The best characters in stories are the ones who grow and develop throughout the story. The characters who are a little different at the end of the story than they were when we first met them.
Cordelia Chase, Wesley Wyndham-Price, Anne Shirley, Kvothe, Harry Potter and crew, Emma Wodehouse (and by extension, Cher Horowitz), Egwene Al'vere, Matrim Cauthon. I'm sure you have your favorites to add to this list.
I've been thinking lately about things I wish I could tell my junior high/early high school self. To be more comfortable in my own skin. To appreciate my true friends more, and to not spend so much time trying to catch the attention of "popular" kids. To be kinder to boys when things got weird, and to not put up with the mean girl behavior of one so-called best friend.
But hopefully, I look a little different these days than that pretty typical adolescent girl. I'm working on a nice character arc, and hopefully it makes me a more interesting person. And instead of bemoaning things I can't change, I can share what I've learned. I can put my arm around the 8th grade girl struggling with a friendship that is diverging and say -- "you know what. It's okay. Be kind, be yourself, and be open to new friendships. It's okay to be a little weird, because there's someone else as weird as you who needs buddy too."
So maybe I was a Gretchen with my own Regina George (who wasn't anywhere near that level, but that's another story). I can say with confidence that phase is long gone. And the journey isn't over. And I figure as long as my character keeps growing, it'll be a pretty interesting story. I'll be in good company at any rate.