Serena is a wealthy girl who seems to have everything she could possibly want. To others, she appears confident and as if things come easily to her. She sees herself as a failure and really wants to prove that she can be taken seriously. This is why the Film festival is important to her. If she wins, she will show others that she has talent and can do something on her own.
Serena is kind to others even when they are cruel to her. This is shown in the way she shows concern for Blair even when Blair shuns her. She isn't self-serving. When she wins the prize for the film festival, she makes certain that everyone knows she didn't do it on her own, and she gives away her prize. Serena is mild but resilient. She knows she didn't do well in her college interview, but she regroups and finishes the interview with class.