Perhaps a wealthy entrepreneur from a big city who decides to take over the small town for business reasons and ends up becoming the new overlord. They might start by buying up all the local businesses and gradually take control of the town's economy and politics. This character would be shrewd and calculating, using their financial resources to gain power.
It could be a young and ambitious wizard who has come to the town to assert his magical dominance.
A young prodigy who has been underestimated all his life. Fed up with being pushed around, he uses his intelligence and unique abilities to rise to power and become the world overlord.
The plot might involve the new overlord trying to bring about changes in the town. For example, they could be reforming a corrupt system or trying to modernize the town against the will of the traditionalists. There could be various sub - plots like making alliances with some of the townsfolk while facing opposition from others. This would create a web of relationships and power dynamics within the fanfiction.
The main characters could include the new goddess, an old wise man in the town who senses her power and tries to guide her, and a group of curious children who are not afraid to approach her. The children could bring out the more human side of the goddess.
I think Spider - Man would make an interesting main character. He's young and has a different perspective compared to the more experienced Avengers. His journey of growing up and becoming a more integral part of the team could be a central theme in the fanfiction. He also has his own set of personal problems like school and his relationships which could add depth to the story.
Perhaps a minor character from the original Fate series could be promoted to the main character. For example, a bystander in one of the battles who witnessed something extraordinary and was then drawn into the world of the Holy Grail War in a more central way in the 'a new fate fanfiction'.
It could be an ordinary person from our world, like a high school student. They're suddenly thrust into this new world and have to adapt. Their inexperience in this new environment can lead to many humorous and exciting situations.
One possible main character could be a vampire hunter. This hunter might initially be after the forgotten overlord but then realizes that there are greater threats in the vampire world and teams up with the overlord. Another character could be a witch who has knowledge about the spell that made the overlord forgotten and helps him to break it.
Maybe a young kid. Often in small towns, kids are underestimated but they might have a big heart and a lot of courage. They could discover something important that adults have overlooked and end up being the hero.
Naruto himself could be the main character. Since he's the protagonist of the original series, it would be natural to have him as the center of the fanfiction. He could be drawn into the new game world and have to use his unique skills and determination to succeed.
The main character would most likely be the new thief. They could be an original character created just for this fanfiction.