REGINA: It was my parents' room, but I made them trade me.
We don't even want to know how Regina managed to bully her parents into giving up the master suite.
REGINA: I mean, I don't care; do whatever you want, but let me just tell you something about Aaron: all he cares about is school and his mom and his friends.
CADY: Is that bad?
It's bad if you're Regina and it means that Aaron doesn't put you before everything and everyone else in his life, which means that your powers don't fully work on him.
GRETCHEN: If you even knew how mean she really is. You know that I'm not allowed to wear hoop earrings, right? Yeah. Two years ago, she told me that hoop earrings were her thing, and that I wasn't allowed to wear them anymore. And then for Hanukkah, my parents got me this pair of really expensive white-gold hoops. And I had to pretend like I didn't even like them, and it was so sad.
The fact that Gretchen would go to these extremes to please Regina illustrates the crazy-tight hold that Regina has over her minions—and that she's a terrible, terrible friend.
KAREN: You wanna do something fun? You wanna go to Taco Bell?
REGINA: I can't go to Taco Bell. I'm on an all-carb diet. God, Karen. You are so stupid!
GRETCHEN: Regina, wait. Talk to me.
Regina runs out of the room. Gretchen follows her.
REGINA: Nobody understands me.
GRETCHEN: I understand you.
This exchange, where Gretchen literally follows Regina out of the room, does a tidy job of summing up their relationship. Gretchen will follow Regina to the ends of the earth to get her approval.
CADY (V-O): I had learned to control everyone around me.
She taps Aaron on the shoulder.
CADY: Hey. I'm having a small get-together at my house tomorrow night.
AARON: Is Regina going?
CADY: No. Do you think I'm an idiot? No, it's just gonna be a few cool people, and you better be one of them, biotch.
AARON: Fine, I'll go.
CADY: Shut up. I love that shirt on you.
Yeesh. Cady's turned into a clone of Regina at this point, not just because she's using obnoxious expressions like "biotch" and "shut up," but because, by her own admission, she's learned to control everyone around her.
REGINA: She think she's gonna have a party and not invite me? Who does she think she is?
SHANE: You're right, hon.
REGINA: I, like, invented her, you know what I mean?
This is as close as we get to Regina admitting the extent of her power—and her intent to manipulate people—in the movie. She thinks she deserves for Cady's personality, popularity, everything. She's like North Shore's Dr. Frankenstein but with more expensive shoes.
DUVALL: Now what the young ladies in this grade need is an attitude makeover, and you're gonna get it right now. I don't care how long it takes. I will keep you here all night.
JOAN THE SECRETARY: We can't keep them past 4:00.
DUVALL: I will keep you here until 4:00.
The faculty at North Shore—Mr. Duvall, in particular—don't hold nearly as much as power as the students do in Mean Girls.
CADY: I'm sorry.
NORBURY: I forgive you, but as my own personal form of punishment, I figured out how you're gonna earn that extra credit.
Ms. Norbury uses her power both as a teacher and as a person for whom Cady has respect in order to get what she wants: a Mathletes State Championship.
CADY'S MOM: Where's Cady?
CADY'S DAD: She went out.
CADY'S MOM: She's grounded.
CADY'S DAD: Are they not allowed out when they're grounded?
It's not just the North Shore faculty who are powerless in Mean Girls; the parents are all ineffective, too. Well, maybe not Gretchen's dad, the inventor of toaster strudel, but we don't ever meet him.
CADY (V-O) Miss Caroline Krafft seriously needed to pluck her eyebrows. Her outfit looked like it was picked out by a blind Sunday school teacher, and she had some 99-cent lip gloss on her snaggletooth. And that's when I realized, making fun of Caroline Krafft wouldn't stop her from beating me in this contest…Calling somebody else fat won't make you any skinnier. Calling someone stupid doesn't make you any smarter. And ruining Regina George's life definitely didn't make me any happier. All you can do in life is try to solve the problem in front of you.
Looks like our girl Cady's having an epiphany here: Manipulating, and just generally being a jerk to, other people doesn't give you power. It just makes you a manipulative jerk.