Symbolism, Imagery, Allegory
Deanna's Hair
We'll say it straight out: whenever Tommy wants Deanna to go down on him, he pulls on her ponytail. Charming, right? Deanna tells us, "I remember exactly how it felt when he wrapped my ponytail around his hand, pulling it back until I got the hint that he wanted me to go down." (3.96).
So when she gets to work her first night at Picasso's with her hair in a ponytail and sees Tommy, she quickly tucks it into a bun. Tommy's noticed, though—he says, "Where's your ponytail, Dee Dee?" (3.99). Deanna's ponytail represents her loss of power; when Tommy sees it and comments on it after three years, it's like she's right back in the Buick with him, being made to do something she doesn't want to do. She can tuck it into a bun just like she can slink down the halls of Terra Nova, but Tommy and his friends will still see her as a "slut."
Stacy's Hair
Stacy has this thing she does, this move. No matter what's going on, she can pull herself together by giving her head a shake and putting her right hand on her hip in this certain way, and it's, like, holy crap, don't mess with that girl. […] I saw her do that move after Darren's ex, Becky, shoved her down a couple of stairs at the Taco Bell at the beach. (2.122)
So says Deanna about the former toughest girl in school, who's now raising a baby in Deanna's basement. It's a symbol of power, a sign that Stacy doesn't let anyone mess with her or her man. Nothing fazes her, and because everything fazes Deanna, she thinks it would be helpful to have a move like that.
It's really sad, then, when Stacy dyes her hair with a forgotten box of Copper Sunset dye that Deanna finds among Stacy's stuff in the basement. She's gone from Bad Girl to Teen Mom, and she's hoping the change of hair color will put a little spark back into her relationship with Darren.
But when he comes in and sees it and just says, "I've always wanted to kiss a hot redhead" (6.36), Stacy's so disappointed that she runs off with her old pal Corvette Kim for a few days. Dyeing her formerly powerful hair red and having Darren laugh it off is sort of the opposite-gender, Pacifica version of Samson losing his locks to Delilah.
Hair represents both female power (or loss thereof) and female sexuality in Story of a Girl. It has the power to attract guys—Tommy gets turned on pulling on Deanna's ponytail, and Darren by the idea of kissing a hot redhead—but it's also a way in which guys can take away their power. Both Tommy and Darren's responses to girls' hair are degrading, even if Darren's just clueless and not doing it intentionally.