He's gone from mixtapes to mainstream. But who exactly is this Philly cat that the streets respect and the ladies adore? Swizz Beatz' protégé Cassidy opens up on his journey to the top of the charts.

They say anything can happen in Brooklyn. But when you're at the infamous Canarsie nightclub The Rock at 3:30 a.m. on a bone-chilling February Thursday, the axiom takes on an ominous tone. A scuffle breaks out when a group of impatient hardrocks tries to bum-rush their way inside. A steady stream of barely legal girls in painted-on jeans and thigh-high skirts make their way into the dancehall--more Caribbean-style gymnasium than mirror-ball disco. The smell of long-soaked-in liquor rises from the club's worn carpet and dank marijuana smoke permeates the air as a small team of bouncers stakes out the pensive crowd.

"This is Brooklyn," proclaims promoter Walter "Hit Man" Porter, who is overseeing the club's early-morning entertainment. "You know you are going to get the thugs. But as you can see, a lot of girls are here. They came out for Cassidy."

On a beige leather sofa in the corner of a crowded VIP room, a young MC from North Philadelphia is preparing for his BK debut. Wearing a button-down Coogi shirt and baggy blue jeans, five-foot-six and babyfaced, Barry "Cassidy" Reese could easily be mistaken for a high-schooler out past curfew. The highly touted 21-year-old looks serious, though, intense. While his debut single "Hotel"--a hip-hop ode to late-night creeping recorded with R&B love bandit R. Kelly--is currently no. 8 on Billboard's Hot 100, the fastest-rising radio hit on the charts, Cassidy knows those sorts of stats aren't enough to earn the respect of a notoriously hard-to-please Brooklyn crowd.  

"Different crowds like different things," Cassidy says, minutes before he's set to go on. "This is a reggae type of a crowd, and it's also a late-night grimy type of crowd. So you know you gotta come a little bit harder than usual. When you go out to a club and you in the hood, anything can jump off. But I fuck with these types of crowds."

Taking the stage with the standard hip-hop entourage of hype men, bodyguards and various crew members, Cassidy wastes no time in acknowledging his audience's rep. "There's a lot of fake niggas that are scared to come to Brooklyn," he says, peering out from under the lights. "Because they know how you niggas get down!" A couple of voices from the crowd immediately shout out in agreement. "Don't let this 'Hotel' shit get you fucked up! I'm from the hood!" More cheers. Approval. The Philly kid gets a pass.

Cassidy was destined to become an MC. Looking out into the myriad faces at The Rock, though, it's uncertain if the crowd is familiar with him aside from the infectious commercialism of "Hotel." Are the screaming girls in the front row aware that this is an MC who was crowned battle-rhyme champ on Philadelphia's 103.9 The Beat at the Similac age of 15--after thoroughly thrashing a string of contenders nearly twice his age?

Do they know that by age 18, the confident lyricist was handpicked by former Ruff Ryders

  in-house producer Swizz Beatz to anchor his Full Surface Records--a company distributed by industry titan Clive Davis's powerhouse, J Records? Has anyone out there witnessed the now-legendary underground video footage of Cassidy besting Roc-A-Fella capo Freeway in a face-to-face, mano-a-mano competition?

Born and raised in turbulent North Philly, Cassidy's first introduction to hip-hop came from an unlikely source. His parents, both rap fanatics, would play the likes of early Eric B. & Rakim and Jazzy Jeff & the Fresh Prince around the house. "My parents came up in the hip-hop generation," he says. "My dad was into the music before I was even born. He had a single out that made the local radio in Philly. I was born into it."

By his early teens, the kid who came up on a steady diet of Big Daddy Kane, Kool G Rap and Scarface was earning his battle stripes at Philly's historic Broad and Olney train station, destroying older combatants with a lyrical depth that was beyond his years. When Cassidy called in to the hip-hop radio program The Cipher, the adolescent lyricist, then known as The Boy B, dominated the show's battle-rhyme segment for weeks, gaining celebrity status in the hood. Cassidy even made a believer out of a much-heralded fellow Philly spitter who had recently signed to Jay-Z's Roc-A-Fella Records.

"I was rhyming in a Philly studio where Beanie was at," says Cassidy of his first encounter with the notorious Mack from Sigel Street. "I started rhyming and he was like, 'Hold up, dawg. What's your name again? Is it The Boy B from The Cipher?' And I'm like, 'Yeah.' And Beanie is like, 'Oh, shit! Wait 'til I call my niggas and tell them I was in the studio with The Boy B!' Beanie was on at the time, and I'm thinking I'm supposed to be going crazy for him like that!"

Brooklyn is just one of the many promotional stops Cassidy is making in support of his debut album, Split Personality. Hours before his gig at The Rock, Cassidy was at Midtown Manhattan radio station WBLS for a scheduled interview with controversy-courting afternoon jock, Wendy Williams. His manager, a stout, serious-minded 43-year-old named Terrence Dean (Swizz Beatz' father, and brother of Ruff Ryders Records owners Dee and Wah Dean), was on the phone gathering information about the upcoming schedule of drops and freestyles to be recorded for a fleet of radio shows around the country. It seems "Hotel" has made Cassidy a wanted man. When the question arises as to whether such an easy-listening hit might damage his credibility, Cassidy dismisses the idea.

"The people that only know me from 'Hotel,' that don't know about the battle raps or my mixtape stuff, are not really into that anyway," he contends. "Biggie would go with something like 'Hypnotize,' and then still do a 'Ten Crack Commandments.' It's not like I had a cat standing over me changing my style, or changing the way I dress. A commercial song like 'Hotel' is also me. And when the street level comes together with the mainstream level, that's when you got a movement."

Swizz Beatz is more adamant in defending his protégé's commercial success. "I never feel like we are selling out," says the CEO defiantly. "Because at any given time, 300 bars-plus is on hand for anybody that's a nonbeliever. Cassidy has a talent to cater to people, and also the ability to shut down the streets."