The Ballad of Songbirds and Snakes by Suzanne Collins
The Hunger Games story continues in this prequel that focuses on a young Cornelius Snow and his debut role as a mentor during the games. This is the antagonist's story, and it takes place in the years after the war between Panem and the rebels. The Hunger Games are still forming into what they will become, and Snow is an 18 year old learning what he is willing to do to gain power.
Review from School Library Journal:
Coriolanus Snow still lives in his once-great family's Capitol penthouse, but now he repurposes old shirts and eats boiled cabbage to quell his hunger pangs. He keeps up appearances among his fellow students and the faculty at the prestigious Academy, and remembers the war that ravaged the country, including the Capitol, 10 years earlier. During the reaping for the 10th Hunger Games, he's selected to mentor Lucy Gray Baird, a talented singer from District 12, and their success will determine whether he receives a much-needed scholarship to the University. This prequel takes place 64 years before The Hunger Games and follows the boy who will become cruel President Snow. Like the first book, this novel provides thrilling action and chilling gore, but the pace lags at times with school minutiae. The romance between Coriolanus and Lucy Gray feels forced, and much of the narrative functions mainly as world-building for the original trilogy. Fans will appreciate revisiting the world of Panem, and teens may relate to Coriolanus beginning to grapple with big ideas like human nature and whether people on opposite sides of a war are fundamentally different. Sejanus, a new money classmate from the districts, provides balance as he recognizes the Games as monstrous from the start.