CHARACTERS HISTORY (taken from Wikipedia):

Finnick Odair:
Finnick is 24 years old and described as being very handsome and tall with tan skin, bronze hair, and stunning sea-green eyes, making him very popular with people in the Capitol. He is known for having many lovers in the Capitol, none of whom he stays with for long. At age 14, he won his first Hunger Games by using a trident and a net against other tributes; District 4's trade is fishing. Katniss remarks that a trident given to him by a sponsor may have been the most expensive gift ever seen in the games. During the Quarter Quell, Katniss is hesitant to make Finnick her ally, because she does not trust him—he seems to her to be shallow, arrogant, and superficial—and does not want to become close to him and then have to kill him, but he proves to be a valuable and trustworthy ally, saving Peeta using CPR and using his district skills to provide shelter. When jabberjays that make sounds of the screams of loved ones being tortured appear in the Quell, the one made to target Finnick uses the voice of Annie Cresta, his "poor, mad" lover back home, who won her own Games a few years before, but went insane after seeing her district partner decapitated. In Mockingjay, Finnick enters a deep depression as a result of Annie's being held prisoner in the Capitol. He helps the rebellion by appearing in rebel propos and revealing the fact that victors are routinely prostituted to wealthy citizens of the Capitol by President Snow, which is why he was seen as having a string of lovers. He then reveals all of the political secrets he learned from clients, including that President Snow owes his position to having poisoned his opponents. He is reunited with Annie (when District 13 retrieves her, Johanna, and Peeta from the Capitol), and they get married. Finnick is a member of the "Star Squad" that goes to fight in the Capitol during the final stages of the rebellion. He is decapitated by lizard muttations during the attempt to infiltrate the Capitol. Some months after his death, Annie has their son. Finnick is characterized as being personable and down-to earth, with a quirky sense of humor. After an initial period of distrust, he and Katniss become good friends.

Cato:
Katniss considers Cato to be her and Peeta's most fearsome opponent because of his size and strength, skill with many weapons, and savage pleasure in killing. Like most Careers, Cato has complete confidence in his abilities and expects that he will be the victor. Katniss believes he is not completely sane after seeing his reaction to the destroyed food supply. He is the last tribute to die. During the finale of the Games, he is pushed off the Cornucopia to the wolf muttations—fearsome creatures created in the Capitol—who prolong his death to the point that, when Katniss finally shoots him to put him out of his misery, he is nothing more than a gnawed and bloody hunk of meat. In the film, he holds Peeta in a death grip and pleads with Katniss to shoot him, having become disillusioned with the games and the Capitol, and finally realizing that their deaths were meant to be nothing more than entertainment.