Who controls katniss? How do they show this? How does katniss go against them?

Really nobody controls Katniss, that is what makes her such a strong female character. The Game makers and President Snow think they can control her. They change the rules of the competition as it is being played out. Katniss, however, knows how to defy these people on camera. She threatens to pull a Romeo and Juliet with Peeta and the poisonous berries. They back down.

What does pull a Romeo and Juliet mean Asian

Oh, they threaten to kill themselves with those poison berries at the end.