Another plot could be centered around a tribute who has a hidden power or ability that they discover during the 4th Quarter Quell. This power could be something like telepathy which they use to communicate with other tributes secretly. They could then form a large alliance based on this secret communication and try to overthrow the Capitol's control over the games.
One idea could be to focus on a new set of tributes who form an unlikely alliance. They might be from different districts that have historical rivalries but realize they have more in common than they thought in the face of the Quarter Quell's harsh rules.
There are fanfictions that focus on the backstories of the tributes in the Quarter Quell. For example, a story that delves deep into the life of a particular tribute in District 12, how they grew up, what led them to be chosen for the Games, and how they feel about the Quarter Quell being different from the regular Hunger Games.
A mute tribute who uses sign language to communicate. This character would add an interesting dynamic as other tributes would have to learn to communicate with them in a different way. Their lack of voice could be seen as a weakness at first, but they could turn it into a strength, for example, by being able to move quietly and surprise their opponents.
One interesting concept could be the unique twists on the original Hunger Games premise. Maybe new types of arenas or challenges that are more extreme. For example, an arena that changes not just physically but also temporally, like having different time periods within it.
The Hunger Games First Quarter Quell fanfic often explores unique and darker aspects of the Hunger Games universe. It might focus on the special rules of this particular quell, like having double the number of tributes. Many fanfics in this category try to expand on the characters' backstories and their relationships in the face of this more intense and cruel version of the Games.
One idea could be a tribute who has a unique survival skill like being able to communicate with animals in the arena. They could use this to gather information about hidden resources or approaching threats.
One idea could be a revolution within the 100th Hunger Games. The tributes from different districts secretly plan to overthrow the Capitol's control over the games. They start by forming alliances not just for survival but to spread their message of resistance among the other tributes.
One idea could be focusing on a new type of arena. For example, an arena that changes based on the tributes' worst nightmares. This would add a psychological twist to the games.
One idea could be to focus on a new type of arena, like an underwater arena. The tributes would have to deal with things like limited air supply and underwater predators. Another could be a tribute from a previously overlooked district who has some unique skill, like being able to communicate with animals, which gives them an edge in the games.
Another plot could revolve around the Capitol's perspective. Show how the Gamemakers manipulate the Games, not just in terms of the physical challenges but also in influencing the tributes' mental states. For example, they could use propaganda within the Capitol to create more hype around certain tributes.