Maybe the Capitol decides to change the rules completely for the rerun. For example, instead of individual tributes, it could be family - based teams. This would force characters to protect their loved ones in the deadly arena.
Another plot idea could be that the tributes from the previous games who died somehow come back to life for the rerun. This could be due to some Capitol experiment gone wrong. It would be really interesting to see how the living tributes react to seeing their dead friends or foes again.
One idea could be to have the previous victors be forced to compete again. This would add a whole new level of drama as they already thought they were safe. They could also form alliances based on their past experiences in the games.
Change their backstories. Maybe a character who was from a wealthy district in the original now has fallen on hard times and is from a poorer district in the rerun. This would change their motivation and how they interact with others. They might be more desperate or more empathetic depending on the change.
One possible plot idea could be a new kind of alliance formed during the Mating Games. Contestants might team up not just for survival but also for the sake of love. For example, two tributes from different districts could fall in love and try to find a way to both survive and be together in the end.
One idea could be exploring the backstories of the minor characters in more depth. For example, the tributes from the districts that we don't see much of in the original books. Another could be a what - if scenario, like what if Katniss had a different mentor who was more ruthless or more kind - hearted. A third idea could be to focus on the post - Hunger Games lives of the victors, and how they deal with the trauma and the new - found fame or infamy in their districts.
Well, a plot might involve a new student who arrives at the school and uncovers a secret Hunger Games - like game that has been going on for years among the faculty. Or perhaps a group of students form an alliance to change the school's strict and unfair rules, much like the tributes in the Hunger Games form alliances. They could use their wits and skills to outmaneuver the school administration.
A great plot for Hunger Games Book 4 Fanfiction could be about a new character who discovers a hidden power within the ruins of the old arena. This power could be something that could either save or destroy the new - found peace in Panem. Or perhaps a story where the children of the main characters from the original trilogy face a new challenge that is related to the dark past of the Hunger Games, like a resurgence of the old Hunger Games ideals in a small, underground movement. Also, a plot about the Capitol trying to rewrite history and the fight of the districts to preserve the truth would be really interesting.
One idea could be that the college students are divided into different academic departments as districts. They have to compete in challenges related to their studies, like a science department having to solve complex equations under pressure. Another could be that the 'tributes' form alliances based on their dormitories.
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.
Perhaps the blight is a man - made weapon created by the Capitol to make the Hunger Games more 'exciting'. In the fanfiction, a group of tributes could team up to find a way to expose this and stop the Capitol from using such cruel tactics. They might face many challenges as the Capitol tries to keep their secret.
One plot idea could be exploring Madge's life before Katniss went to the Hunger Games. Maybe she had her own struggles or secrets in District 12. For example, she could be involved in an underground resistance movement that not many knew about.
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.