Montville — Kristiyana Petrova talks and acts more like an adult than most people do, even after they’ve had their whole lives to learn how to be an adult.

She approaches every interaction like a job interview, statistics and anecdotes pouring out of her, each rattled off to convince you, quickly, that she deserves your respect.

One of those anecdotes is about cheesecake.

During Petrova's freshman year at Montville High School, the lacrosse team was selling cheesecakes as a fundraiser to pay for new warm-up uniforms. Frozen cheesecakes, about the size of your hand, $20 each. Petrova and the other members of the team were supposed to sell eight.

Petrova had never sold anything before, but in some ways she had everything she needed to be good at it. She has the personality, to start. Even before she moved from Bulgaria with her mother, she was the kid who sang and danced in the middle of family gatherings, loving every moment of the attention.

She has a gift for the superlative, too. For Petrova, everything is the biggest and best, and if it’s not, you might as well not mention it.

A trip to the Dominican Republic to take prom photos and visit her grandparents last month was “the best, best, best trip of my life.” Her mother, a former accountant who works at Foxwoods Resort and Casino as a housekeeper, graduated from “the best economic university in Bulgaria.” Petrova's part-time job helping with a mobile photo booth allows her to “make conversation with anybody about anything” – something she’s also good at, it turns out.

And, like any good salesperson, she can tell a story. The legend of the cheesecakes starts with Petrova going to her teachers and coaches first.

"I got here with the bus, really early," before all the other kids were driven to school, she mentions, in case you forgot that she does all this herself. "I had a whole spiel — it was right before Easter. I said 'these cheesecakes — there are so many flavors," she remembered, her breath quickening at the memory of her first sale. "Only 20 dollars. If you want to have dessert for Easter, this is going to be it. And you're going to be helping the lacrosse team."

Sold. Thirty, the first day.

Then — because why not — she tried the superintendent's office. And the cafeteria workers. More cheesecakes.

And of course, Petrova lives in an apartment building. And her mom, Petria Petrova, works at Foxwoods. So the neighbors and her mom's co-workers got cheesecakes too.

Petrova's voice speeds up and her eyes widen as she comes to the story's climax.

"In the end we sold 120 cheesecakes. And I said, 'I love doing this.'"

Petrova won a scholarship from the organization that ran the fundraiser because she sold more than anyone in New England. It is one of several that will help cover her tuition at Babson College.

"Because I was so passionate, not about cheesecakes — but selling them."

Petrova is the 7-year-old who learned English in six months because she was "frustrated" she couldn’t talk back to her classmates also came home from her first math class in the United States concerned that she had been placed in the wrong grade, because the other kids were learning addition when she had already mastered multiplication.

When school officials told 8-year-old Petrova that a parent or guardian had to come outside and meet her when the bus stopped to drop her off, she called it an "absurd" rule for someone who had walked home from school every day in Bulgaria.

She’s the same girl who tried out for the volleyball team, having never touched a volleyball, and ended up as the captain of the junior varsity team.

Who turned a cashier job at Rite Aid into three other jobs — tutoring, running the photo booth and filing papers at a car dealership.

Who bought herself a moped, and then a car, to get herself to work and sports practice and to bring her mom to work on days the SEAT bus schedule didn't match up with her work schedule. Who helped her mom study for the questions on her citizenship test that most U.S.-born Americans couldn't answer, then passed the test a year later herself.

And now she's the young woman who took pictures in her prom dress with her grandparents in the Dominican Republic because they couldn't get a visa in time to come to Montville to see her graduate. Who roots for both Bulgaria and the United States in the Olympics, because she's proud to be from both.

Who woke up at 5 a.m. on a recent morning to attend a Crossfit class — because she told a friend she would go with her — then went home to finish her homework, put on a bright orange dress to go to school, do an interview for the last of multiple college scholarships she's applied for, and then pick up her mom at work.

"It's 120 percent every day," said Jon Swift, a Rite Aid customer who ended up giving Petrova a job as a tutor for his daughter, as an assistant with his photo booth business, and doing paperwork at the Valenti Volkswagen dealership where he works.

At weddings and parties where they set up the photo booth and encourage people to pose with props and make silly faces, Petrova is a natural. If someone at a school dance is hanging on the wall, too nervous to dance, Petrova is the one to bring them out onto the floor.

"She'll just absolutely do it — there's no reservation, there's no 'I'll feel stupid,'" Swift said. "She doesn’t worry about what other people think of her."

Finding a new assistant when Petrova goes to Babson College to get a business degree in the fall will be hard, he said.

"I'm not going to find another Kristi," he said.

He's not the only one. Petrova and her mother sleep in the same room in their apartment. She texts her mom when she leaves for school and when she goes back home. It will be strange to be away from that room when she comes home after a day in class.

But Petrova said she knows this is why her mom brought her here.

"She's my best friend, and she sacrificed so much for me to be where I am," she said.

When she graduates from Montville High School on June 16, this is what her cap will say:

"My mom crossed an ocean so I could cross this stage."

m.shanahan@theday.com