When we meet Haymitch Abernathy early in The Hunger Games, he is stumbling drunkenly onstage to mentor Katniss and Peeta, convinced he is about to watch them both die despite his best efforts to prevent that outcome. Throughout the original trilogy, we meet many victors who have developed substance abuse problems while trying to cope with their Games-related trauma; Haymitch is not unique in this. Essentially, Sunrise on the Reaping shows us specifically why Haymitch became a drunk—and why he became a rebel.
