One common plot idea is exploring his past more in - depth, like his time at the military academy. It could show his relationships with other students and how he developed his skills and personality.
Some fanfictions also focus on his relationships in a more romantic way. Maybe he falls in love with a character that was only briefly in the original series, or his relationship with an existing character is explored from a different angle, like a deeper emotional connection that was not fully shown in the original.
Another interesting plot is a 'what - if' scenario. For example, what if he made different choices during certain battles? How would that change the course of the story and his relationships with other characters? It can be really exciting to see an alternate version of events.
A really interesting plot could be a time - travel scenario. Chimera Mustang and Edward Elric get sent back in time to a crucial point in the history of alchemy. They have to navigate this new - old world while also trying not to change history too much. This would be full of opportunities for them to interact with past versions of characters and maybe even prevent some future disasters.
One interesting plot idea could be that Roy and Edward have to team up on a secret mission that involves alchemy and military strategy. They start off not getting along well because of their different personalities and approaches, but as the mission progresses, they learn to respect each other and become friends. Another idea is that Edward discovers a new form of alchemy that Roy is interested in for military use, and they have to work together to keep it from falling into the wrong hands.
Another plot could involve Edward making new friends in the town. These friends could be outcasts like him, and together they form a sort of club. They could then work on projects to beautify the outskirts of the town that have been neglected.
One idea could be exploring Edward Mordrake's backstory more in - depth. Maybe his life before the whole 'two - faced' situation, his family, and what led him to become the tragic figure he is. Another could be a modern - day encounter with someone who has a special ability to communicate with him.
One idea could be that Edward, as a cop, is assigned to protect a key witness. During this time, he discovers a complex web of secrets and has to fight against both the criminals who want to silence the witness and some corrupt colleagues. Another plot could be Edward investigating a series of mysterious murders in the city where all the evidence points to a supernatural force. He has to overcome his disbelief in the supernatural to solve the case. And also, Edward could be a rookie cop who gets involved in a big drug - bust operation and has to prove himself to his more experienced partners.
One idea could be that Harry and Edward meet in a magical forest that exists between the wizarding world and the vampire realm. They initially mistrust each other but then find out they have a common enemy and have to team up to defeat it.
One interesting scenario could be Roy Mustang teaching Edward Elric more about military politics. Since Mustang is well - versed in that area and Edward, being young and brilliant, could learn a great deal. Another could be Mustang helping Edward deal with the emotional aftermath of his alchemy - related traumas. Edward might open up to Mustang in a father - son type of relationship and start to heal.
One idea could be that they go to a secluded beach and discover a hidden cove with magical properties. Another could be a trip to a foreign city where they encounter a vampire from an ancient lineage. And they might also go on a mountain vacation and face some dangerous supernatural creatures there.
Perhaps in the fanfiction, there is a parallel universe where Kim and Edward are from different social classes in a more modern - day setting. Kim is a famous artist who is intrigued by Edward's unique sculptures made with his scissor hands. They start to collaborate on art projects, and gradually fall in love as they break down the barriers between their different worlds.
A third plot idea is that Giselle and Edward accidentally swap personalities. Giselle becomes more reserved like Edward used to be, and Edward becomes more bubbly like Giselle. This would lead to a series of hilarious situations as they try to adjust to their new personalities while still ruling Andalasia. Their friends and subjects would be quite confused at first but would eventually help them get back to normal.