While speaking with The Hollywood Reporter, the filmmaker explaned the inspiration the inspiration for the decision came originated with director Mike Mendez, who was working with Lundgren on 2016's Don't Kill It.
"When I was in the process of writing this character in the world of Aquaman, a friend of mine, Mike Mendez, was working with him on one of his films, and Mike was just raving about how great Dolph was," Wan recalled. "And I thought 'Oh, my God, Dolph would be great for this role as well!' So it kinda came about from that roundabout way."
Aquaman is one of the highest-profile projects in recent years for Lundgren, the 1980s and '90s action-movie fixture who experienced a career resurgence with the Expendables franchise. "He's a really strong actor," Wan continued. "I don't think anyone gives him enough credit for how serious he actually takes his craft. He's taking it very seriously on this film."
Introduced in 2013 by writer Geoff Johns and artist Paul Pelletier in DC Comics' Aquaman #13, Nereus is the king of Xebel, a mostly forgotten extradimensional penal colony for an ancient group of separatists banished by Atlantis behind a sealed portal. Mera was initially promised to him as a wife before she fell in love with Aquaman and opted to betray her people and become his queen instead.
A recent photo leaked from the set of Wan's Aquaman showed Mera fleeing from what appears to be Atlantean soldiers, which suggests the tension between the two factions, and perhaps a love triangle, will factor into the film's story.
Arriving Dec. 21, 2018, Aquaman stars Jason Momoa as Aquaman/Arthur Curry, Willem Dafoe as Nuidis Vulko, Amber Heard as Mera, Patrick Wilson as Ocean Master, Yahya Abdul-Mateen II as Black Manta, Temuera Morrison as Thomas Curry, Dolph Lundgren as Nereus, Nicole Kidman as Atlanna, Ludi Lin as Murk, and Michael Beach as Jesse Kane.