How about a young soldier who was forced into the time war? He starts off naive but as he experiences the horrors of the war, he becomes a key figure in trying to find a more peaceful solution. His journey from being a reluctant fighter to a peace - seeker could be really interesting to explore. Another option could be an ancient time - keeper who has the knowledge of how the time war started but has been in hiding. Now she decides to emerge to try and stop the war.
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.
Often, the main characters in 'the last great time war fanfiction' are those who have a significant impact on the outcome of the war. This could be powerful leaders from different factions. They might be characters with special abilities related to time. For example, a character who can freeze time in a small area to gain an advantage in battle. And sometimes, the main characters are not just the big - name heroes or villains but also the ordinary people who are trying to survive the chaos of the time war.
Finn is likely to be one of the main characters. He's a central figure in Adventure Time, so he'd probably play an important role in the fanfic related to the Great Mushroom War. Jake could also be there, as Finn's best friend.
A young and brash rookie pilot could be a great main character. He's full of enthusiasm but lacks experience. He has to learn quickly in the harsh reality of war. Maybe he idolizes an older, more experienced pilot who becomes his mentor.
A Dragonborn could be a great main character. They have unique abilities and could play a crucial role in the war, either by fighting directly or by using their influence. Another could be a powerful Thalmor agent, showing the other side of the conflict.
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.
There could be the last royal vampire themselves, of course. Then perhaps a loyal servant or advisor who has been with the vampire's family for generations. A hunter who initially wants to kill the vampire but then realizes they may be the key to something bigger is also a great character.
A turian officer could be a great main character. They are known for their military discipline and honor, and seeing the war from their perspective would be interesting.
There might be a young and determined trainer as one of the main characters in 'the great pokemon war fanfic'. This trainer could be on a quest to end the war and bring peace. Alongside him or her, there could be a group of unique Pokemon with special powers. There may also be an antagonist, perhaps a power - hungry trainer who started the war in the first place. And perhaps some side characters like a wise old Pokemon professor who gives advice to the main characters during the war.
It really depends on the specific fanfic. But often, there are survivors who become main characters. They could be ordinary people before the war who now have to be heroes. Maybe there's a young adult who has to lead a group of survivors to safety.
One idea could be exploring the untold stories of the soldiers on the front lines. Maybe focus on a small group who are trying to complete a secret mission during the chaos of the time war. Another could be delving into the origin of the time war and how it could have been prevented from the perspective of a time - traveling historian.