Dafoe was previously glimpsed in a photo with Aquaman and Mera as they were going over maps, but this newest photo puts him in the fight directly, as he is seen riding a shark that has been armored for use by the Atlantean military. Whether he's decided to accompany Aquaman and Mera or is doing what he can for the Atlantean army remains to be seen, as in the trailers Atlantis looks to be in some sort of civil war. If you're going to ride into battle, it doesn't really get cooler than a shark right?
You can check out the photo below.
Vulko has been an enemy and ally to Arthur at various times through his history in the comics, often disagreeing with Arthur on how Atlantis should be run. The character was actually supposed to show up first in Justice League, but that sequence ended up being cut out of the film. In the film Vulko will be a big part of Arthur's early years, informing his viewpoint on the throne and being there after the citizens of Atlantis kind of reject him.
"Vulko's his connection to Atlantis," Momoa told GameSpot. "I think what Zack [Snyder] and I did, we were kind of trying to establish that he was taken down there as a boy, and he was an outcast, he was a half-breed, and he was built up as a young boy, because he was fed all these ideas by Vulko--that he was the rightful king. And he gets down there, and he's a half breed, he's impure, and I'm just made to feel like I'm this disease. So after that, I was like, 'f*** you, f*** you, I'm on my own.'"
That's part of the reason Arthur is so at odds with Atlantis and the people who live there.
"He hates Atlanteans, he cannot stand being on land. He just--he's stuck in the tide. That's what Zack wanted," Momoa continued. "He was a blue collar worker. The guy worked in very lonely places, on oil rigs, he'd weld, and he could just be in peace, and he could exist on there and no one would know his secret. But there's things where ships went down and he couldn't save enough people, and he lost friends. The human side of him can't deal with this power that he doesn't know how to control yet."
Aquaman stars Jason Momoa (Arthur Curry/Aquaman), Amber Heard (Mera), Nicole Kidman (Queen Atlanna), Patrick Wilson (Orm/Ocean Master), Willem Dafoe (Nuidis Vulko), Yahya abdul-Mateen II (Black Manta), Temuera Morrison (Thomas Curry), Randall Park (Stephen Shin), Michael Beach (Jesse Kane), Ludi Lin (Murk), and Dolph Lundgren (King Nereus), and is directed by James Wan.
Aquaman sails into theaters December 21st.