In conversations with Justin, other minors with for-pay sites admitted to being scared of certain fans. Some adults wrote things like "It wants to possess you." They had special wardrobe requests for the adolescents: in jeans with a belt, without a belt, with a lacy bra, showing legs, showing feet, wearing boxers with an erection, and others.

One 16-year-old who called himself hot boyy 23 finally found the entreaties too much. "Hey guys," he wrote when he shut down his site, "I'm sorry, there are just too many freaks out there for me. I need to live a more normal life, too. I might be back someday and I might not. I'm sorry I had to ruin all the fun."

It was not only the minors operating Webcam sites for pay who faced frightening adults. Earlier this year, a teenage girl in Alabama posed seminude on her Webcam in a sexually charged conversation with someone she thought was another teenage girl. But her new confidant, it turned out, was an adult named Julio Bardales from Napa, Calif., law enforcement officials said. And when the girl stopped complying, she received an e-mail message from Mr. Bardales containing a montage of her images. Across them was a threat in red letters that the images would be revealed unless she showed a frontal nude shot over the Webcam. Mr. Bardales was subsequently arrested. The police said he possessed images of more under-age girls on Webcams, including other montages with the same threat.

Justin says that he did not fully understand the dangers his fans posed, and before he turned 14, he was first lured from the relative safety of his home. A man he met online hosted Justin's Web site from Ann Arbor, Mich., and invited him there to attend a computer camp. Justin's mother allowed him to go, thinking the camp sounded worthwhile.

Another time, the man enticed Justin to Michigan by promising to arrange for him to have sex with a girl. Both times, Justin said, the man molested him. Transcripts of their subsequent conversations online support the accusations, and a video viewed by The Times shows that the man, who appears for a short time in the recording, also taped pornography of Justin.

From then on, Justin's personality took on a harder edge, evident in the numerous instant messages he made available to The Times. He became an aggressive negotiator of prices for his performances. Emboldened by a growing contempt for his audience, he would sometimes leave their questions unanswered for hours, just to prove to himself that they would wait for him.

"These people had no lives," Justin said. "They would never get mad."

Unnerved by menacing messages from a fan of his first site, Justin opened a new one called jfwy.com, an online acronym that loosely translates into "just messing with you." This time, following an idea suggested by one of his fans, he charged subscribers $45 a month. In addition, he could command large individual payments for private shows, sometimes $300 for an hourlong performance.