Katniss laughed again, a freer sound than she'd made in a long time. It was just such a ridiculous idea, that she'd be the seductress between the two of them. Not because he was so flirtatious, but because she was so terribly bad at it. "You got me,' she said. "That's exactly what I'm trying to do."
She was relieved twice over, because this was something they could joke about, and because if he could be so humorous then he must be feeling better. Or at least, pretending the reason she was here was to seduce him and sleep in his bed would help him shake off the nightmare.
More seriously, she added, "If you want me to stay, I will."