Mushroom Kingdom is in danger and she seeks help from the ninjas in the Naruto universe, leading to an epic adventure of teamwork and discovery.
Well, a great way for them to collaborate in fanfiction would be to have them exchange cultures. Naruto could introduce Peach to the ninja way of life, like how they train and their code of honor. Peach could introduce Naruto to the more regal and courtly life in the Mushroom Kingdom. This exchange could lead to new ways of thinking for both of them and help them in their fight against whatever challenges they face. For instance, Naruto could use the Mushroom Kingdom's strategy of using power - ups in his battles in the Naruto world, and Peach could use ninja stealth in her own kingdom to outwit her enemies.
There might be a fanfiction where Princess Peach teams up with other Nintendo characters like Link. In this story, they combine their unique skills to defeat a new and powerful enemy that threatens both of their worlds. This kind of crossover fanfiction can be really exciting as it brings different universes together.
One common theme is redemption. Writers often explore the idea of Bowser being redeemed through his interactions with Peach. Another theme is the power of love, like if Bowser falls in love with Peach in a more sincere way rather than just lust for power. Also, friendship can be a theme where they become friends despite their differences.
In the fanfiction, Princess Peach was kidnapped during a grand celebration in the Mushroom Kingdom. The kidnappers were a race of powerful aliens who had long coveted the beauty and power of the Mushroom Kingdom. Mario and Luigi teamed up, along with Yoshi. They explored strange new worlds in search of Peach. Along the way, they discovered secrets about the aliens and found a way to defeat them, bringing Peach back safe and sound.
Princess Peach is diplomatic. She has to deal with various situations in the Mushroom Kingdom, from handling relations with neighboring kingdoms to dealing with the chaos that Bowser often brings. Her diplomatic skills help keep the peace and order in her realm, and she is always looking for ways to improve the lives of her people.
One common theme is the underdog love story. Since Luigi is often seen as the secondary hero compared to Mario, it's interesting to see him in a romantic relationship with Princess Peach. Another theme could be adventure, with them going on quests together.
Yes, there are some out there. You can try looking on fanfiction websites like Archive of Our Own. Just search for 'Princess Peach x Luigi' and you'll likely find a variety of stories written by different authors with different takes on their relationship.