I think Izumi Curtis would be really interesting to include. She was their teacher, so she has a lot of knowledge and wisdom to share. Her strict but caring personality would contrast well with Ed and Al. Also, Ling Yao could be in the story. His own quest for immortality and his wily nature could lead to some really exciting plot twists when combined with Ed and Al's story.
Maes Hughes is also an excellent choice. His warm - hearted nature and loyalty could provide some emotional depth. He could also offer valuable information or resources to Ed and Al. And of course, Scar. His complex backstory and his own brand of alchemy would make for an interesting dynamic with Ed and Al. He could start as an enemy but then turn into an ally as they discover they have common goals.
Winry would be a great addition. She has a deep connection to Ed and Al, and her skills as a mechanic could play an important role in the story. Another good character is Roy Mustang. His military power and knowledge of alchemy could add a lot of drama. He could be either an ally or an obstacle depending on the plot.
One possible aspect to consider in this fanfiction could be the character development of ED and AL. Their relationship in the original series is very deep and in the fanfiction, it might explore new dimensions of their bond, perhaps in different scenarios or alternate universes.
The fanfiction might introduce new storylines that are not in the original series. It could be something as simple as a day in their lives that was never shown before, or a more complex plot involving new villains or challenges. And seeing how ED and AL react to these new elements is part of the allure.
One idea could be a story where Ed and Al find a way to reverse their alchemical mistakes in a completely unexpected way. Maybe they encounter a long - lost alchemist who has a unique method. Another plot could be them traveling to a parallel universe where their roles are reversed. For example, Al is the one who is more assertive and Ed is more reserved.
For Ed, being married to Al could make him more empathetic. He's used to being a bit of a lone wolf, but now he has to consider Al's feelings and needs all the time. This could lead to him being more understanding of others as well. Al's personality might develop in a way that he becomes more of a leader. He and Ed are a team, but Al could start taking the lead in certain situations, especially when it comes to diplomatic matters in the alchemical community. Their marriage would be a journey of mutual growth, where they both learn from each other and become better versions of themselves.
One plot idea could be that they discover a way to reverse their alchemical transformations through a series of adventures together as a married couple. They might travel to different parts of their world, facing old enemies who now have new motives against them as a united front. Another idea is that they start a school for alchemy, passing on their knowledge while also dealing with the politics of the alchemy world.
In a fanfiction, Ed and Winry could go on a journey together. Maybe they're searching for a rare automail part that could enhance Ed's current prosthetic. Along the way, they face many challenges. They rely on each other's skills - Ed's alchemy and Winry's mechanical knowledge. Their relationship deepens during this adventure as they learn more about each other's dreams and fears.
In a fanfiction, perhaps there's a misunderstanding between Ed and Winry. Winry thinks Ed has feelings for another girl because he's been spending a lot of time with a female alchemist. Ed is oblivious to Winry's concerns at first, but when he realizes, he has to find a way to prove to Winry that she's the only one for him.
Another reason is the 'forbidden' aspect of their relationship. Envy is a Homunculus, and Ed is a human alchemist. In the world of Fullmetal Alchemist, such a relationship would be frowned upon. But in fanfiction, this taboo nature makes it all the more exciting to explore. It allows writers to break the norms of the original story and create unique and interesting storylines that involve the two characters defying the odds and coming together in different ways.
In a fanfiction like this, Ed dressing as a girl could be part of a bet. His friends might have dared him to do it, and at first he's all about proving them wrong and showing he can pull it off. But then he realizes that wearing a girl's dress comes with its own set of challenges, like walking in different shoes or dealing with long hair (if he has a wig). This could make for an interesting character - development story.
There are fanfics that delve into their childhood memories and how those experiences shaped their relationship. For example, the times when Ed was getting his automail fixed by Winry's family. These fanfics often add more depth to their bond and show how their feelings for each other grew over time. It can be really interesting to see different interpretations of their relationship in these fan - created stories.