Although the upcoming Warner Bros. film is titled Aquaman, director James Wan thinks the real star of the movie may be Mera, played by Amber Heard.

“Amber and I would always joke that the movie should be called The Adventures of Mera with Her Sidekick Aquaman," the filmmaker told The Hollywood Reporter. “She has way more superpowers.” Following her introduction in the film, Mera appears in virtually every scene.

RELATED: Warner Bros. Is Already Talking About An Aquaman Sequel

However, star Jason Momoa, who's known for his laid-back and mischievous behavior on set, resorted to a prank to ensure none of that went to Heard's head.

"She stepped away, and I ripped out the last 10 pages of her 800-page book, like the last chapter," Momoa told the outlet, which notes the book was Yuval Noah Harari's Homo Deus: A Brief History of Tomorrow, which is actually 464 pages.

RELATED: Aquaman: Amazon Adds Another 100 Theaters to Early Screenings

Directed by James Wan, Aquaman stars Jason Momoa as Aquaman, Amber Heard as Mera, Patrick Wilson as Ocean Master, Willem Dafoe as Nuidis Vulko, Yahya Abdul-Mateen II as Black Manta, Temuera Morrison as Thomas Curry, Dolph Lundgren as Nereus and Nicole Kidman as Queen Atlanna. The film opens on Dec. 21.