Chris Hemsworth digs into origins of Optimus Prime and Megatron in 'Transformers One'

Chris Hemsworth wasn’t going to sign onto a Transformers movie just to keep the franchise going.

“We needed to find out something different about these characters and understand they were just regular guys with jobs in the mines,” he says.

Movie review: 'Transformers One' fills in the blanks

Pitched “Transformers One,” an origins story for Optimus Prime and Megatron, the one-time Thor thought it was a good opportunity to “dig in and invent.”

“We weren’t mimicking something that had been done before. This was a creation of our own and a collaboration, which I was really excited about,” Hemsworth says.

To make the concept work, producers talked to director Josh Cooley, who had won an Oscar for “Toy Story 4.”

Bringing that toy knowledge to the Transformers world made sense. “It’s all about scale,” Cooley says of the two concepts. “With Transformers, it’s all about shooting things so they feel much larger. It was really interesting not having humans in it. You kind of force yourself to create a scale that everything’s based on.”

For “Transformers One,” Cooley needed voice actors who could suggest the characters that ultimately appear in the “Transformers” television series and movies. Because the characters are miners just getting their start, they didn’t need those booming voices that have launched an industry.

“There was no pressure because we don’t know who they are as youth,” says Hemsworth, who voices Orion Pax, the future Optimus Prime. “For me, it was like, ‘We can go in and just play.’ I attacked it as a coming-of-age story. I thought of myself at 19, 20, 21 and what it was like to have my first job, follow the rules and keep my nose clean.”

For Brian Tyree Henry, who co-stars as D-16, the future Megatron, it was an opportunity to reconnect with childhood. “Transformers has always been a part of the fabric of my youth and my life,” he says. “What’s really cool is finding out the beginning of these two – where they started. It’s something I always wondered about.”

Orion and D-16, robots on the planet Cybertron, become friends and work to understand the company they work for and the world they’re in. Soon enough, they discover the secret to transforming and what lets some robots assume a greater role in their world.

Starting out, the two “have to have this youthfulness, this playfulness…and not be afraid of taking chances,” Hemsworth says. “Even though there are no humans on this planet, there’s still humanity within the characters.”

To get to that point, Cooley had to work backwards and understand how Optimus and Megatron got where most know them.

The key, he says, was having characters who didn’t transform, then discovered the secret.

A Transformers bible – which is used to keep filmmakers on track when they’re approaching the subject – gave Cooley plenty of background. “Most of the stories are when they come to Earth,” he explains. “But there is like billions and billions of years before that and millions and billions after that. I had no idea there was this big Tolkien-length lore that’s been created over the years. When they handed that to me, I was making sure they were clear that this was not all going to fit in a 90-minute movie.”

For the voice actors, “Transformers One” was an opportunity to pay tribute to their heroes. For Hemsworth, that’s his father and professional surfer Kelly Slater. For Henry, it was Kwame from “Captain Planet.” “I was like, ‘We can save the planet’ and we get really cool rings,” Henry explains. “I never wanted to be Captain Planet, though. He’s blue with green hair. But we need Captain Planet now more than ever.”

When they saw what “Transformers One” was pitching, the two were in. “Listening to your heart, your inner calling, resonates throughout this film very heavily,” Hemsworth says. “That’s always been something that I live my life by.”

The concept of destiny struck Henry. “Destiny breeds hope,” he says. “What was crazy about this movie is how much the parallels reflected my coming of age – the concept of identity, friendship and the concept of what’s right and what’s wrong.

“There are so many different beginnings we go through in our life, if we’re lucky,” Henry adds.

Says Cooley: “We’re all in the same place, no matter what we look like or what we believe. Sometimes people forget that, so that’s one of the things I’m proud of.”