Nereus is the king of the underwater kingdom of Xebel and the father of Mera. He joined King Orm in his plan to unite the kingdoms of Atlantis during the War for Atlantis and also helped him try to take over the surface world. After Aquaman retrieved the Trident of Atlantis and defeated Orm, Nereus gave up the plan and the Kingdom of Xebel reunited with Atlantis after the war.
The Ruler of Xebel
King Nereus is the leader of Xebel, one of the 7 successor kingdoms of the original Atlantean Empire. Like his Atlantis counterpart, King Orm, he has a significant distaste of the surface world and its people. When Nereus goes to war, his daughter Mera was taken in by Queen Atlanna of Atlantis.
Reunion of Atlantis
During a clandestine meeting arranged by at the Council of Kings, Orm makes an impassioned speech of past glories and surface threats while Vulko offered him a chance to unite the Atlantean Empire. However, Nereus correctly deduces meeting's intentions by responding to Orm's request for an alliance to be a 'stillborn' proposition, theorizing that Xebel was the only kingdom able to give Orm the military support needed to force the Fishermen and Brine Kingdoms to fall in line. By obtaining or forcing the pledge of the four kingdoms, Nereus surmises that Orm will be declared "Ocean Master" and will command the greatest military force on the planet. This back and forth between Orm and Nereus eventually devolves into Nereus questioning Orm's claim to the throne of Atlantis where Orm angrily responds by dismissing his half-brother as loyal to the surface.
However, this discourse is violently ended when a commandeered Russian attack submarine-launched torpedoes at the Council of Kings. Taken by surprise, Nereus and Orm attempted to counterattack but were stunned by another exploding torpedo. Trapped under debris, Nereus was saved by Orm who then swam to the submarine and destroyed it. Finally convinced of the surface threat, Nereus pledged his forces to Orm's cause.
Nereus stopped Orm from killing the Brine King, believing that they can use him to secure an alliance with the Kingdom of the Brine, but the Brine King defies Orm and they are interrupted by the emergence of Karathen, Mera and Aquaman. When Mera informed him that Aquaman is the new king of Atlantis, he stopped fighting. After the war, the Kingdom of Xebel was among the many kingdoms that reunited with Atlantis. 
Like King Orm, he also had a distaste of the surface world and its inhabitants but unlike Orm, his view of them didn't reach amoral levels, as he showed reluctance to go to war against and eliminate all humans and was willing to either let them destroy themselves despite Orm's insistence of them first destroying the sea or finding a peaceful solution. He only agreed after the surface world attacked him. Despite her betrayal, Nereus loves his daughter Mera dearly and tried to convince her to join him, but Mera denied his offer and even then, Nereus still did his best to protect her from Orm, even threatening to stop cooperating with him if he dared to not return Mera to him safely and ordering his troops to not harm her when she came and despite once again trying to make her join him, was willing to consider her revelation of Arthur having acquired the Trident of Atlantis and thus is the worthy King, eventually displaying his reasonable side by accepting it upon Orm's defeat. He also cared about his kingdom, wanting the best for it and trying to make the right choices. King Nereus is also brave, willing to stand against the Kingdom of the Brine when he fought against them.
Powers and abilities
- Superhuman strength: As an Atlantean, Nereus has incredible superhuman strength.
- Superhuman durability: Nereus, as an Atlantean, is incredibly durable, as he is able to withstand immense underwater pressures.
- Superhuman speed: While underwater, Nereus can swim at supersonic speeds.
- Aquatic adaptation: Nereus can survive both underwater and on land.
- Aquatic respiration: As an Atlantean, Nereus is able to breathe underwater.
- Expert swimmer: Nereus, like all Atlanteans, is an extremely skilled swimmer.
Armor: He used armor to defend himself against his opponents and he uses it in battle.
- In the DC Comics universe, Nereus was not Mera's father but instead her ex-fiancée thanks to an arranged marriage. It was Mera's father, Ryus, who sent her on a mission to assassinate Aquaman and Mera instead fell in love with Arthur. Upon learning Mera's loyalties to Aquaman, Nereus tries to kill Mera.