WARNING: The following contains spoilers for Aquaman, in theaters now.

While the internal struggle of Jason Momoa's Arthur Curry in Aquaman involves him reconciling the two parts of his heritage, the external conflict places him on a collision course with his younger half-brother, King Orm, who's determined to unite the undersea kingdoms behind Atlantis to wage war against the surface world.

As the machinations of Orm (Patrick Wilson) encounter obstacles, first in the arrival of Arthur, who also has a claim to the throne of Atlantis, and then in resistance from the kingdoms of the Fishermen and the Brine, he doesn't merely adopt the somewhat-sinister identity of Ocean Master. It's actually a formal title that holds deeper meaning.

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Introduced in 1966 in DC's Aquaman #29, Orm has feuded with Arthur over the decades for the Atlantean crown. Their rivalry inevitably boils down to Arthur having to stop his half-brother (or brother, depending upon the era) from flooding the surface out of pure hatred. But in all iterations, especially the New 52 comics that so heavily influences the film, one thing remains constant: Ocean Master is a moniker that Orm bestows on himself out of vanity, and to intimidate his opponents.

However, director James Wan and his collaborator transform Ocean Master into a mantle that one has to earn. It's the title granted to the person who unites a majority of the seven undersea kingdoms, which then gives him the authority to lead the combined armies in war against the surface. Already king of Atlantis, Orm tricks King Nereus (Dolph Lundgren) of Xebel into an alliance, and then brazenly assassinates the Fishermen King to force his heir to pledge her loyalty.

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With the Deserters Kingdom extinct, the Hidden Kingdom lost to the mists of time, and the Trench dismissed as little more than mindless monsters, that leaves only the Brine. Prematurely clad in the Ocean Master regalia, Orm leads the forces of Atlantis, Xebel and the Fishermen Kingdom against the warrior Brine in hopes of forcing them into submission, and securing his position as ruler of the seas.

But in the finale, the concept of the Ocean Master is redefined again when Arthur retrieves the sacred trident of King Atlan, the legendary ruler of Atlantis from before the Great Fall. Anyone who possesses the ancient weapon gains control over the ocean itself, and is recognized as the rightful ruler of Atlantis. What's more, he earns the title of King of the Seven Seas, the Ocean Master.

Aquaman

Arthur uses the trident to summon to his side the legendary monster Karathen, the Trench and virtually every sea creature for miles, and turns the tide, disrupting the attack against the Brine before meeting Orm in single combat. In his defeat of Orm, he wins over Xebel and the Fishermen Kingdom, as well as the army of Atlantis, not only securing the throne but earning recognition as the true Ocean Master.

Directed by James Wan, Aquaman stars Jason Momoa as Aquaman, Amber Heard as Mera, Patrick Wilson as Orm, 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.