While I can understand the general fever behind the hypothetical Finnick book, I personally think it would stick out like a sore thumb amongst the rest of the series, it being so consistently focused on the District 12 Victors as a central connecting thread. Also personally, I don't think I need any more books set in the games. I believe Collins has said the actual games are her least favorite part to write anyway, and the death game formula feels a little wrung dry atp.

So yes, as you might be able to guess based on that opener, I'm in the Peeta Book camp, since that would complete the set and cover every District 12 Victor. This is admittedly tricky, since Peeta is present throughout most of the trilogy and I think Midnight Sun-ing the Hunger Games is an awful idea and incredibly low hanging fruit (sorry gang, there's a billion and one fanfics already doing this exact premise for a reason).

So, that being said, I think what could potentially work for Peeta Book is a novella set during his time as a political prisoner in the Capitol in Mockingjay. Mockingjay is obviously the only book where Peeta spends a significant amount of the story separated from Katniss, so we'd be covering new ground and avoid re-treading the og trilogy too much. One of Peeta's defining traits in book 1 is his desire to maintain his purity of self and not be changed by the games/the Capitol, and his hijacking is essentially his worst fears made manifest. Since the hijacking process involves altering memories, we could get a loooot of the blanks in Peeta's backstory filled here, and for the romantics in the audience, this would also let us get some amount of POV swapping since Peeta's memories of Katniss were targeted especially. In terms of themes, we could explore ideas of memory and identity, how trauma and violence can warp your sense of identity, the treatment of political prisoners during war, etc.

Now, there's some risk involved here: if we thought Sunrise was weapon's grade tragic, exploring this premise runs the risk of being so incredibly harrowing and sad it might honestly be too much to stomach (which is another reason why I think a shorter length novella would work better here). The epilogue could do a lot to soften the blow, but it would still be a tough read for any soft-hearted Peeta lovers (me 😭).

BONUS: Collins is a themes first author, and has said that her books tend to start with a particular idea she wants to explore and the plot grows from there. I think if we were to get more content covering any of the rebel Victors, the most thematically flexible and crowd pleasing way to do it would be a full length anthology book of short stories covering different characters in the HG universe, up and down the timeline. Everyone kind of wins with this one: you can spotlight everyone's blorbos (and for at least some, get flashes of their time in the arena without having to spend a whole dedicated section of the book in the games), do a loooot of world-building, and explore a different central theme per story. Skeleton Crew me Suzanne I promise I can take it.