Editor's note: Don't miss the premiere of "The Bully Effect" on "AC360" at 10 p.m. ET Thursday, Feburary 28. And visit CNN.com Health on Wednesday, February 27, for our story on how technology has changed bullying.
(CNN) -- Eva was a bully. Tall for her age, she used her height to intimidate her peers. She made fun of those without designer clothes and got suspended several times for fighting.
She was also well-liked, outgoing, funny -- and a victim of bullying herself.
"When you're in junior high, you're just trying to figure out who you are," the 24-year-old remembers. She says she bullied others because she was, as were most kids, insecure.
As a parent, you probably have a picture in your head of the kid you'd vote Most Likely To Bully Others. He's burly, wears a letter (or leather) jacket and has been a senior longer than most students are in high school.
But experts say the bullies tormenting students nowadays aren't like the ones we see on the big screen. It's not just a small group of jocks, or the loner stoner pushing kids into lockers between periods. It can be almost anyone, at any time. And the most likely targets of bullies? The bullies themselves.
Sociologist Robert Faris calls it "social combat." He says the majority of bullying takes place in the middle of a school's social hierarchy, where students are jostling with each other for higher status.
Think of it like a giant game of king of the hill. Each kid is struggling to make it to the top, not afraid to step on others to get there. The closer you get to being king, the more vicious the competition gets between rivals.
"Bullying works," Faris says simply. "When kids pick on other kids, their status increases."
Faris teamed up with CNN's "AC360" in 2011 to study bullying at a high school in Long Island, New York. Researchers asked more than 700 students about their friendship circles and bullying behaviors. Faris has also completed similar studies in rural North Carolina -- where the demographics were different, but the results were the same.
Faris found 56% of students surveyed were involved in aggression, victimization or both at any given time. The main motive behind a student's bullying was to increase his or her popularity. The higher a student rose on the social ladder, the more likely they were to bully others -- and to be bullied themselves.
"There's always some tension in these friendship groups," Faris says. "Who's closer to whom and who's hanging out together, and I think that's what's driving a lot of these kids."
The same is true for middle-school students, according to UCLA psychology professor Jaana Juvonen, who's been studying bullying since the mid-1990s.
Juvonen and her team recently followed more than 1,800 students through seventh and eighth grade to determine how physical aggression and the spreading of rumors played a part in social prominence.
"What we've learned about bullying during the last decade or so is that it takes many forms," Juvonen says. "Some of these forms are extremely hard to detect. They're covert."
Administrators have cracked down on physical aggression in schools, enforcing zero tolerance policies for fighting between students. But Juvonen says that has led to subtler forms of bullying.
Rumors -- most often about a student's sexuality or insulting family members -- play a big role, according to Juvonen's research.
Faris recalls he got his "ass kicked" regularly as a child. Two brothers used hunt him down every day after school as he walked home from the bus stop.
But he says a daily beating was much less painful than the isolation he felt when his family moved across the country and he couldn't seem to fit in. "That was much harder to deal with than a bloody nose," he remembers.
In his later research, Faris found friends often exclude each other from gossip sessions or parties to put down a rival and boost their own status. Social media has also increased the prominence of this abstract form of bullying.
"The status competition is always there; there's no break from it," he says. "They go home and they get online and they see their friends doing things together and they're not invited, or worse, people are harassing them."
If the 2004 movie "Mean Girls" taught us anything, it's that girls are the queens of covert bullying; no one could make you feel as badly about the way you look as the popular clique. Juvonen's study, however, found boys and girls spread rumors to boost their social status -- and that both genders use physical aggression to assert power.
Eva knows this firsthand. She and her friends used to "jump" other girls, pulling their hair or punching them just because they talked to the wrong guy.
"I look back and shake my head," says Eva, who asked CNN not to use her last name because she plans to apply for graduate school. But "when you're in elementary school and junior high, there's nothing else. We don't have responsibilities. We don't have skills. We buy candy and do homework."
"Part of the problem here is that kids are kind of stuck in a cage," Faris agrees. "They don't have formal roles and responsibilities. ... They have to work status out for themselves."
And if we put adults in a similar situation, he says, we'd see the same behavior.
For that reason, Faris advocates programs and activities that de-emphasize social status and re-emphasize the qualities of a good friend. He hopes that one day students will leave high school with a small group of close friends, rather than the 300 or 400 they know on Facebook.
Juvonen says anti-bullying programs should focus on bystanders -- teaching kids that watching is just as bad as doing the bullying yourself. Studies in Canada have shown, she says, that if a child intervenes, the bullying incident stops within seconds.
Juvonen suggests parents use teachable moments on TV or in the news to show children right from wrong in a bullying situation. "They could be the ones pointing out to their kids that they have a lot of power as bystanders," she says.
Juvonen knows it's unreasonable to expect a child to be brave on his or her own; no one wants to become the next victim. So she suggests teaching kids about the weight of a group.
"Bullying involves this imbalance of power where the bully has the high status and is using this status," she says. "You can try to offset the power balance by telling kids to join one another as they try to intervene."
Parents also need to be aware of how easy it is for children to get sucked in to this social combat, Juvonen says. They can't be in denial about incidents that are brought to their attention.
"Anyone in that situation should be asking, 'What's going on?' 'What is it about these situations that brings about this kind of behavior?' " Parents should be having frequent conversations about what's happening at school, know who their children are hanging out with and keep an eye out for warning signs that something's not quite right, she says.
"The parent's role is really to be there as a buffer, be the one who listens."
Before she was a bully, Eva was a victim, she says. Older kids would call her names or hold her down to show they were stronger. She's the baby in the family, she says, and her parents didn't have time to pay attention to what was going on.
"(Bullying) comes from home, from family members," she says. "We hear our cousins and uncles talking crap about someone. We think it's funny. We think it's cool."
Eva never faced consequences for bullying, other than her suspensions. She believes that if someone had sat her down and told her that bullying was wrong, she would have listened. For years, she worried that one of her former victims would invite her on the "Maury Show" for a face-to-face showdown. She still feels badly about the pain she inflicted.
"I can't take it back," she says. "But if I could do it all over again, I wouldn't do what I did."
Did you ever bully anyone? Share your story in the comments below or on iReport.