One interesting plot could be where Edward has to adjust to sudden fatherhood while still dealing with his alchemical pursuits. Maybe he discovers a new form of alchemy related to protecting his child.
In some fanfictions, the plot could revolve around Edward trying to find a way to give his child a normal life despite his own complex and dangerous past. He might struggle with how much of his alchemical world he should expose to the child. There could be a story where he has to team up with old friends or foes to protect his baby from a new threat that is related to the secrets of alchemy. Also, perhaps there's a plot where his child shows an early aptitude for alchemy, and Edward has to figure out how to teach and guide the child without repeating the mistakes of his own upbringing.
There could also be some original characters created just for the fanfiction. Maybe a new female alchemist who crosses paths with Edward and they end up having a relationship that leads to him becoming a baby daddy. Another possibility is an old acquaintance from his travels who resurfaces and they develop feelings for each other, resulting in a child.
Well, perhaps there's a plot where Edward, as a girl, has to keep his true identity a secret. This could lead to some really tense and comical situations. Like when his friends from before start showing different kinds of interest in him, not knowing it's really Edward. And he has to figure out how to interact with them without giving away his secret while also trying to find a way to turn back into his original self.
One interesting plot could be Edward trying to adapt to a world where alchemy doesn't exist in the same way. He might have to learn new forms of magic or technology to get by. For example, he could struggle with not having his alchemy skills to help him in combat or solve problems at first, but then gradually discovers new powers within himself in this new world.
One more great plot could be Naruto being trained by Edward in alchemy. Edward is a brilliant alchemist despite his young age. Naruto, with his eagerness to learn new things, would soak up all the knowledge. He could start creating his own alchemical ninja tools. For example, he could make a kunai that can transmute into different forms depending on the situation. And as he gets better at alchemy, he might start to question his own ninja way. Is it really all that different from alchemy? This internal struggle could add a lot of depth to the fanfiction.
Another theme could be innocence. Baby Edward is in a pure state, and fanfictions might explore how this innocence is gradually lost as he grows up and faces the hardships of the alchemical world. For example, a story could show how his first encounter with the darker side of alchemy starts to chip away at his innocent view of the world. It could be something as simple as seeing an alchemical experiment go wrong and realizing that there are consequences to the power he's so interested in.
Well, perhaps in the fanfiction, Snape discovers Harry has a special magical ability that is both a danger and a great potential. As a 'daddy' figure, he has to guide Harry in controlling it without alerting the wrong people. He might take Harry on secret excursions to practice this ability in safe places.
One possible plot could be Tucker and Ben getting into a friendly competition over a girl they both like in the fanfiction world. They might start off trying to outdo each other in impressing her, but then realize they value their friendship more.
One possible plot could be the challenges they face in raising a deaf baby in a world that is not always accommodating. They might have to learn sign language quickly and find ways to communicate effectively with their child from a very young age.
One possible plot could be about Edward Cullen's early days as a baby vampire. Maybe he shows some unique powers even as a baby in diapers, like being able to communicate telepathically with his family in a very basic way. Another could be his relationship with his parents in this infant state, how they take care of him and his special needs.
Well, one possible plot could be about the challenges of raising a child in the world of Twilight. Maybe the baby daddy is a vampire and they have to deal with the baby having some special abilities or needs because of its vampire heritage.