To create a compelling OC homunculus, start with its motivation. What does it want? Is it power, acceptance, or something else? Then, think about its relationships. Does it have an ally among the human alchemists or is it at odds with all of them? Also, consider its powers. Make them interesting and related to the Fullmetal Alchemist lore. For instance, it could have the ability to manipulate a specific type of metal in a way that's different from the main characters. And don't forget to give it flaws. A homunculus that is too perfect won't be as engaging.
The Culexus Assassin Homunculus can be a really interesting element in fanfic. In some fanfics, it might be depicted as a mysterious and powerful being. It could be used to create complex plotlines, perhaps as a tool for an evil mastermind or as a misunderstood creature trying to find its place in the fictional universe.
In fanfiction, the possibilities are nearly endless. Regarding Edward Elric becoming a homunculus, it could be a very interesting concept. If he were to become one, it would completely change his relationship with other characters. For example, his brother Alphonse might react in a very different way. Also, Edward's own view of himself and his abilities would be transformed. His struggle with his new form, if it were to happen, could be a central theme in the fanfiction. Maybe he would try to find a way to reverse the process, or perhaps he would embrace his new existence as a homunculus. It all depends on the creativity of the fanfiction author.
In fanfic, it's often portrayed as a very stealthy character. Its assassin - like nature is emphasized, and it can move through the shadows undetected. This makes it a great addition to stories that involve espionage or secret missions.
One possible plot for 'naruto is a homunculus fanfiction' is that Naruto is secretly a homunculus created for a specific purpose, say, to be a weapon in a long - forgotten war. As he grows up, he starts to show signs of his homunculus nature, like enhanced physical abilities or strange powers that are not part of normal ninja training. He then has to figure out who made him and why, while also dealing with the fact that some in the ninja world might see him as an abomination. Along the way, he could meet other homunculus - like beings or discover ancient secrets about the connection between homunculus creation and the ninja arts.
One common theme is identity. Since the homunculi are in a new crossover world, they often question who they are and their place in this new setting. For example, in many crossovers, they might compare themselves to the new characters they meet.