I think a character who has a split personality could be really interesting. One side of them is meek and scared, but the other side is a fierce fighter. During the bloodbath, the switch between these two personalities could create some really intense moments.
One idea could be focusing on a new tribute who has a unique survival skill, like being able to communicate with animals. They use this skill to their advantage during the bloodbath, getting early warnings about approaching threats. Another could be a group of tributes forming an unexpected alliance just before the bloodbath to take on the stronger tributes together.
Often, the baby tributes with the most unique abilities are the most interesting. For instance, a baby who can communicate with animals in this fanfiction world stands out. Their ability could give them an edge in the 'games' and also make for some really cool storylines.
A girl from District 11 who is an expert at climbing trees could be a great main character. She could use her skills to hide from other tributes and also find food sources in the arena.
A previous victor forced to return to the Games for the 50th edition could be a great main character. Their experience from the past would give them an edge, but also a lot of emotional baggage. It would be interesting to see how they handle the new challenges and younger opponents.
It could be a young girl from District 4. Her district is known for fishing, so she has great swimming and underwater skills. In the 71st Hunger Games, she could use these skills to explore parts of the arena that others can't reach, like underwater caves where she might find valuable resources or a secret passage. Her character arc could be about using her district - based skills to overcome the challenges of the games and perhaps even question the whole system of the Hunger Games.
A young girl from District 12 who has been secretly training in combat skills her whole life. She could be the main character, using her wits and skills to survive the games.
Katniss is always interesting. You can explore her thoughts and feelings more deeply, like her internal struggles during the Games. Peeta is also great. You could write about his life after the Games, how he deals with the trauma. And then there's Finnick, his charm and his secrets make for great fanfiction material.
Definitely Katniss. Imagine her in an arena filled with Halloween - themed traps and challenges. She would be the one to cut through the spooky nonsense and focus on survival. Gale could also be a great addition. His hunting skills would be put to the test in a different way, like hunting down muttations that are disguised as Halloween creatures. Then there's Cinna. He could design some amazing Halloween - inspired outfits for Katniss that not only look great but also have some hidden functions. For example, a dress that can turn invisible in the dark like a ghost. Finnick could also be interesting, with his charm and his ability to adapt to the strange new Halloween - themed Hunger Games environment.
Perhaps an older brother who volunteers to take his younger sister's place in the 50th Hunger Games. He has a strong sense of family loyalty and his journey in the Games could be about protecting the other tributes who remind him of his sister.
The main character could be a young engineer who works at the dam in District 5. He or she has a deep understanding of how the dam operates and is determined to use that knowledge to better the situation in the district.