Bruce Wayne is not Batman–at least not in Aztec Batman: Clash of Empires. DC’s new animated film tells the story of Yohualli Coatl, an Aztec boy whose father is murdered by Spanish conquistadors in Hernán Cortés’ entourage, on his hunt for revenge. The tale reinvents classic Batman rogues including Poison Ivy, Catwoman, and the Joker (in Aztec Batman, Yoka).

ScreenRant’s Aztec Batman: Clash of Empires review states the setting and time period for the film “could not have been more right,” and one of the movie’s elements that creates the kind of harmony behind its success is undoubtedly its musical score. That comes courtesy of The Cuphead Show! and SpongeBob SquarePants composer Ego Plum.

For ScreenRant, Ego Plum discussed his bold musical decisions for the very much R-rated Aztec Batman: Clash of Empires and why punk drums and loud guitars actually are in the Aztec spirit. Plus, the composer revealed how his personal relationship with Batman (1989) composer Danny Elfman came in handy.

Ego Plum Could Do No Wrong On Aztec Batman: Clash Of Empires

Ego Plum could have felt very constrained scoring Aztec Batman: Clash of Empires. Despite being a tale of gods and monsters that reimagined Hernán Cortés as Batman villain Two-Face, the movie also chased historical accuracy to a remarkable extent. “They had to hire actual consultants and even check with the Mexican government to get approval of certain things,” Plum said.

Pair that with the long musical legacy of Batman as a character, and it’s easy to imagine Plum being beholden to both traditional Aztec music and the established Batman scores of composers like Danny Elfman and Hans Zimmer. But the composer had a specific mindset that served him well.

“I come from punk rock,” Plum said on a Zoom call shortly before the release of Aztec Batman: Clash of Empires, “I am irreverent in the way I approach music.” “I never learned how to read or write music, [and] everything I liked [was from] people that didn’t know how to play instruments–people that were breaking rules.”

So, while Plum did do research (noting, sadly, that “a lot of their historical records aren’t around; they were destroyed”) and did use traditional Aztec instruments, he had a revelation that broke the whole project open. “I was born in Los Angeles,” he said, “but my parents are immigrants from Mexico.”

Aztec Death Whistle: Not Just A Great Band Name

“It was crazy to try to do this,” Plum said of the world of sound he created for Aztec Batman: Clash of Empires.

For the approach he labeled as “reverence combined with complete irreverence,” Plum took traditional Aztec instruments, combined them with the “grand Gothic sound that was created by, say, Danny Elfman in Batman ‘89 along with Shirley Walker in the Batman animated series,” and blended all of the above with “my own sort of spin on it.”

The score began more traditional, using clay flutes, cylindrical drums called teponaztlis, and the infamous Aztec death whistle. “[It’s] this horrific kind of banshee screech,” Plum said of the latter, adding, “apparently, when the Aztecs were marching into battle, there would be, like, a hundred of these playing at once in the dark.”

But, the composer specified, “Once I had [these instruments], I used them in my own ways.” This was especially the case upon the arrival of the movie’s primary villain.

“When Cortés arrives to the New World,” Plum shared, “he brings armor and gunpowder and things that never existed here. So when those first fights start happening in the film, I have electric guitars going into this primitive tribal drumming and then actual metal punk drums playing through it.”

Plum even enlisted a California-based band called Heavenly Trip to Hell for the “really hardcore metal stuff,” to take things to the next level. To the composer, it was about “bringing electricity” which, he clarified, “was not what they had, but symbolically, it kind of reflects what’s going on in the film.”

But no villain provided the kind of musical opportunity for Plum that Yoka did. “I’ve kind of, for better or for worse, pigeonholed myself as this cartoon guy,” the composer said. “This is the first time I’ve really just gone off the deep end and done something dark.”

“It’s a lot of harsh noise stuff,” Plum said of his dissonant music for Yoka, “which was sort of stepping outside of my own musical comfort zone … he’s a pretty intense villain, so that was a lot of fun.”

Batman’s Iconic Theme Just Barely Found Its Way To Mesoameria

There is a moment in Aztec Batman: Clash of Empires in which Ego Plum summons Danny Elfman’s beloved Batman theme. It was not a musical moment to be taken lightly, nor was it a musical moment that was always going to find its way into the film. “I had this idea early on,” Plum admitted, for one reason.

How it found its way into the film, though, is its own story.

“One time I was with him at his house, right after he did Justice League,” Plum shared, “and I said, ‘Hey, I noticed that you used John Williams’ Superman theme in the film. You could have easily written your own thing, but you used that. How did that come about?’”

Elfman’s response, the composer said, was simple: “He said, ‘Well, to me, that’s the only real Superman theme. Those notes that John Williams wrote are as important as the red тιԍнтs and the cape.’”

“I go, ‘So, did you ask him?’” Plum said, revealing that Elfman did in fact “ask [Williams] for his blessing.”

Flash-forward to Aztec Batman: Clash of Empires, and Plum found himself in a similar position. “I sent this long email to Danny explaining the vision,” he said, “hoping that he’d be receptive. I wrote this really long letter and he just wrote back one sentence: ‘Sounds great, do it.’”

But that wasn’t the only hurdle. “Warner Brothers technically owns that,” Plum said. “Somehow they had to do some legal stuff, even within their own company, to make it happen. It almost didn’t happen, which is kind of crazy … but it was great to have that little moment of those Danny notes.”

SPOILERS FOR THE ENDING OF AZTEC BATMAN: CLASH OF EMPIRES BELOW

How Aztec Batman’s Post-Credits Sets Up A Huge Villain Twist

One of Aztec Batman: Clash of Empires’ most exciting moments occurs after the credits start to roll. A new villain is introduced as the Penguin, masked and wearing robes that make him look like a cross between an ancient plague doctor and Darth Vader, waddles onto a beach in the New World.

The villain is accompanied by something new to the world of the film: organ music. “It’ll give away a little bit,” Plum said when asked about the cue, “but there’s a religious sort of quality to this character. Perhaps he’s like a priest.”

“With having an ᴀssociation of the church, with the grand organs, of course, that comes later in history, but there’s this nice religious quality to organ playing and organ melodies that I thought would be appropriate,” Plum said, “even though it is a bit anachronistic as far as time.”

The composer left it there, saying “we shouldn’t talk about that too much because that is what would happen next,” although he made ᴀssurances that “the director has tons of ideas and other potential characters, and has talked about a bunch of really cool ideas.”

Aztec Batman: Clash of Empires is streaming now on HBO Max.