A quick trip to YouTube will confirm, to anyone in any doubt, just how hotly contested the casting of Brenda, in Maze Runner: The Scorch Trials, was. After the New York Times bestselling book series, and a first feature that clocked up more than $300m in global box office receipts, there were lots of voices ready to have their say. The video site is full to bursting with casting rumours, fan commentary and even auditions, as Maze Runner fandom the world over wondered who would wind up with the role.

Rosa Salazar in Maze Runner: The Scorch Trials

Rosa Salazar in Maze Runner: The Scorch Trials

Step forward Rosa Salazar. If she feels the pressure of fan expectation, it doesn't show. On the film's set in Albuquerque, New Mexico, the first sound you hear is her laughter, and as she plays out a scene with Dylan O'Brien's Thomas, Brenda comes to life.

"I feel like I am Brenda," she announces, as she takes time out to talk about the role. "Like me, she had a rough start. She watched her brother get taken away and her father die. She went out into this wasteland at a very young age and just sort of had to survive."

Salazar can relate. Despite a burgeoning movie career that seems certain to put her on the A-list, a little over a decade ago life was very different. "I was emancipated at 15, I went to school and had a full-time job and apartment, and ever since I've been on my own, parenting myself. What happened is I developed this hard exterior. No one could get through this impenetrable armour, or so I thought."

This is Brenda's experience until she meets Thomas. "He sort of yanks it out her," continues Salazar. "She's forced into this position where she has to be vulnerable for the first time in a very long time and I totally get that about her. It's what I was attracted to. She's flawed, and I really liked that. People who face some sort of adversity are the kinds of people I'm attracted to in my own life. It builds character."

She auditioned for the role whilst The Maze Runner was still in cinemas, and resisted going to see it until after she'd tested with O'Brien. "I did go and see the movie right after the audition," she remembers. "I was like, 'Oh, I hope this is good!' And then it blew me away. I was immediately calling my manager, like, 'Did I get it? Did I get it?'"

In fact, the process of searching for Brenda had started much earlier, whilst the finishing touches were still being applied to the first film. "We started in early Summer of 2014," says producer Wyck Godfrey. "In all of our roles we didn't feel like we had to cast movie stars. We just wanted good actors. We want people to immerse themselves totally in the fantasy of the film."

For O'Brien, Salazar had what it took to fit this brief the moment she walked in the room. "I always had so much trouble picturing Brenda from the book," he recalls. "I don't know why, but I could never really form a definitive image of her. But when I read with Rosa it was just like, 'Oh, that's it.' She fit right in immediately."

"Joining the cast has been so easy," reflects Salazar. "It's not always like that; it's not easy to join a fully formed ensemble. But this one wasn't just easy; it made so much sense. We all have the same sense of humour and everyone gets along. There's genuine affection for each other."

Her relationship with O'Brien has been particularly close, with the characters sharing most scenes together. "In the book, Brenda's really fast with Thomas," Salazar laughs. "She's like, 'Let's make out. That's where I'm from.' She immediately feels an attraction to Thomas."

But Salazar suggests their relationship is very different from Thomas's relationship with Teresa, played by Kaya Scodelario. "Thomas and Teresa are thrust together in the moment and it's very obvious that they might become a couple, but the movie's very smart about not making it about that. Thomas and Brenda have this beautiful exchange. They're almost equals and they challenge each other, which I think is really hot. She's no damsel in distress, and she's going to give him a run for his money. The moment I met Dylan it was like, 'OK, we can spar together.'"

Says Scodelario: "There's a natural mistrust between Teresa and Brenda, but I was very passionate about not making it girl-hates-girl. I don't think that rivalry makes any sense. It's not the warmest relationship, but it's definitely not a rivalry and there's no tension between them as people."

Maze Runner: The Scorch Trials is undoubtedly the biggest role Salazar has landed to date, but her career has developed swiftly, with standout performances in the likes of American Horror Story and Parenthood.

It was high school drama that instilled in Salazar the drive to become an actress. When the news broke about her casting in the latter television show, she remembers an email from an old teacher that read, "I'm so happy you're alive." The teenage Salazar was an unruly student. "Everything was an escape for me when I was younger," she reflects. "I had a tumultuous home life thanks to the unsavoury characters my mom would marry. My brother just sort of evaded and my dad lived far away, so I was left alone. I never thought it would end up like this."

She was faced with two stark choices: "I thought, OK, I'm either going to start doing hard drugs, get pregnant and just be here living some kind of life, or I can actually give it a go. And it was actually easier for me, because I'd faced a number of deep, emotional issues in my life, to go, 'Well, I've got nothing to lose.'"

She had been skipping school regularly, and getting ready to drop out without her diploma when her drama teacher, Bob Garman, sat her down. "He said, 'What are you doing? You're so stupid; smoking cigarettes and skipping classes.' I really, really liked his class and I didn't even know why at the time. He said, 'What's going on with you?' And he actually listened to me. This one person sat me down and asked me questions instead of just yelling."

Garman encouraged Salazar to try out for the after-school improv team, and after initially being amused by her fellow students' auditions, she was soon won over, and aced her own piece. "I have Bob Garman to thank for that thrust into acting, and there are lots of Bob Garmans along the way. People who paid for classes when I couldn't, and people who gave me jobs."

All of this life experience is reflected in Brenda, and doubtless informed the filmmakers' casting decision. "I hadn't heard the name Rosa Salazar before her audition," admits Godfrey. "But in her audition she blew us away. She's this force of energy and she very much encapsulates Brenda's spirit."

Salazar is aware, she says, of the intense fan interest in her casting, and feels the responsibility of doing right by the character. And she's well aware that there are question marks over her short haircut. "In the book Brenda is introduced as a girl with long, brown hair," she explains. "And trust me, the fans have let me know about that part of the book, because they've been reaching out on Twitter."

But she's sure they'll like the result. "When they see the movie it'll make sense. She's very no-nonsense as a character, and this haircut is very no-nonsense. There's nothing to hide behind. Before this summer I had long hair down to my waist, and I would hide my face a little bit and have this kind of grungy attitude. When you chop it all off, it's like, there's your face, and that's it."

So passionate was Salazar to create the perfect Brenda that she spent lots of time working with the costume department on her look. "Everything from the way I run to the way I jump, the jacket we chose informed that. It flows and has a femininity to it."

The completed look reflects one of her sci-fi heroines - Sigourney Weaver in Alien 3. "I also loved Noomi Rapace in Prometheus. She's such a badass in that movie. I'm a huge sci-fi fan and a fan of badass women. Sigourney Weaver was my number one influence. I wanted to be that, and I wanted to kick ass and still be feminine while doing it."

As she goes for another take on set, she appears to have figured out how to get there.

By Joe Utichi - www.joeutichi.com

Maze Runner: The Scorch Trials is out now on Digital HD and out on Blu-ray & DVD 1st February