Katniss and Peeta have an interesting history, unknown to anyone but them, as they begin their journey to compete in the Hunger Games.  When Katniss was about eleven, she and her family nearly starved to death.  This occurred shortly after her father had died and her mother had lapsed into a near catatonic depression.  Knowing her situation, but not really knowing Katniss, Peeta had purposely burned some bread in is parents' bakery so that he could give it to Katniss.  As the Games commence, Peeta announces that he has been in love with Katniss since they were young, and Katniss assumes that he has made that statement to create favor among the viewers.  So she is not particularly surprised when he allies himself with the rich Careers group of tributes who set out to hunt Katniss immediately; she assumes that is part of his strategy, to kill her, and that the statement about being in love with her was not true.  Of course, as it turns out, Peeta was using his alliance to steer the Careers away from Katniss as long as possible.  When the games are coming close to an end, Katniss pretends to be in love with Peeta, as she believes he is pretending to be in love with her, as they manage to manipulate their way to a double victory.  This victory will not be without a price, however, as President Snow will not soon forget being outsmarted by his victims on live television.