In the four short but memorable seasons of The O.C. that fans have to enjoy, we also really get to watch the core four grow. But perhaps the biggest transformation comes from the most unexpected heroine: Summer Roberts. Originally just seen as a shallow, self-centered valley girl, she blossoms into a boho princess who cares... most of the time. Summer Robert's growth over those four years shows she could be deep, multilayered, and maybe even capable of saving the world.
What's particularly interesting with the ways Summer changes over the course of The O.C. is how Summer also doesn't change. That is to say, throughout the series she manages to become a better, more fully-rounded person while keeping true to herself. Hell, she's unfaltering about using her love of Miuccia Prada to get into Brown ("Her clothes teach you to change your perspective"). You do have to love that she wants to achieve and evolve on her own merits, not on the stock answers that people would expect of her. Classic Summer, through and through, and she's an inspiration because of it.
However, if you want more concrete examples of what exactly happens to Summer Roberts between the pilot and the finale, scroll down.