Nikkor

Nikkor is a traitorous friend of Mera and an enemy to Aquaman. He is a native of Dimension Aqua. 
 
Mera had lost most of her powers and discovered the downside of being married. Aquaman would frequently leave her behind to go on adventures. Meanwhile she was surrounded by the Atlanteans, who were rather cold towards their foreign-born queen. Feeling bored and lonely, Mera is glad to receive word from her dimension. Professor Xeron/ Kreon (inconsistent name) had managed to repair the dimensional warp ... with one little problem. People and things could come from Aqua to Earth. But could not return. Mera asked for a pet and a few friends she had left behind. 
 
Nikkor was among said friends who were send to Earth. Mera was unaware that the man had wanted to be her lover, not her friend. He soon had her drugged to both forget Arthur and act under his suggestions. Before long Mera was seen in public with her new lover and surrounded by foreign court favorites. Add a number of unpopular decisions, like tearing down the statues of former queens, the Atlanteans were openly threatening revolt. Nikkor took to abducting the most rebellious citizens and selling them as slaves to Taggert, a surface-world circus owner.    
 
An attempt by Aquaman and Aqualad to return and take charge of the situation only added them to Taggert's performers. While Aquaman was trying to escape, the Atlanteans openly revolted against the Mera-Nikkor regime. Both were captured and put on trial as traitors. They were sentenced to death by throwing them to the Dungeon Depths, bottomless pits  "from which nothing ever emerges". Aquaman returned just in time to learn where his wife was. He quickly followed her into the Depths.  
 
Nikkor and Arthur encounter each other for the first time. Nikkor admitted to having drugged Mera and started a fight with his rival. But then the trio were attacked by a monster of the Depths, one of the reasons nothing left the area. The two men joined forces against it while Mera stood by. Then Xeron/Kreon contacted her again. He found a way to retrieve individuals back to Dimension Aqua. But Mera refused to leave if it meant leaving Aquaman to die. Nikkor similarly would not leave if it meant leaving Mera to die.  
 
By the end, Nikkor distracted the monster long enough to let the other two escape. The usurper died a hero. Mera supposedly resolved to not get bored again. 
  
The story is considered poor for a number of reasons. Aquaman's take on ruling Atlantis seems to consist of being almost constantly absent. Aqualad spends most of the story trying to locate his mentor and update him on major events. Mera had previously been depicted with an impressive power set. Her loss of powers was supposed to prevent using said powers as a deus-ex-machina ending to all threats. But this was the second issue in a row where the depowered Mera is acting as a consort and puppet to a usurper. Nikkor is essentially a watered-down version of Oceanus, demonstrating none of the powers natives of Dimension Aqua possessed.

 Nikkor presumably shared several powers with Mera and other members of their race. Their world is covered entirely in water and their race are amphibians. Swimming is their equivalent to walking. Their main power is hydrokinesis. They have the ability to psionically increase the density of volumes of water and shaping them to create hard-water constructs. He can use them to cause blunt force damage or simply drown opponents. He has low-level telepathic powers, allowing him to communicate with others. He can not perceive the thoughts of individuals not broadcasting to him. His main weakness is common to all his race. Lead causes them to loose their hydrokinetic powers for the duration of their exposure to it