Why is Katniss personality so hard ?

Her personality is so hard most of the times but, then so soft. Better yet, in her entrance at the capital she played a inicent girly girl. Including her interview. Haymitch was well suprised from where this charecter came about. Deep down Katniss plays different roles, maybe within her favor. Another great reason to envy her and, love her for her great personality. Is she hard because of the situation the government puts her in. That may be an option. We may reconsider who is truly Katniss? At times we adore her for who she is and, at times we dont. Katniss may just be running in a mix of emotion and just trying to figure out who she herself really is and, what exactly she needs to accomplish so far if she hasen´t done so. Maybe, that why she plays different roles? Either way Katniss will reason to understand what personality you play and, why?