A maester who travels to Skagos to study its history and legends. He would be an outsider looking in, and his scientific and academic approach to understanding the island and its people would provide a different perspective. His interactions with the Skagosians, who may have a more superstitious and primitive view of the world, could lead to many interesting storylines.
A Skagosian outcast. He could have been banished from his tribe for some reason, like not following their brutal traditions. This character would be interesting as he would be an outsider even in his own land at first, and his journey to either regain his place or find a new one could be full of adventure and self - discovery.
A female warrior from Skagos. In a world dominated by male characters in 'Game of Thrones', a female Skagosian warrior would be a refreshing and strong main character. She could be fighting against the traditional gender roles within her own society while also getting involved in the larger events of Westeros, perhaps even having an impact on the outcome of the power struggles.
Arya Stark could be an interesting main character as a summoner. She already has a lot of skills like stealth and combat. If she were a summoner, she could summon the spirits of those she has killed to either help her in battles or to gather intelligence. It would be a new twist on her character.
Bran Stark could also be the main character. His new powers as the Three - Eyed Raven give him a whole new perspective. He could be the one to guide Westeros into a new era. He could use his knowledge of the past and his ability to see things that others can't to make decisions that would shape the future of the Seven Kingdoms.
Melisandre could be a main character if you consider her as a kind of warlock. She has her strange powers, like seeing the future in the flames. You could write a fanfiction exploring her past, how she became a red priestess and gained her powers, and her further adventures in Westeros, perhaps with her using her powers in different ways than in the original series.
A possible plot could be centered around a Skagos native who has a prophetic dream about the future of Westeros. This person then embarks on a journey to find someone who can interpret the dream correctly. Along the way, they encounter various characters from the 'Game of Thrones' series and get involved in their own mini - power struggles, all while trying to fulfill their quest related to the prophetic dream.
It could be a Targaryen descendant. Since the Targaryens were known for their connection with dragons, it would make sense for one of their descendants to be the main character in a story about the last dragon.
It could be a young apprentice wizard who has just discovered his powers. He is eager to prove himself and protect the North from all the threats it faces.
Daenerys Targaryen could also be a main character in an emperor - like role. She already had a strong claim to the Iron Throne and was a powerful leader. In a fanfiction, she could fully embrace her role as an all - powerful emperor, perhaps even uniting the Seven Kingdoms under her rule in a more forceful way than in the original series.
Maybe an outcast noble. They've been shunned by their family for their interest in the dark arts. So, they embrace necromancy fully and aim to use it to take revenge on those who wronged them. They start by raising the dead of their family's enemies, and gradually build an army of the undead. Their journey would be filled with self - discovery and moral quandaries as they delve deeper into the world of necromancy.
It could be a new female character. Maybe a commoner who rises to power by her own determination. She could be from a small village and through her skills, like her ability to read and write, which is rare for commoners in the 'Game of Thrones' world, she catches the attention of the nobles and starts to make a name for herself in the political arena.
Arya Stark could be a great main character in such a fanfiction. Imagine if she discovered she had latent sorcerer abilities. She could use her skills in disguise along with magic to infiltrate the most dangerous places. For example, she could magically change her appearance even more effectively than she does with her face - changing skills, and get closer to her enemies to take revenge.