The Show’s Not Over Until the Mockinjay Sings

Katniss, 5 seconds later:

Here are my clues:

She was Maysilee's friend. She got her canary after she died, inheriting the symbol of a warning in the form of a songbird.

Haymitch's victory frightened Show. If the Capitol's control was strong at the time, Haymitch's forcefield trick would have been just good tv. The fact that Snow came down so hard on Snow suggests there were threats of rebellion before Haymitch even went into the arena.

When Gale is whipped, Haymitch says they used to take people who got whipped to Katniss's mother. Specifically, he says, "She's the one we took them to," which seems to imply it was just her, not her whole family.

After treating Gale, she briefly speaks to Haymitch about "before." They understand each other so easily with just a few words despite us seeing hardly any interaction between them before. It feels like they have more of a shared history than what Katniss knows.

Speaking of what Katniss knows, she considers this interaction and wonders what they are talking about but decides she's too upset to ask right then. She never thinks about asking again, but the whole thing suggests that there is a lot more to the story of D12 in Haymitch and her parents' youth.

Katniss remembers her mom getting angry at her dad for teaching her "The Hanging Tree." Little Katniss had cried because her mom yelling was so out of the norm. Katniss assumes that her mom didn't like her little girl learning such a dark song, but we know better. Her dad sang a rebels' song, and her mom got scared of him teaching it to her daughter.