Gil - galad, the Elven king, is another main character. His elven wisdom and power were important in the fight against the enemy. His interactions with the human and dwarf leaders in the alliance would be a key part of the story, as they had to work together despite their differences.
It could be really interesting. Fanfictions often explore different aspects of the original concept. Maybe it focuses on the relationships between different characters during the war, like the alliances they form and the betrayals that might occur.
One idea could be exploring the backstories of the minor characters in the War of the Last Alliance. Maybe there was a young soldier who had a secret love interest back home and his journey was not just about the war but also about getting back to her.
You could write about a love story set within the context of the war. For instance, two soldiers from opposing sides who fall in love. Their relationship would be filled with secrecy, danger, and moral dilemmas as they try to navigate their feelings while being part of the war.
As we know very little about the 'Alliance War of Thorns Story', the main characters could be a range of people. There might be a heroic general who leads the alliance into battle. There could also be a wise strategist who tries to navigate the complex political and military situations. And perhaps there are some characters from different factions within the alliance who have to overcome their differences to fight together.
It could be a group of young adventurers. For instance, a brave warrior, a clever mage, and a stealthy thief who form the core of the secret alliance.
The main characters are likely to include Aang, who will be at the center of any attempts to keep the peace. Zuko, who has the huge task of reforming the Fire Nation. Katara, who could use her waterbending and her wisdom to heal the wounds of the war, both physically and emotionally. Then there's Sokka, whose intelligence and creativity will be needed to solve the various problems that arise in the post - war world. Also, Appa and Momo will probably be around, adding a bit of their own charm to the story as Aang's loyal companions in this new phase of their lives.
A time - traveling rogue could be a great main character. He's not really on either side of the war but is just trying to survive and make a profit in the chaos. Maybe he stumbles upon a powerful time - based weapon and has to decide what to do with it.
I'm not sure specifically as I haven't read it. But it's likely to have soldiers as main characters. They could be from different backgrounds, with different motives for fighting.
I'm not sure specifically as it depends on the fanfic. But it could be the leaders of the alliance, perhaps a human general or an alien diplomat.
Obviously, Harry would be one of the main characters. He is the one making the decision to break the alliance, so his character development would be central to the story.