There are some great Milo x Melissa fanfictions out there. One popular one focuses on their adventures together outside of the normal chaos in their town. It shows their friendship evolving into something more special as they face challenges side by side.
A fanfic could explore a scenario where Zack has a crush on Melissa but is too shy to admit it at first. He tries to do nice things for her secretly, like leaving her favorite snacks in her locker. Eventually, Melissa catches on and they have a sweet moment where she tells him she likes him too.
The chemistry between Milo and Melissa in the show is great, and fanfiction expands on it. Their different personalities, Milo's Murphy's Law and Melissa's more practical nature, create interesting dynamics in the stories.
One idea could be that Milo and Amanda are paired up for a school project. Milo's usual Murphy's Law chaos ensues, but Amanda, instead of getting frustrated, starts to see the fun in it. They end up creating a unique project that no one else could have made, all while getting closer as friends and maybe something more.
They could have a shared love for something, like a particular type of music or a small local coffee shop. Every time they meet there, it's a sweet moment. Milo might accidentally spill coffee on himself because of his bad luck, and Amanda would laugh and offer to help clean it up.
The unpredictability. Just like in the show, Milo's bad luck can lead to all kinds of wild situations in fan fiction. It's exciting to see how different authors handle it.
One popular theme is the clash of different universes. For example, when Milo enters a world with different rules like in a crossover with Star Trek, the differences in technology and social norms create interesting scenarios.
Begin with a basic plot idea, such as Zack and Melissa getting lost in an abandoned part of town. Then, develop their characters further within this plot. Show how Zack might be scared but trying to act brave for Melissa, and how Melissa uses her intelligence to find a way out. Add details about their emotions, like the little glances they give each other when they think the other isn't looking. Also, don't forget to give the fanfic a satisfying ending, whether it's them becoming closer friends or something more romantic.
In 'Phineas and Ferb', Phineas and Isabella's love is a sweet and subtle story. Isabella clearly has a big crush on Phineas. She often tries to get his attention in cute ways, like when they are on their various adventures. Phineas, while not always fully aware of the depth of Isabella's feelings, really enjoys her company. Their relationship is part of the charm of the show, with little moments here and there that show their connection, like when they build things together or go on outings.