When the story starts out, Adina is so not a team player. That's because unlike the other teen beauty queens who crash-land on the island, Adina isn't looking to win. She's so anti-pageant-culture that she wants to turn the pageant into a joke by writing an exposé. But, as we've pointed out a few times now, no beauty queen leaves the island with the same goals as when they came in.
Adina's lucky that Mary Lou is first to find her on the sand. In the beginning of their friendship, Mary Lou makes all the friend moves: she refers to Adina as a friend by Chapter One and offers to help her fish (despite the fact that she's a vegetarian) in Chapter Eleven. It's only when she calls Adina her best friend in Chapter Nineteen that Adina starts to pay attention. Some people really don't get how friendship works.
On her side of the equation, Adina is blunt with Mary Lou (as per her personality) and isn't afraid to give her a hard time about things she doesn't agree with, like Mary Lou's purity ring. But if anything upsets Mary Lou, Adina is totally in her camp.
Almost as quickly as she makes a friend, Adina makes an enemy. First, she challenges Taylor, running against her for the role of Team Captain (which she loses), and then generally acts as the negative foil to Taylor's dogged positivity.
We're definitely meant to side with Adina—Taylor's such a caricature that readers, as outsiders to the pageant world, are meant to see her character through fellow outsider Adina's eyes. Especially when Adina does things like tell the other girls that they should focus on survival, not pageant practice. Sounds like a logical plan to us.
But even though Taylor is a little much, she sees through Adina's tough veneer, and she's right to point it out:
"Your problem is not having any trust. You expect the world to fail you, so it does. And then you get all pouty-pants about it." (9.57)
Adina must know on some level that Taylor is right, because after hearing this, she does start to open up and even become slightly hopeful. She accepts Taylor's challenge of eating the first grub, and goes on to take the other girls' ideas seriously. She even allows herself to like a boy.
When Taylor goes crazy, Adina's the one to try and coax her back to the group, and later she's the one who asks Taylor for her help. Taylor saw something about Adina that she was trying to hide, so our later-in-the-book, more open Adina tries to return the favor.
Adina's a feminist, and kind of a man-hater, but the latter isn't because of her feminism. It's because of her mother, who, we learn early in the novel, had "gone from one guy to the next, in an act of downward husband mobility, until she'd married Alan the Tool." (5.3) Adina wants to be as different from her mother as possible, so when cute sort-of pirates are shipwrecked on the island, she tries to avoid them. At least, at first.
But Duff, a.k.a. Jerk, likes a challenge, so he goes after Adina. At first, she hates herself for being attracted to him, but then actually enjoys herself and feels good when they have sex.
When she finds out Duff made a tape of it, her initial thought is that she's the same as her mother. Sad sauce. But after going against The Corporation with her fellow beauty queens, she realizes that the difference between her and her mom is that she doesn't need a boy to fill a hole in her self-esteem.
In the end, Adina becomes the kind of leader who listens to other people's ideas, who doesn't look down on the others. She holds onto her feminism, but doesn't feel it's degrading to strut and snap down the runway in the final chapter. Empowerment is what feminism is really about, after all.