Aquaman may be the biggest surprise of the DC Extended Universe. Starring Jason Momoa as the titular hero, the underwater hero's 2018 solo film earned over $1 billion at the box office and became the most successful film focused on a DC superhero. Now, Aquaman is back for another big-screen adventure, with Director James Wan returning for Aquaman and the Lost Kingdom.

Years after the events of the first film, Arthur Curry is the King of Atlantis and a family man. While juggling his royal duties and his responsibilities as a husband and father, Aquaman faces an old enemy -- who has found a weapon that could destroy everything he loves. At a Q&A attended by members of the press (including CBR), Wan broke down Black Manta's evolution, the influence the canceled spin-off The Trench had on the movie, the tricky relationship between Aquaman and his brother, and just how weird the film is willing to get.

RELATED: James Wan Talks Batman Rumors in Aquaman and the Lost Kingdom

With the cinematic DC Universe in flux, as it shifts from Zack Snyder's incarnation to James Gunn's vision of the future, Wan reveled in the benefits of being mostly removed from the rest of the universe. "I'm aware of everything that's happening around me. I mean, I use the analogy that I'm living in a house that's getting renovated. It's hard to not be aware of the renovation that's happening around me. But the beauty about Aquaman is that we've always designed these two films to be within their own world. The advantage of not being hooked into this bigger universe is [that] whatever happens over there doesn't really affect my movie. This film doesn't hook into anything. It lives in its own world. That's what we found worked really well for us on the first film, and we're doing exactly the same. There's noise going around, but I'm just in my cocoon, in my underwater kingdom."

Aquaman and the Lost Kingdom Movie Poster

As a result, Aquaman and The Lost Kingdom follows the direction Wan had in mind all along. Comparing the previous Aquaman film to a romantic action adventure in the spirit of Romancing the Stone, Wan revealed that the second film was always meant to focus more on the relationship between Aquaman and Patrick Wilson's Orm. The villainous half-brother of Arthur Curry, Orm -- otherwise known as Ocean-Master -- was the villain of the prior film. In the first movie's climax, he was defeated and imprisoned for his crimes. "That's why I didn't want to kill him at the end of the first movie," Wan explained. "Because he was going to ultimately be a pseudo-antihero in this one. I wanted to see the relationship between Jason and Patrick. These two are really great in the film. They've got such great camaraderie, such good chemistry. The second one [is] a bromance movie... It's really kind of like Tango and Cash. That was the spirit that we were going for."

This shift in focus does mean Mera won't be as prominent in the film as she was in Aquaman. According to Wan, that was always an expectation for the film. "Mera is obviously a massive character in the comic books. We want to be respectful to the character of Mera. That's the bottom line. I want to be respectful to all the characters in this and try to do everyone justice. But at the end of the day, I have this story to tell, but I have so many other characters to serve. I felt like I had told Arthur and Mera's story in the first one. Now, I can focus on Arthur and Orm. It's a journey movie with these two, and the other characters sort of pepper their world, if you will."

Orm and Arthur in Aquaman and the Lost Kingdom

Wilson returns for the role of Orm, and Wan was quick to describe their working relationship as an ideal one for the film's approach to the character. "The great thing is, Patrick is such an amazing actor. There's a reason why I kept working with Patrick Wilson. He's so versatile... Patrick and I have such a close relationship that we can trust each other with how we approach the characters that he plays. One of the things we wanted to do with this one is that he was the bad guy in the first movie, and even though he's working with Arthur in this one, it's very important to remember where he came from.

"There's still antagonism between the two of them throughout the whole movie -- which is actually where some of the fun derives from. Seeing the two of them bicker. But at the same time, leaning on the more human aspect of his character. If you look at him in the first film, he was just trying to do what was right for his people. From that perspective, he doesn't see himself as a bad guy, so to speak. He's just trying to protect his people. I think because of that, Arthur kind of respects that. Arthur is so much about the family, about the family dynamic. We touched a bit on it in the first film, with how he's always wanted to reach out to his younger brother and try and build a relationship. Well, he gets to do that in this film." Meanwhile, Nicole Kidman's Atlanna returns as the "right hand of the King" while wrestling with the relationship she has with her sons.

