A unique plot. For example, if it combines the mystery of Babylon with the complex alchemy system of Fullmetal Alchemist in an unexpected way. Maybe it could explore a hidden aspect of Babylon within the Fullmetal Alchemist universe that hasn't been much explored before.
Some characters might be quite shocked or amused if they could read fanfiction about their own story. For example, Edward Elric would probably be very indignant at some of the out - of - character portrayals of himself. He's a proud alchemist and seeing himself depicted in a way that doesn't match his self - image would surely make him fume.
Yes, it is. The manga has a perfect balance of action, drama, and philosophy. The themes explored are profound, and the character growth is very satisfying.
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.
To make your Fullmetal Alchemist Brotherhood OC fanfiction stand out, give your OC a unique motivation. Instead of the typical 'find the Philosopher's Stone' goal, your OC could be seeking revenge for a personal loss related to alchemy. This will set them apart from the regular characters. Also, use vivid descriptions. Describe the alchemical transmutations in detail, like the glow, the sound, and the feel of the process. It'll make the reader more engaged. And don't be afraid to explore the darker aspects of the Fullmetal Alchemist Brotherhood world. Maybe your OC has to make some really tough moral choices, like sacrificing a friend for the greater good. That'll add a layer of complexity to your story.
Some characters might feel flattered. If the fanfiction portrays them in a heroic and positive light, especially if it emphasizes their good qualities like Edward's determination or Alphonse's kindness, they might secretly feel a bit of pride and be flattered by the author's view of them.