Can robots have a coming of age story? Well, Optimus Prime, Megatron and their assembled mechanical factions are alien robots known as Transformers, so, you know, anything is possible. And indeed, Transformers One takes us back to a time before sides had been taken in the war between the Autobots and Decepticons, when Optimus was known as Orion Pax, and Megatron went by the slightly less imposing moniker of D-16.

The animated adventure, directed by Toy Story 4's Josh Cooley, harkens back to the 1986 Transformers: The Movie, but is set even further back in time, when Cybertron holds secrets and threats – compelling Orion, D-16, B-127 (AKA Bumblebee) and their friend Elita-1 to become what they're supposed to be. They're about to go through a – pun entirely intended – transformational experience.

With the first trailer now online, Empire spoke to Cooley about taking on the challenge of directing a new Transformers story, figuring out the scope and scale, and whether he's worried about having someone other than Peter Cullen voice Optimus…

Go, Bots

Cooley – who spent years at Pixar working on the likes of The Incredibles, Up, Inside Out, before stepping up to direct Toy Story 4 – here embraces the chance to let his inner Transformers fan boy out, working from a screenplay by Andrew Barrer and Gabriel Ferrari. "When I first read the script, with it being an origin story for these characters that people know and love already, I never felt nervous about it," he says. "It was more, 'I want to see this…' So, it was an easy decision. And also the fact that everybody who touched this film was such a fan and just brought so much love and care and respect to these characters. There's a lot of real fan love that went into this."

Man Or Machine

We've spent years watching live-action/CG Transformers movies, where the tone is weighted more towards the action and high stakes than knockabout laughs (though the balance is perhaps more even in Bumblebee). For Cooley, the chance here was to inject more comedy and humanity into the characters, even as there are zero humans to be found. "In the live-action movies, it's a fish-out-of-water story. You've got these huge Transformers compared to humans, so there's comedy there. We didn't have any of that, as the movie takes place millions of years before Earth even exists," he says. "We needed to make sure that our characters alone could carry the film, and had humour and emotion. There was a lot of figuring out how to make our robots a little more human. Even in their designs, making sure that their faces weren't covered all the time. The eyes still felt robotic, but had a lot of expression to them. I really wanted to have a tone to this that is not as intense right away. In the trailer, you do see a lot of fun in the film. And then it gets really exciting…"

Prime Factors

Peter Cullen may not have the monopoly on voicing Optimus Prime (Alan Tudyk and Jon Bailey are among those who have taken on the gig at different times), but his gravelly, authoritative tones are surely what most people hear when they think of the Autobot commander. How, then, do you find someone to play Orion Pax in the time before he assumes the mantle of Optimus? For Cooley, the choice was a Marvel hero.

"From day one that was my big question. 'How the hell do you do younger Optimus Prime?' It's gotta be believable as a character that you can totally buy will eventually become Optimus Prime and hold those qualities of him," he explains. "It really weighed on me for a while because I was [thinking], 'If we don't find that, I don't know if it's gonna work.' And when we heard Chris [Hemsworth], and I talked to him, I was blown away. In the first recording session we chatted for a long time, and he started finding the voice. I got chills just hearing him read some of the lines. It felt right."

Pre-Megatron

Alongside Optimus, you've got D-16, the 'bot who will be Megatron. Though Frank Welker has most closely been associated with the role in the past, Cooley went for Brian Tyree Henry to take on the character, looking to find someone who could play a villain before his turn to a darker viewpoint. "I talked with Brian a lot about this early on," Cooley says. "I didn't want him to be just the bad guy. I wanted this film to work for somebody who had no idea what Transformers was. If they were to come into this cold, they would not know that he was going to be a bad guy. It was important to me that, once he started to turn, the audience was right there along with him, and felt for him, and understood where he was coming from. There's tragedy here, watching this friendship fall apart."

BumbleKey

Movie audiences primarily know Bumblebee as a character without his own voice – usually employing radio broadcasts to stand in for his statements. Cooley looked to go back to the chattier character from the animated series and other media. "I thought it was brilliant in the live-action to have him not be able to speak, and to use the Earth radio for dialogue," Cooley admits. "But here I said, 'Well, what's the opposite of that? It'd be somebody who never stops talking. Who would I love to hear from as that character? Keegan-Michael Key!' I've worked with him before. And he's just naturally just so appealing and likable. He was always my number one choice for Bumblebee."

The one downside to hiring a consummate improv performer for the role? Outtakes! "There are more than several hours of extra lines," Cooley laughs. "He can take the idea of a scene and just go with it. And at that point, I felt like my job is just to not step on it by breaking." Not so easy when you're the director in the room with him playing other roles… "I had to bite my arm to keep from laughing!"

Cybertron My Mind

If you've watched the 1986 animated effort Transformers: The Movie recently, or are old enough to remember when it came out in cinemas (don't mind us, just turning to dust over here), chances are you'll get a warm glow of recognition for the new movie's scope, scale and design aesthetic.

"It's always been in the back of my head," Cooley offers. "I think I saw it at a birthday party when I was maybe six. When I got the job on this, I went back and watched everything. And I had forgotten how, at the very beginning [of the animated movie], you do see a couple of shots of Cybertron when everything's great. It was really fascinating to see that. The movie has an epic quality to it with Unicron coming in, and I really wanted to capture [that]. With this film being CG, and taking place on Cybertron before things go south, I wanted that feeling of the original Transformers movie – but also something like Dune, with a scale just so massive and just so epic."

Ch-Ch-Ch-Ch-Changes

As the trailer specifically makes clear, the story starts before Orion, D-16 and co have earned the ability – or indeed, the right – to transform. Learning how that happened was part of the appeal for Cooley. "There's a specific reason why our characters can't transform at the beginning," he teases. "And so seeing them get that power and try to deal with it, I thought was really fascinating. That's something that's never been done in a Transformers film. I'm just using Spider-Man as example – he gets bit by a spider. But that doesn't he can do everything perfectly right away. There's fun in that learning process, and seeing them evolve over the course of the film. This felt like a perfect reason to do that."

Robots In Design

Given his background with Pixar (and his clear love for Transformers lore), Cooley – along with his team – has naturally sprinkled plenty of easter egg references for fans. "There are some designs within the sets that are references to very specific things that I think only the big fans would recognise right away," he smiles. "And what was great was my art team and my animators are all such big fans that they would throw out ideas: 'How about this or that?' And I'd tell them to go for it. So there are a lot of details in there that I think fans are gonna really love."

Transformers One will roll out to cinemas on 11 October.