RELATED: Aquaman 2 May Be Setting Up Arthur Curry's Greatest Tragedy

Black Manta in Aquaman and the Lost Kingdom

Ocean-Master may not be the main threat of Aquaman's latest adventure, but it's opened up room for another classic villain to step up in a big way. The trailer for Aquaman and The Lost Kingdom highlighted Yahya Abdul-Mateen II's Black Manta as the primary antagonist. Having claimed the Black Trident and all the power that comes with it, the villain is finally capable of not just bringing down Aquaman but all of Atlantis with him. As Wan explained, "If you're an Aquaman fan, you obviously know that Black Manta is a big nemesis of Aquaman. My plan with the first movie was always to set up a relationship with him and Aquaman. He was kind of a glorified side character in the first one. But we knew that that was going to be okay because we knew that the second movie was where we could go with him in a much bigger role." Wan teased that the discovery of the Black Trident was a happy accident for the villain, as he sought a means to empower his damaged suit from the previous film.

Wan confirmed that elements of The Lost Kingdom's story originated in The Trench, the since-cancelled Aquaman spin-off film -- and revealed more about the nature of that shelved project. "We had developed The Trench movie, and like most things you develop, if they work out? Great. If they don't? That's fine as well. We wouldn't want that project to potentially step on the Aquaman films. But we came up with a lot of really interesting ideas and really cool stuff that I felt we could use in this one. The Trench was going to be a secret Black Manta movie. Initially, we announced it as a Trench movie. But ultimately, we wanted to surprise the fans because it was going to be a standalone Black Manta movie. When that didn't happen, some of those ideas kind of found their way into this."

Jason Momoa and James Wan during the filming of Aquaman and the Lost Kingdom

The previous Aquaman was a gloriously unique film, a colorful burst of bombast that brought Julie Andrews-voiced kaiju and drum-playing octopuses to the big screen. That embrace of overt weirdness carries over to the new film, and Wan is happy to do so. "I've never been shy of leaning weird. Very early on, when I was given a few properties to look at, I picked this one because I felt like I could really lean into that quirkiness, that weirdness, and have fun with it. Seeing how much people enjoyed that in the first film gave me more confidence to lean into that in this one. The trailer doesn't quite touch on it, but there [are] a lot of really quirky underwater characters in this one." Wan also confirmed that Topo, Aquaman's Silver Age animal sidekick, does indeed have a "bigger role" in this film after his memorable cameo in the prior movie. That embrace of classic elements is clear in the designs of the film as well, with Wan drawing attention to the Silver Age inspiration in the aesthetics of the movie. "It's very retro-looking."

For all the big monsters and dangerous villains, Wan made it clear that the film does try to speak to the state of the world as it stands. Specifically, Wan was excited to bring focus to the stakes the world faces through ecological disasters amid climate change. "Aquaman has always been about the environment -- more than any of the other superhero characters. We wanted to lean into the environmental aspect of this movie. So we wanted the second film to still be fun, really adventurous, colorful, and everything like the first film, but we want to have a little bit more to say -- something a little bit more grown-up. We do have something important to say. This was one of the hottest summers we've ever experienced, right? Not just in the US, but everywhere around the world. We really do lean into that. The environment is shifting very much in this movie. Arthur needs to be able to work with his brother to try and stop this from spiraling into a complete catastrophe. We don't want it to be too preachy, but we're definitely not shy about it. I think that's something that we need to talk about, even in the context of a fun adventure movie."

Even ahead of the new film, Wan has one eye on the future. When asked if there were ideas for further adventures of Arthur Curry, Wan revealed that "Aquaman definitely has more places to go. I don't know how to answer that more without giving things away. Because where we go at the end of this movie, it does tee up something bigger. It does tee up a new direction for Arthur's story."

Aquaman and the Lost Kingdom opens in theaters Dec. 20.