From all appearances the history of Earth-9966 closely mirrored that of Earth-616 until the faithful day when Reed Richards and his friends tested out his newly built spacecraft. In this reality, the four people aboard were killed in the crash, thus the Fantastic Four never existed in this reality. As a result the Sub-Mariner remained an amnesmatic derelict for a while longer. His memories were restored when his fellow tenants at a New York flop-house injected him with morphine and dumped his body in the ocean. The water revived Namor's memories. He then recovered the Horn of Proteus and used it to summon a massive sea creature called Gargantus to attack the surface. Even without a Fantastic Four in this reality, Namor was eventually driven back.
Finding his people in Atlantis, Namor married his long time lover Lady Dorma and then began plotting to take over the surface world. Allying himself with his counsin Namora his daughter Namorita as well as Lemurian rulers Llyra and Karthon as well as the barbarian Attuma, Namor was able to accomplish this goal. Addressing the United Nations he told them surface dwellers that they could live their lives as long as they respected the will of New Atlantis. Namor then set up a new palace in New York City.