Ancient Atlantean prophecies foretell that the kingdom shall ever be struggled over by two brothers. This struggle is currently fought by the Atlantean king, Aquaman, and his half-brother, Ocean Master. Orm is the son of Atlan, an Atlantean mage and father of Aquaman, and an Eskimo woman.
Learning of his origins from his mother while she was drunk combined with seeing a young Aquaman in love with the woman he wanted for his own drove Orm over the edge. He swore that he would not rest until he had destroyed all that brought joy to Aquaman. Years later, Orm arrived in Poseidonis where Aquaman sat on the throne, and presented himself as Ocean Master, the rightful ruler of Atlantis.