When you're the second person to portray one of science fiction's iconic characters, Chris Pine notes, it's easy to second-guess yourself about nearly everything. The American actor should know, having inherited the role of the USS Enterprise's Captain James T. Kirk in the Star Trek universe from William Shatner. Millions of dedicated Trekkies have kept the internet afloat with their views on him as Shatner's successor.
Pine went a long way to making the part his own with a swaggering, committed take on the 23rd-century hero in director J.J. Abrams' highly successful 2009 Star Trek reboot, but four years, and one highly anticipated sequel in Star Trek: Into Darkness later, he says his response to donning Kirk's trademark Starfleet uniform is still essentially the same.
''The first thought is always don't screw it up,'' says Pine, who was in Sydney last week along with his director and several of his co-stars for the world premiere of the new movie.
''There's plenty to look forward to, but you always start with don't screw it up.''
The un-Hollywood-like gap between the two films – ''we didn't just churn another one out because people wanted it,'' Zachary Quinto, who took over the equally famous role of Spock, says – has paid off. At a time where too many sequels are almost mechanical in repeating their initially successful elements, Star Trek: Into Darkness clearly furthers what has already been achieved.
''It has really big Greek themes about life and about your own mortality,'' Pine says. ''The brash, young punk upstart of a kid in the first one really gets to explore deeper, darker and more vulnerable parts of himself. We were ambitious with what we wanted to achieve not just visually, but also thematically.''
By retaining not only Abrams, but also the same writers, the new film is able to take established elements and twist them about.
In a plot that focuses on the pursuit across the galaxy of a terrorist, John Harrison (Sherlock star Benedict Cumberbatch, oozing malevolence), Kirk's cockiness becomes his downfall while Spock has to address the emotions that reside beneath his coldly logical outlook.
That belated growing up for Kirk brings the character somewhat closer to Pine. The 32-year-old, who wasn't a Star Trek devotee before securing the role, is more insular than his alter-ego. Kirk favours bar fights and girls who are literally off the planet, while Pine is more likely to be reading Viktor Frankl's psychiatric memoir Man's Search for Meaning or an examination of drone warfare.
A Los Angeles native with an English degree from Berkeley who periodically dips into edgier theatre work, Pine has experienced successes (2010's Unstoppable, alongside Denzel Washington) and failures (2012's interminable This Means War) in the wake of his ascendancy with Star Trek, but he remains the most low-profile leading man in Hollywood. Pine is the rare member of the young Hollywood set who doesn't feel the need to exhibit himself in the VIP section at the Coachella music festival.
''I hope it stays that way,'' Pine says. ''More than anything, what we do as actors is to sit and watch and I would never want to get so lost in the celebrity bubble that I couldn't do that because my feet no longer touch the ground.''
He attributes a good proportion of his grounding to his family background. Pine is third-generation Hollywood actor. His maternal grandmother, Anne Gwynne, was under contract at Universal Pictures in the 1940s, while his father, Robert Pine, has been a working actor for almost 50 years. The movie business holds few illusions for Chris.
''I grew up in a house where my father went on auditions and he got some and he lost some and there were good years and lean years,'' he says. ''I didn't expect anything from the business and that's often a danger in Hollywood, the notion that if you're pretty and have white teeth and just show up for the game then you'll win. That could not be further from the truth.''
While both Pine and Quinto separately invoke the defining spirit of Gene Roddenberry, who created the original Star Trek television series in 1966, the distinct bond between the new cast is noticeable.
The two actors use joint interviews as an excuse to swap jokes, while one of the funniest lines from the film was an improvised dig English comic Simon Pegg, as chief engineer Scotty, threw at Pine, who promptly cracked up.
The camaraderie between the ensemble cast will be affected by the departure of Abrams, who is trading Star Trek for Star Wars to direct the 2015 sequel to Return of the Jedi, but Pine believes the cast's commitment to each other and the movie's human qualities will prevail.
''This is not some guy in a superhero's mask – there's no Batman, no Superman,'' Pine notes, talking as much about the real world as the fictional one.
''Star Trek is about a bunch of disparate people and what they're capable of when they work together.''
Salute to a highly logical friendship
The relationship between Captain Kirk and his half-Vulcan science officer, Mr Spock, has long been at the centre of Star Trek's complex dynamic, and in expanding that for the rebooted movies, Chris Pine and Zachary Quinto have added a degree of humour and a friendship that has grown on and off the screen.
''During filming I looked around at friends and co-stars and realised that these are people who, whether we make four more or no more Star Trek movies, will always be in each other's lives,'' Quinto says. ''There's something profound about that and it's something I plugged into for crucial moments between Spock and Kirk.''
Quinto has seamlessly made Spock's pointy ears and striking intellect his own, complete with the blessing of his predecessor, Leonard Nimoy, but he's still surprised at the level of cultural recognition Spock carries. When Quinto campaigned for Barack Obama last year he was among a group of volunteers who met the US President, who sighted Quinto and promptly gave him Spock's Vulcan salute.
''You couldn't make that up,'' Quinto says. ''I've always been ambitious but I never imagined that I would be doing this level of work and be so fulfilled.''
And did he respond to Obama? ''I was right back at him,'' Quinto laughs.