Who could be the main character in a 'one guy enters all female universe fanfic'?

The plot could involve the guy initially being shocked by the all - female universe. He might struggle to fit in at first, facing cultural differences. Then, he could form unique friendships with some of the female characters. Maybe he helps them solve a problem that only his different perspective can address.

One common theme could be the power dynamics. With one guy in a world full of females, the way power is distributed and negotiated can be an interesting theme. Maybe the guy has some special ability or role that gives him a certain status among the females.

Perhaps the main character is a young man who is on a quest for something. He enters the female world by accident and has to deal with all the challenges it presents while still trying to pursue his original goal. He could be a scientist looking for a rare element, and in the female world, he has to figure out how to communicate and work with the locals to continue his search.

I'm not sure of specific 'one guy all female universe fanfic' works off - hand. But you can try searching on fanfic platforms like Archive of Our Own. There are often various themed fanfictions there, and by using relevant tags and keywords, you might be able to find what you're looking for.

It could also be Harry Potter. Imagine Harry meeting the science guy and learning about a whole new way of looking at magic through scientific eyes. So Harry could be the main character, but the story would revolve around his interactions with the science guy.

Maybe one of the primordial deities, like Gaea, could be the main character. The fanfic could explore her thoughts and actions as she was one of the first beings. It could show how her relationship with other primordial deities influenced the future of the universe, and how her actions in the beginning set the path for events that would unfold much later in the Percy Jackson series.

A Slytherin prefect could be the main character. They are used to being in a position of authority and responsibility. When the potion turns all the Slytherin males into females, they take charge. They have to keep the Slytherin house in order, deal with the reactions from other houses, and also find a way to reverse the potion's effects while still maintaining the reputation of the Slytherin house.

It could be a reversed Darth Vader. Instead of being a Sith Lord on the dark side, he could be a powerful Jedi who uses his skills to fight against the new 'evil' which was once good. He might have a red lightsaber still, but it represents the new 'light side' in this reversed universe.

A Hufflepuff prefect could be the main character. They are responsible for maintaining order within the house and could be caught in the middle of a power struggle between the different houses in this alternate universe. They would have to use their Hufflepuff traits to resolve conflicts and keep the peace in Hogwarts.

A powerful, ancient sorcerer could be a great main antagonist. This sorcerer could have been locked away for centuries but has now broken free and wants to take over the universe from the Master of the Universe. He could have dark magic that the Master has never faced before.