EXCLUSIVE: Patrick Wilson has been set by Warner Bros and director James Wan to co-star in Aquaman. Jason Momoa plays the title character, and Wilson will play the fish whisperer’s supervillain half brother ORM, also known as Ocean Master, in the DC film that Warner Bros will release October 5, 2018.

The character has some of the sibling-rivalry elements found in Loki. That is Thor’s half brother, who has figured as the heavy in numerous Marvel films, in the form of Tom Hiddleston. ORM is at least as disagreeable and more powerful: In the comics, Aquaman’s human half brother is a rival for the throne of Atlantis and wreaks havoc on the high seas and beneath them when he doesn’t get his way. Amber Heard is playing Mera, Queen of Atlantis.

Wilson, who earlier this year starred in his second Conjuring film, opens Friday in The Hollow Point and plays the romantic rival to Michael Keaton’s Ray Kroc in the upcoming The Founder. CAA and Anonymous Content rep Wilson.

Aquaman first was seen in a cameo in Batman v Superman: Dawn of Justice and plays a major role in the Zack Snyder-directed follow-up Justice League, in which he and other DC Universe heroes face off against the  villain Steppenwolf.