Four lions greeted shoppers walking through Pentagon City mall in Virginia this spring. Their wild manes and toothy jaws were emblazoned on the front of T-shirts at the entrance to a pop-up shop for Spergo, a luxury streetwear line that emphasizes bold colors, soft cotton fabrics and a tapered, tailored fit.

"You see this stitching? Everything is embroidered," noted store manager Malik Goins, as he ran his fingers over an $80 Leo sweatshirt in canary yellow. Just past the Jefe swim trunks hung a display of Rodney joggers and hoodies with matching white piping details. A wall of caps, socks and masks overlooked the register counter, alongside a jumbo photo of Spergo CEO Trey Brown, sitting poolside with a smile. Nodding to the image of his boss, Goins said, "It's incredible to see what a 12-year-old did in three years."

What's maybe even more impressive is what Brown, a high school sophomore from Philadelphia, does every single day. His list of morning affirmations goes something like this: "I'm powerful. I'm strong. I'm a leader. I'm a billionaire."

Although that last bit isn't true — yet — it's a peek inside the mind responsible for T-shirts that have caught the attention of rappers and athletes, as well as plenty of folks in the Washington area. Or as Brown puts it, "We checked our analytics and the DMV really supported Spergo heavy."

Thanks to the success of the pop-up, Spergo opened a permanent Pentagon City mall location last month, just across from Cole Haan and Hugo Boss. Shopper Troy Ball, 34, recently left with a gray T-shirt, matching socks and plans to return. "When you see a lion, it evokes strength and passion," said Ball, who had come by to check out a new Black-owned business after hearing about it from a friend. "The logo speaks volumes."

Spergo's profile keeps on growing, along with Brown's to-do list. Just before his appearance on "Shark Tank" this month, he oversaw the move of his brand's flagship from Philly to a spot outside the city in the King of Prussia mall. He's also staying on top of his designing responsibilities because, as Brown explains, "fashion is always moving. There's winter, next spring, the winter after that." And of course, the 15-year-old is also juggling his schoolwork, which he's been doing online since 2019.

"I've just always had an older spirit," says Brown, whose first entrepreneurial endeavor was buying fidget spinners at a convenience store for $3 each, spray painting them gold and then selling them to his fifth-grade classmates for $7.

In 2017, the year he turned 12, he was horrified to hear about teens just a little older than he was getting caught up in violence in Philadelphia. "I wanted to be a light to the youth," says Brown. He came up with a plan to show other kids there was an alternative path: He'd start a clothing line.

He saved $178 of his birthday money and got his mom, Sherell Peterson, on board. "We just have to research it," decreed Peterson, who used to sew and sell custom-made clothes herself. Right away, Brown sent an Instagram direct message to Nehemiah Davis, a Philadelphia philanthropist who had created an online program on how to launch a T-shirt business. Brown spent hours watching the course, along with countless YouTube videos.

"I kept walking past his room and saw he was taking notes. He was so into it," says Peterson, who was impressed to hear Brown considering which logo color would command the most attention. He settled on the image of a bright yellow lion alongside a brand name that combined two of his favorite things: "sports" and "heroes." "Not superheroes, positive people I look up to," explains Brown, who tacked on "go" at the end for "go-getters." He pestered his mom to take him to a store to buy plain white T-shirts, and then to a print shop he'd found online.

On Martin Luther King Jr. Day 2018, he officially launched Spergo with 16 shirts that he sold to friends and family. "He made $280 from the sales," Peterson says. "So I said, 'Well, Trey, what are you going to buy with that?' He looked at me like I was crazy." Brown put the money back into the business - he made more shirts and got more serious about marketing.

Because Davis's course had suggested advertising in barbershops, Brown woke up early on Saturdays to hit the circuit. "His pitch got better and better," Peterson says. "These men were mentoring him on the spot - 'Speak a little louder,' 'Say this.' And everyone was buying shirts."

