When Mera returned to Xebel, Nereus assumed she’d gotten the job done and was ready to become his queen, but he was sorely disappointed.
King Nereus was introduced in Geoff Johns’ New 52 Aquaman run as the ruler of Xebel, an extra-dimensional underwater penal colony populated by Atlantean separatists and criminals.
Like Mera and the other denizens of Xebel, Nereus is able to control water and manipulate it into many forms, and that’s on top of the standard super strength and underwater breathing that every natural underwater dweller in the DC universe has.
Years ago, Nereus sent Mera to infiltrate the Atlantean kingdom to seduce Aquaman and get close enough to him so she could kill him, but Mera ended up actually following in love with the superhero.