A popular choice could be a girl named Lily. She is curious and brave. When she becomes invisible, she decides to explore the secrets of her town that no one else has been able to. She might find out that there are some spooky things going on underground.
Maybe an older brother, Jake. He is responsible for his younger siblings. When they all become invisible, he has to figure out how to keep them safe and also how to reverse the invisibility. He could be the leader type, making plans and trying to outwit any threats that come their way.
One plot idea could be that the characters discover the invisibility power has a time limit and they have to complete a mission before they become visible again. For example, they need to retrieve a stolen artifact from a heavily guarded place.
One idea could be that the characters discover a magical object that makes them invisible. They then use this new - found power to solve mysteries in their town, like finding out who has been stealing from the local shops at night. They follow the thieves without being detected and finally expose them, becoming local heroes.
For creating interesting characters in this fanfiction, start with their backstories. If a character has a history of being overlooked or ignored, it gives a good reason for them to be interested in invisibility. For example, a shy student who has always been in the background. Their reaction to becoming invisible could be very different from someone who is more outgoing. They might be more cautious while the outgoing one could be more adventurous.
It could be a young and inexperienced warrior. They start off not knowing much about their haki ability but as the story progresses, they learn to master it. For example, a novice swordsman who discovers they can coat their sword and themselves in invisible haki, which gives them an edge in battles.
Maybe it's a scientist who was working on some kind of experiment and accidentally made themselves invisible. They would then use their scientific knowledge to try and reverse the situation while also having some adventures in their invisible state.
Fireheart would be a great main character for this. He's always been a brave and resourceful cat. His leadership skills would shine as he commands the other Warriors to get into positions. He could also be facing a moral dilemma during the events that make the story more interesting.
The main character in the 'invisible boy story' is the boy who has this unique quality of being invisible. He could be a young boy just starting to understand his power or a teenager dealing with the consequences of his invisibility in a more complex world. We might expect him to be curious, as his invisibility would open up a world of possibilities for exploration and discovery.
In H.G. Wells' 'The Invisible Man', the main character is Griffin. He is a scientist who discovers the secret of invisibility through his experiments.
The main character in the Invisible Woman story is Sue Storm. She is the one with the power of invisibility and force field creation.
It could be Bella. Since she goes through so much heartache in the original Twilight series, it would make sense for her to be the focus of a fanfiction about mending a heart. Maybe after the events with the Volturi or some other new threat, she is left broken and someone new comes in to help her heal.