To write a good fma crossover fanfic, start by choosing the right crossover. It should be something that has potential for interesting interactions. For instance, if it's an FMA and Bleach crossover, think about how alchemy and soul reaper powers could interact. Research both fandoms thoroughly. Look at their cultures, technologies, and power systems. When writing the story, focus on the emotions of the characters. Show how they react to this new and strange crossover world. Use vivid descriptions to bring both universes to life in the fanfic. And don't forget to proofread and get feedback from other fans.
A really interesting fma crossover fanfic idea might be with the world of Fullmetal Alchemist and the Lord of the Rings. Imagine the Elric brothers in Middle - earth, facing the challenges there. They could use their alchemy skills in a world filled with magic, elves, and orcs. It would be a very unique combination as the concepts of alchemy and the magic in Middle - earth are quite different.
One idea could be that Naruto characters are somehow transported to the FMA world and have to adapt to the rules of alchemy. For example, Naruto might be intrigued by the concept of equivalent exchange and try to apply his ninja way to it. He could learn alchemy and use his chakra in unique ways to manipulate it.
One idea could be to have the characters from 'Fullmetal Alchemist' (FMA) end up in the 'Ouran High School Host Club' (OHSHC) universe. For example, Edward and Alphonse could enroll in Ouran High School. Edward's short temper and Alphonse's gentle nature would create interesting interactions with the host club members. They could get involved in the club's activities, like the commoner's day event, and bring their alchemical knowledge into this new world.
One possible fanfic could be 'Ed's Magical Adventure in Hogwarts'. In this, Ed uses his alchemical skills in the wizarding world. He might teach the students about different ways of manipulating matter, which is quite similar to magic in some aspects. For example, he could show how to transform basic elements, just like a transfiguration spell.
Well, if Ed was a teacher in a FMA - Harry Potter crossover fanfic, it could be really interesting. He might teach alchemy in Hogwarts. Imagine him trying to explain the principles of alchemy to the wizards, who are used to magic in a different way. He could get frustrated with the lack of understanding at first, but eventually find students who are really into it. He might also have some run - ins with the more traditional teachers who don't quite understand his methods.
For the FMA characters in the OHSHC world, you can show how they adapt to the new social norms. Edward, for instance, might initially be frustrated with the elaborate social games in OHSHC but gradually learn to play along. You can also focus on how their goals change. Maybe they start off trying to find a way back to their own world but then become invested in the problems of the OHSHC characters. For the OHSHC characters in the FMA world, their charm could be used in different ways. Tamaki could try to use his charm to negotiate with the military in FMA.
In a crossover fanfic, Ed might teach a class on the practical applications of energy manipulation. Alchemy in FMA is all about understanding and controlling energy. He could show the Hogwarts students how to use their magic in more efficient and creative ways, similar to how he uses alchemy. For instance, he could teach them how to focus their magic energy for a more powerful spell, just like he focuses his alchemical energy for a difficult transmutation.
I think Naruto himself would be really interesting. His positive and determined attitude would contrast with the often darker and more complex world of FMA. He could bring his unique brand of ninja spirit and try to make friends with the characters in FMA. His ability to use chakra and his various jutsu would also create some really cool interactions when faced with the alchemists and their powers.
Often, these fanfictions blend the dark and complex world of Fullmetal Alchemist with the idea of 'lust' which could be in terms of a character's desires or a new, alluring force in the story. They might also explore different character relationships and how 'lust' can either strengthen or disrupt them.