Katniss is the main character in Catching Fire because the story is from her point of view. She is also the main character from the first book of The Hunger Games series, making her the main character of the whole series.
Other reasons why Katniss is the main character include:
The main character
Yes
The protagonist is Katniss Everdeen. She is the first-person story teller and the main character of the series.
Yes. Catching Fire is written from the narrative perspective of the main character, Katniss.
Katniss does not find out in Catching fire, but in the first book, when they are in the cave by the river.
No.
no they do not
Peeta
No, but she does in Mockingjay.
Katniss does what Haymitch does
Still Katniss Everdeen.
Yes he does. In Catching Fire Gale reveals that he loves Katniss.