The Asari Commanders are often quite memorable. Their long lifespans give them a unique perspective on the war, and their biotic abilities make them formidable on the battlefield.
Some Turian soldiers are also very memorable. Their strong sense of honor and discipline in the face of war is something that stands out. They are often portrayed as being loyal to their cause and comrades, no matter what.
There could be a human character who rises from being a nobody to a great war hero. This character might start as a simple grunt but through their courage, wits, and a bit of luck, becomes a symbol of hope for the human forces during the First War. Their journey from obscurity to heroism can be a very engaging story.
Anderson is often a popular choice. He's a well - known human character from the Mass Effect series and his military experience and leadership skills make him a great fit for stories set during the First Contact War. Another popular one is Saren. Even though he becomes a villain later, his skills and his role in the Turian military during the early days can be an interesting aspect to explore.
Shepard is often a very popular character in such fanfiction. Since Shepard is a well - known and respected figure in the Mass Effect universe, they can play a crucial role in the civil war, either as a mediator or as a combatant on one side. Garrus is also popular. His combat skills and loyalty make him a great asset in any civil war - related story.
I'm not entirely sure about all the main characters specifically, but it would likely include human military leaders and Turian commanders as they are the two sides at war.
A human scientist could also be a main character. The scientist could be part of a team studying the Turians' technology during the war. They might accidentally discover a way to end the war but have to convince both sides to trust them. Their knowledge of science could be the key to peace, but they face a lot of opposition from military leaders on both sides.
It could be a mix of characters from both universes. There might be classic WW2 soldiers like Patton or Eisenhower, but with a Mass Effect twist. Maybe they have some kind of exposure to Mass Effect technology that gives them special abilities. Also, there could be Mass Effect characters like Shepard who are somehow transported to the WW2 era.
In Mass Effect fanfiction about the First Contact War, it often explores the initial violent encounter between humans and the Turians. One aspect could be the cultural misunderstandings that led to the war. For example, the Turians' strict military discipline clashed with humanity's more diverse and sometimes chaotic approach to warfare.
Popular characters in Halo Mass Effect Fanfiction include some of the elites from Halo. Their honor - based culture can create interesting interactions with Mass Effect characters. Thane Krios from Mass Effect is also a character that often shows up. His assassin skills and complex backstory can add depth to fanfiction stories. And then there's the Flood - infected characters which, while not traditional 'popular' in the sense of heroes, can create really dark and interesting plotlines in fanfiction.
Shepard is definitely one of the most popular. As the main character of the game, fanfiction writers love to put Shepard in various new situations. Garrus is also very popular. His loyalty and his badass sniper skills make him a favorite. And Tali, with her unique appearance and interesting backstory, is often a central character in many fanfictions.
Aria T'Loak from Mass Effect could also be a great character to feature. Her shrewdness and control over Omega could translate well into the power - struggle - ridden world of Gears of War. She could form alliances or rivalries with the different factions in the Gears of War universe.
Shepard could be a main character. Given their experience in uniting different species and facing great threats, they would be a natural fit in a world war scenario. They could lead a coalition against a new enemy.