"That whole audition process is pretty crazy," Momoa told Tonight Show host Jimmy Fallon. "Zack was a huge fan of Game of Thrones. A lot of people are huge fans of Game of Thrones. Zack was the one that... I couldn't get a job and Zack called me in. He was a huge fan and he wanted to take Aquaman and... It was funny because I had no idea what I was even playing. He just called me in. I had an audition for Batman. Obviously, Ben was cast. I was like, 'I'm just basically gonna be the bad guy. I'm gonna fight Batman and Superman. I'm gonna play the villain.' And he's like, 'Wait, no. Aquaman!'"
The rest is history. Momoa became Aquaman and has not looked back since first appearing in Batman v Superman: Dawn of Justice and reprising his role in the ensemble Justice League flick. Still, the best is yet to come for Momoa's aquatic DC Comics hero as his standalone Aquaman movie will arrive in December of 2018.
"He really was this outsider and lived on the fringes of society," Momoa told ComicBook.com in an exclusive interview. "We talked about him just being raised with his father, this blue collar worker. His father was a lighthouse keeper, but I probably worked on oil rigs. I'd be underwater and I could just rip the rig off and just weld."
According to the actor, saving the world in Justice League is merely the equivalent to "a weekend" in the character's life. "And that was when I was alone," Momoa adds.. "There's people that I would save, that I could save, and there's people that I couldn't. The human side of me is that heartbreak of he couldn't save someone. Not knowing what to with these powers, he was a drinker. He'd just down that emotion. He couldn't ever get that out.
"You're going to see that I really wanted him to be that gruff thing, because he has to become king. If Justice League is like seeing him at his lowest, and not just his lowest, but this loneliness that I wanted about him, so when we get to Aquaman you know why he became that, and how he had been put in that lonely spot.
"And how he has to bring these two worlds together. Because you're going to see this ocean world, which we just pollute, and how do these people feel underwater with what the land does to the ocean. And this war that is going to come between the two, and I'm the only one that can link the two. He has to do it. He doesn't want to do it."
Aquaman hits theaters December 21, 2018.