Chai Hansen’s first acting job – at 24 years old – was the lead merman of ABC’s Mako Mermaids – a spin-off of H2O: Just Add Water that proved almost as enduring as the original worldwide hit.

“Whether I’ve got a shaved head or long hair or a moustache, people from all over the world recognise me from Mako,” says Hansen, sitting in a Sydney hotel room with a fresh buzz. “They just seem to love that character and show, which is awesome. It’s such a throwback.”

In the decade since, the Thai-Australian actor has hopped mostly between sci-fi and fantasy TV shows, both in the US (Shadowhunters, The 100, Night Sky) and at home (The New Legends of Monkey, We Were Tomorrow). He’s been a werewolf, monkey god, alien and all manner of fantasy heroes, building up a fan base of escapists and a quarter of a million Instagram followers in the process.

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But Hansen has returned to Earth in recent years. He’s appeared in several Australian shows, including comedy Population 11 and Netflix’s Apple Cider Vinegar, while his character Tim was a fan favourite for viewers of ABC’s acclaimed 1980s-set newsroom drama The Newsreader. (His portrayal of the sweet gay cameraman has led to the character being “shipped” with closeted anchor Dale via YouTube montages, set to Chappell Roan’s queer-pining anthem Good Luck, Babe!)

Not one of these transformations – not even filming in Sea World’s shark tank while wearing a 12-kilogram tail – was as challenging for the Thai-Australian actor as his role in Watching You, a tense six-part thriller set and filmed in Sydney and filled with plenty of duplicitous characters.

Loosely adapted from Kiwi author J. P. Pomare’s twist-filled novel The Last Guests, Watching You plays off a decidedly contemporary fear: what if your holiday rental is filled with secret security cameras? And, for extra drama, what if the voyeur caught proof of an affair?

Hansen’s quietly caustic role required the 36-year-old to connect to a side of himself he’d shut off: an inner rage. “It’s a very human thing; we shy away from our anger because we’re scared of what it can create, what can happen,” he says.

“That’s very true to who I am. I’ve been suppressing my anger for such a long time that I forget how to be angry. So to portray someone who releases it, you have to confront that in yourself.”

If Hansen still suppresses that anger, it does not creep into our conversation. He’s warm and earnest, far more than is usual for an interview, let alone the last of a press day. After our time wraps he keeps the conversation going, asking about films I love, and writing down any he hasn’t seen.

Despite that, he has a flight to catch – his suitcase is open on the floor as he’s making the final touches ahead of an overnighter to make the global premiere of Play Dirty in New York.

Directed and written by Shane Black (the creator of Lethal Weapon), Play Dirty is a heist caper that was shot in Sydney last year, starring Mark Wahlberg, LaKeith Stanfield and, a little down the call sheet, Hansen, as a dopey, often drunk getaway driver.

Currently the most-viewed film on Amazon Prime Video, it released the same week as Watching You’s first two episodes. “There’s a lot happening,” Hansen says, beaming.

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Created by Alexei Mizin and Ryan van Dijk, Watching You pares back Pomare’s intricate web of surveillance for a simpler, single storyline. As a result, it can be a little slow-paced, with much of the action – and violence – squished towards the end.

Luckily, the relationships are magnetic, in large part thanks to the cast, led by Aisha Dee (Apple Cider Vinegar, Safe Home). Dee plays Lina, a 30-something paramedic who bristles whenever her fiance Cain (Hansen) discusses the wedding or a future family. The two clearly need to talk but neither are willing.

Feeling smothered, Lina finds herself flirting at a party with beefy stranger Dan (Josh Helman), and the two head to a friend’s NestShare – an Airbnb equivalent – for a one-night stand. Soon Lina is blackmailed from an unknown number with footage of the affair and she’s left unsure whom to trust as Watching You builds a body count.

That distance only makes Cain more insecure, his relationship resentments bubbling up. “He has all these expectations on himself, based on what he thinks a masculine man needs to be in society,” says Hansen. “There’s this expectation for males to be stoic and not cry in front of people. So when the doors close on emotions, how do you release that energy?”

Playing that, though, didn’t come easy. “The question ‘How can I tackle anger?’ just kept coming up for me,” says Hansen. “I had that to really substitute quite a bit to get back into, you know, like old-school traumas that affected me back in the day that keep coming up but I’ve been suppressing for a long time. So to access some of those emotions, it was pretty confronting.”

The connection came from what – or who – was left out of the script.

“I realised Cain’s mum is there [in the show] but they don’t even talk about his dad. I was like, ‘Oh, I’ve been there, I know this’,” says Hansen. “Mine was more a specific story of neglect but the lack of a healthy masculine role model definitely played a part in who I saw myself as, as a man growing up. It was screaming at me.”

Born in Thailand to a Chinese-Thai father and Australian mother, Hansen spent the first seven years of his life living on Ko Pha Ngan, an island north of Ko Samui. He describes those early years in Thailand as immensely strict at home and school, vividly remembering the shame he felt messing up a speech in front of his class as a five-year-old.

“If we screwed up, the teacher would cane us,” he says. “That conditioned you to think if you f— up, you’re associating f—ing up with pain or fear. It was obviously a different time, a different era, and now it’s more of a free, open society. But back then it was very strict, and my dad’s parents were really strict on him, too. He repeated the pattern. So my mum took my sister and I here.”

The three of them moved just south of the Gold Coast, which proved a huge cultural shock.

Hansen struggled with English as his second language, repeating a year to catch up. Socially it wasn’t always easy, either – Hansen was incredibly shy and particularly hated public speaking.

“I was the Thai kid in an Australian school. But when I was in Thailand I was the Australian kid in the Thai school,” he says. “I had this consistent outcast mentality of ‘I never fit in anywhere’. But I think that really helped me, as my power to never fit into a box, and it pushed me to follow an artistic career. So I kind of have that to thank.”

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Acting didn’t come immediately, with Hansen pursuing athletics, at one time training to be a triple-jump Olympian before discovering breakdancing. After school he won a full scholarship to Queensland dance school DLDC and “lapped up” the weekly acting class, later moving to Sydney and taking part in a street-dance show before heading back north for Mako.

In the decade since, he’s travelled through time and space (separate shows) and fought demons and wars in a post-apocalyptic Earth where only pretty 20-somethings playing teenagers remain.

Together, these sets were a kind of professional education for Hansen, though he admits some of the larger productions could leave you feeling “like a cog in a machine”.

“You’re there to play a part, then you get the f— out of there,” he says. “But I learned a lot.”

Hansen isn’t saying no to sci-fi forever, though. He hopes to keep exploring new facets, having recently written a screenplay in the hopes of one day directing.

“So much of what I’ve played so far has been so devoid of myself,” he says. “It’s been a fantasy. [But] I just love playing roles that are so contrasted to who I am because I get to experience and learn who I am as well,” he says. “What are the boundaries?”

Watching You is now streaming on Stan, which is owned by Nine, the publisher of this masthead.

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