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 interesting concept could be the exploration of post - war societies. In great mushroom war fanfic, we might see how different groups have rebuilt or are struggling to rebuild. Another concept could be the origin of the war itself, like what led to such a catastrophic event. Also, the evolution of characters in this war - torn setting is fascinating, as they adapt to survive and find meaning in a desolate world.
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.
One idea could be exploring the origin of the Mushroom War in more detail. Maybe there are some hidden causes or events that led to it. Another could be focusing on the characters' lives before the war and how it changed them. For example, how Finn's family was affected.
The Great Mushroom War in Adventure Time is a really interesting part of the story. It's this huge event that happened in the past. It was so destructive that it changed the world completely. The land was scarred, and new species emerged from the chaos. We know that there were probably different factions fighting, but we don't get all the details. There are hints that there was some sort of scientific and magical arms race that led to the war. The characters in the present day, like Finn and Jake, are living in a world that's still trying to recover from this cataclysmic event. They find old bunkers, strange weapons, and other things that are remnants of the pre - war civilization, which gives us little glimpses into what the world was like before the Great Mushroom War.
A young and naive character who grows throughout the story can also be very memorable. They start off being scared and helpless but through their experiences in the post - war world, they become a strong and resourceful individual. Their transformation is inspiring and makes them stand out among the other characters.
One interesting plot idea could be exploring the aftermath of the war from the perspective of a young survivor. They might be on a journey to find a rumored safe haven, facing various mutated creatures along the way.
In the context of The Great Mushroom War story in Adventure Time, Finn and Jake are key. Finn, as the human boy, and Jake, his shape - shifting dog friend, are constantly coming across remnants of the war. Marceline, the vampire, also has a connection. She's old enough to have some memories or knowledge about the events of the war. Plus, there might be some other characters from the past that are only hinted at, who were involved in the power struggles that led to the Great Mushroom War.
Finn and Jake would be obvious choices. Their courage and friendship could be put to the test in the harsh post - war world. They might be on a mission to help the survivors or to uncover the secrets of the war.
You could write a fanfic about how the Mushroom War affected the magical elements in the Adventure Time world. Maybe the war disrupted the balance of magic, and certain characters are on a quest to restore it. They might encounter strange new magical creatures or phenomena that were born out of the chaos of the war.