Daenerys Targaryen might also be a main character in such fanfiction. An angel could appear to her, perhaps convincing her to use her dragons in a different way. Or the angel could be a part of her entourage, secretly influencing her decisions and adding an extra layer of mystery to her already complex character arc.
In some fanfictions, Jon Snow could be a central figure when combined with the angel elements. Imagine an angel bestowing upon Jon some new powers or knowledge that helps him in his fight against the White Walkers. And there could be a female angel character who has a special bond with Jon, guiding him not just in his battles but also in his personal growth as a leader.
It could be a new character created specifically for the fanfiction. This character might be an outcast from a noble house who receives the call and is thrust into the center of the power struggles in Westeros.
Often, the Gravewalker themselves is a main character. They usually have a mysterious past and special abilities. There could also be characters from the original Game of Thrones series who interact with the Gravewalker. For example, Jon Snow might cross paths with the Gravewalker and they could form an alliance or be at odds. Daenerys could also be involved, perhaps seeing the Gravewalker as a threat to her claim to the Iron Throne.
Often, there could be a young and idealistic character who leads the uprising. Maybe a bastard son or daughter of a noble house who has seen the injustice in the system. Another could be a former slave who has escaped and now wants to free all his fellow slaves. And there might be a maester who has been exiled from the Citadel for his radical ideas and joins the uprising.
A young and clever maid in the service of one of the noble families in Queensgate could be a main character. She might be privy to a lot of secrets and use her wits to navigate the dangerous political waters. Maybe she overhears a plot against her master and has to decide what to do about it.
One main character could be a genetically - enhanced human who has special abilities, like Arya Stark's skills in the original. She could be on a mission to avenge her family who were killed by a powerful space - faring clan. There could also be a powerful warlord from a distant star system, a bit like Ramsay Bolton, feared for his cruelty and thirst for power. The interactions between these diverse characters would drive the story forward in this space - based Game of Thrones fanfiction.
Cinderella would be a central figure. For the male lead, it could be a young and noble - hearted character like Robb Stark. He has the charm and leadership qualities similar to a prince. The stepmother could be a power - hungry noblewoman, like Cersei Lannister in some ways. The stepsisters could be her daughters, who are jealous of Cinderella's beauty and the attention she gets from the young lord. And then there could be other 'Game of Thrones' characters like Tyrion Lannister as a side character providing some wisdom and humor.
Myrcella is obviously one of the main characters. Since it's a fanfiction centered around her, she would be the focal point of the story.
Well, the main characters are obviously Daenerys and Daario. Daenerys is a powerful and complex character. She is a queen with dragons and a strong will to claim the Iron Throne. Daario, on the other hand, is a skilled and somewhat roguish fighter who is attracted to Daenerys and becomes one of her important allies.
Most likely the Starks would be main characters. Jon Snow, as he has strong ties to the North and is a natural leader. Sansa Stark too, with her new - found political acumen. Arya could also be important as she has her own brand of justice she might bring to the North's cause.
Arya Stark could be a main character. She could use her skills as a Faceless Man to infiltrate the enemy's camp before a big battle and gather intelligence. Her ability to change her appearance would give her an edge in spying and sabotage operations during the battle.