Sydney I think it's because the ending of Mockingjay was a little rushed to me, like the author had a deadline to meet and just wanted to get something on paper. Katniss's actions were out of character. As for Catching Fire, I guess people found the idea of a Hunger Games with old victors interesting.
Penelope S Kernen
This answer contains spoilers… (view spoiler)[The hunger games is narrated by a girl named katniss everdeen who lives in a world of sadness. 75 years ago North America was destroyed and a capitol known as panem rose up and made 13 districts with a theme for all the districts was made. The districts fought the capitol and lost the 13th district was destroyed and the others were defated and was punished by choosing a boy or girl 12-18 of age to fight to the death in an arena. In the first book Katnisses sister prim is chosen to be in the hunger games but katniss volunteers and the boy known as pests is chosen. Katniss was giving food by peeta when her family was dying. katniss is put into the arena and everyone dies except for peeta and katniss. They refuse to kill each other and almost commit suicide. They both make it out. The second book catching fire takes place 6 months after the hunger games. The president of panem is angry at katniss. Katniss and peeta lied about committing subside. Everybody thinks that they almost committed subside because of love but most people think they did it for defiance. A rebellion was forged and is growing. Her best friend Gale which she truly loved is thranted to be executed. President snow announced the quarter quell where the previous winners from the districts must fight again. Katniss is put into the game and at the end destroys the arena with not 2 but more survivors. Katniss wakes up and is told that her district has been destroys and district 13 is still active underground. Mockingjay takes place some time after catching fire and katniss has been living with her family. The president of district 13 president coin is telling katniss to do certain events to make another reunion. In return to save pests from the capitol. She does and is nearly killed. Pests and some others are saved but has been brainwashed and has been told to kill katniss. Katniss heads for the capitol and her sister prim is killed during the battle. They win the war and Katniss is about to execute snow but finds out that coin planned prim to die so she kills her instead. She is arrested and snow chokes on his own blood and dies. Katniss decides by voting to make another hunger games just for capitol children. Katniss and peeta have 2 children and live happily eve after. (hide spoiler)]