Imagine a scenario where the Avengers are transported to the world of Fullmetal Alchemist. They would have to adapt to the different rules there. Captain America might be intrigued by the military structure in that world, while Thor could be interested in the concept of alchemy as it relates to his own magic. The two groups would have to learn from each other to find a way back to their respective worlds.
A crossover could involve the Homunculi from Fullmetal Alchemist being a threat that the Avengers have to face. The Avengers would be challenged by their unique abilities and the complex nature of the Homunculi. The alchemists might then team up with the Avengers, sharing their knowledge of the Philosopher's Stone and its power, which could be crucial in fighting the Homunculi.
Well, in some fanfictions, you might see Edward Elric from Fullmetal Alchemist teaming up with Eren Yeager from Attack on Titan. They could combine their unique abilities. Edward's knowledge of alchemy and Eren's Titan - shifting power could be used to take on common enemies. For example, they might face a new threat that is a combination of the Homunculi from Fullmetal Alchemist and some new type of super - Titan in the Attack on Titan world. And the different character dynamics, like Edward's hot - headedness and Eren's determination, would make for an exciting story.
In some fanfictions, the Sharingan is combined with alchemical knowledge. Picture Sasuke or Itachi using their Sharingan to analyze and perform alchemy more effectively. Or perhaps a character from Fullmetal Alchemist Brotherhood discovers the power of the Sharingan and tries to replicate it using alchemy. Additionally, the concept of the Gate of Truth from Fullmetal Alchemist Brotherhood in the context of the Naruto world could lead to some really deep and thought - provoking stories. For example, what if Naruto had to face the Gate of Truth? How would his beliefs and his journey as a ninja be affected?
One of the most popular crossovers might be those that focus on the magic systems. For example, combining the alchemy from Fullmetal Alchemist with the magic in Fairy Tail. Fans love to see how characters from both worlds would interact with these different power sources. Another popular type could be character - centered crossovers. Imagine Edward Elric from Fullmetal Alchemist teaming up with Natsu from Fairy Tail. Their different personalities and goals would create an interesting dynamic. Also, crossovers that explore the moral and ethical themes from both series are quite popular. Since both series deal with complex ideas about right and wrong, a crossover that delves deeper into these concepts can be very engaging for fans.
A plot could involve the Avengers trying to understand the concept of alchemy. Maybe Tony Stark becomes really interested in it and tries to incorporate it into his tech. Meanwhile, the Fullmetal Alchemist characters are in awe of the high - tech world of the Avengers. They could end up sharing knowledge and skills to take on a powerful foe that neither could defeat alone. For example, a powerful demon from the Fullmetal Alchemist world that has found a way to use advanced weaponry from the Avengers' world.
There probably are. Fanfiction writers often love to mash up different universes. In such a fanfic, Naruto could bring his chakra - based powers and blend them with the principles of alchemy from Fullmetal Alchemist. Maybe he'd use his Rasengan in a new way by incorporating alchemical transmutation circles. It would be a wild and creative concept.
Edward Elric and Tony Stark would definitely have some interesting interactions. Edward, with his knowledge of alchemy, would be both intrigued and a bit put off by Stark's high - tech gadgets. Stark, on the other hand, would probably see Edward as a brilliant but somewhat naive young scientist. They could argue about the best way to solve problems, with Edward pushing for more 'natural' alchemical solutions and Stark relying on his tech.
Another idea might be alternative endings. Fanfiction often plays with the concept of 'what if' things had gone differently. Maybe if Edward had not been able to regain his brother's body, how would he have coped and what new path would his life take?
Some popular crossovers in Fullmetal Alchemist D Gray Man fanfiction include scenarios where the alchemy of Fullmetal Alchemist is used to understand or enhance the Innocence in D Gray Man. Also, the idea of characters from one series training with characters from the other. For instance, Kanda from D Gray Man might train with the Elric brothers. This allows for a great exchange of fighting styles and ideologies between the two universes.
Another powerful combination could be Scarlet Witch and Roy Mustang. Scarlet Witch's reality - warping powers and Roy Mustang's ability to control fire through alchemy. Together, they could create massive and unique attacks. The Scarlet Witch could manipulate the fabric of reality to enhance Roy's fire - based alchemy, making it even more destructive and unpredictable.
One idea could be an OC who is a foreign alchemist with a unique form of alchemy based on their homeland's culture. For example, an alchemist from a desert region who uses sand-based alchemy. Another could be an OC that has a special connection to the Homunculi, not as an enemy but as someone trying to understand and redeem them. Maybe an OC that was experimented on by the same people who created the Homunculi and has some shared traits.