As Brown looked for new ways to make sales and spread the word about Spergo, he kept track of when concerts and events were happening around town, and he made friends with promoters. "I made sure I was always there. I would sneak in and have a bag of Spergo with me," says Brown, who used the encounters to give sweatsuits to celebrities and pump up his social media presence. (Now more than 91,000 Instagrammers follow his account, @ceotreybrown.)

By 2019, Brown was everywhere. Investment management firm Invesco featured Brown's story in a documentary-style commercial that aired in heavy rotation on CNN, and Brown soon beamed from an Invesco billboard over Times Square in New York. Peterson had to leave her job as an elementary school teacher to help Brown run the business - and drive him to his media appearances and speaking gigs. In December of that year, Spergo had its best month ever, earning $82,000.

In early 2020, on a whim, Brown suggested they fly to Miami for Super Bowl weekend. They headed down with three suitcases of Spergo gear that they fruitlessly dragged around their first day in South Beach. It all felt like a mistake until Brown saw that Sean "Diddy" Combs was in town. Through connections, they had previously texted. So, Brown FaceTimed him. "Trey said, 'You're the only person in Miami without Spergo on,' " Peterson remembers. "And Diddy said, 'Well, bring it to me.' "

They hopped in a car and went directly to the music mogul's mansion on Star Island. "Sean comes down and says, 'Man, you are determined. You never gave up. You remind me of me,' " Peterson recalls. A few weeks later, Combs presented his first-ever Black Excellence Entrepreneurial grant - for $25,000 - to Brown in Los Angeles, where the duo taped a segment for "The Ellen DeGeneres Show."

That period of travel and excitement was a whirlwind - until it ended with Brown hospitalized for more than a month. "My doctors said you need to rest your body," explains Brown, who was so hyped up that he couldn't get himself to sleep and had a seizure.

Through his recovery, Brown craved getting back to work. He released a self-published book, "Trey's Way: My Entrepreneurial Keys to Success," which outlines his advice for kids hoping to follow in his footsteps. (Some pointers: "Instagram is the best platform for young entrepreneurs." "Everyone has their own genius. It's just about learning what genius you have.") He also spoke frequently with his dozens of mentors, who helped him set his sights on opening the first Spergo store.

By July 2020, Spergo was in business in Philly, and Brown was back to feeling like himself. It marked a new chapter for the brand, says Peterson, who has helped hire a team of staff members to balance the workload. She makes sure Brown still takes time to be a kid. "He hangs out with his friends, goes to the studio and records songs," she says. And his daily schedule always includes a trip to the gym to play basketball, his favorite sport.

In fact, it's from hanging out at Philadelphia 76ers games that Brown helped land Spergo's latest deal. Marquise Watson, corporate partnerships manager for the team, remembers the first time someone pointed out Brown. "He was wearing his clothing, and he had this aura around him," says Watson. "The first thing that drew me in is how serious he was. This whole journey he's on, you feel like you're a part of it. He's like Philly: grit, grind, resiliency, brotherly love. It's infectious."

When the 76ers announced a new initiative this year to support local Black-owned businesses, Brown was one of the people Watson encouraged to apply. Of the 700 companies interested in the opportunity, Spergo was one of two selected for the "Buy Black Program." Conceived as part of a larger strategy to combat racial injustice, the program uses the team's marketing platform and resources to boost visibility and sales for its partners, explains David Gould, the 76ers' chief diversity and impact officer. Brown's message of empowering youth through fashion felt like a particularly good fit. "He's intentional about being a positive role model for his community," says Gould.

Brown is endlessly appreciative of his hometown, and how the people there have rallied behind his business. "Philadelphia has played a big part in Spergo, showed me a lot of love," he says. "It's a dream come true, and this is only beginning."

Now Brown is looking forward to building Spergo into a global brand, with stores not just in the Philadelphia and D.C. areas, but also across the country and overseas. And he's designing a new product that could take Spergo further than ever: sneakers.