It's more like what I did, Katniss thinks before she can stop herself, and why should she? Despite everyone's words telling her otherwise, she knew that the firebombing of 12 was her fault. A direct reaction to her firing that one arrow. While events might have been leading up to it beforehand, it would be stupid not to include her own actions as being the cause. The problem was that nobody else understood.

It's her turn to scrutinize him, wondering if he's ready to hear the news that their only home was gone. Yet she had told him far worse in the past few days, which was both encouragement and something that made her second-guess her decision to have this talk now.

"It's about the future. But it wasn't your fault. Actually, you... you were the one who helped the most."