A common theme is the clash of different power systems. Alchemy and magic are very different, and seeing how the characters from each world react to the other's power source is interesting. For instance, wizards might be amazed at the physical transformations possible through alchemy.
The exploration of different cultures is also popular. The Fullmetal Alchemist world has its own unique culture, and when combined with the rich culture of the Harry Potter universe, it can lead to some great storytelling. Characters might learn about each other's values, like the importance of family in Fullmetal Alchemist and the loyalty within Hogwarts houses in Harry Potter.
One interesting fanfic could be where the alchemist characters find themselves in the wizarding world of Harry Potter. They might use their alchemy skills in Hogwarts, which could create some really unique scenarios. For example, Edward Elric could try to analyze the magical properties of potions using his alchemical knowledge.
One common theme is the clash of different magic systems. Since Harry Potter has its own form of magic and Fullmetal Alchemist has alchemy, fanfics often explore how these two interact, whether it's in harmony or conflict.
One popular theme is the exploration of Envy's complex personality in the crossover. Since Envy is a homunculus with deep - seated issues like envy (obviously), in a crossover, it could be interesting to see how that plays out against new characters or new settings from the other fandom. Another theme could be the struggle for power. Envy often desires power in the Fullmetal Alchemist universe, and in a crossover, this could be magnified or redirected depending on the nature of the crossover. Also, themes of redemption are possible. Despite being a villain, Envy has moments of self - realization, and a crossover could explore if and how Envy could be redeemed in a different fictional context.
One popular theme is the exploration of Greed's complex character in the crossover setting. Since he has his own unique set of desires and moral ambiguities, it often leads to interesting storylines where he interacts with other characters from different universes or story arcs within the Fullmetal Alchemist world. Another theme could be the power dynamics. How does Greed's power compare and interact with the powers of characters from the crossover? It can create some intense battle or cooperation scenarios. Also, the theme of redemption sometimes shows up. As Greed is a character with a lot of 'greed' (obviously), his journey towards possible redemption or further fall into his vices can be a fascinating plot point in fanfictions.
One popular theme is the exploration of the deep and complex relationships between male characters. It might focus on their emotional bonds, like the loyalty and friendship that could potentially turn into something more romantic. Another theme could be the characters' struggle with their identities in a world that may not be fully accepting of their orientation.
One popular theme is the exploration of the characters' backstories. For example, there are many fanfics that delve deeper into Edward and Alphonse's childhood before the alchemy incident.
Well, a great plot twist might be that the characters from Fairy Tail end up in the world of Fullmetal Alchemist and are mistaken for some sort of alchemical creations. They then have to prove that they are not and in the process, they discover that their magic has some strange effects on the alchemy in that world. For example, Gray's ice magic could freeze alchemical reactions in unexpected ways. Another plot twist could be that the Gate in Fullmetal Alchemist has a link to the Fairy Tail's Celestial Spirit World. So when someone tries to open the Gate, they accidentally open a portal to the Celestial Spirit World instead, and all kinds of chaos ensues as spirits and alchemists meet for the first time.
Well, sometimes there's a plot twist where the Fuhrer is actually being controlled by an ancient alchemical force. This force has its own agenda and is using the Fuhrer's position to further its own goals, like gathering all the Philosopher's Stones in existence. It turns the whole political situation in the Fullmetal Alchemist world upside down and makes for a really engaging read.
In Fullmetal Alchemist and My Hero Academia fanfiction, the theme of power exploration is quite popular. Fans are interested in how the different powers in both series work together or contrast. Also, the idea of redemption is often explored. Some characters who made mistakes in the original series might get a chance to redeem themselves in fanfiction. Friendship is another important theme, showing how characters from different backgrounds form strong bonds.
One great 'Fullmetal Alchemist Scar Crossover Fanfic' is 'Scar's New Path'. It takes Scar on an adventure where he teams up with characters from another universe. The story is really engaging as it delves into Scar's character development in this new and strange setting.