| abilities = Fen could extract oxygen from the water through her gills and her body was able to withstand the extreme pressures and temperatures of the oceans depths. Her vision was exceptional in the murky sea. Like most Atlanteans Fen could not breathe above the water for extended periods without the assistance of chemicals, magic potions or spells.

bio_text= In early 1920, the ship "Oracle" arrived in the Antarctica, its ice-breaking explosions accidentally damaged the undersea city of [[Atlantis]]. Emperor [[Thakorr]] ordered a surveillance expedition, although, his adventurous daughter Fen took it upon herself to undergo the task of spy. She was encouraged by [[Atlanteans|Atlantean]] scientist [[Tulem]], whose operatives had prompted an interest in the surface men during Fen's younger years. Fen was given an experimental potion that allowed her to breath above water, it is unclear if she was aware that centuries of selective eugenics, overseen by Tulem and others, made her uniquely suited for procreating with humans. Fen met ship captain [[McKenzie, Leonard|Leonard McKenzie]], whom Tulem's forces had manipulated via telepath, [[Destiny (Paul Destine)|Paul Destine]], causing the couple to fall in love and they rapidly married. Atlantean soldiers drove the Oracle and its crew from Antarctica, and later that year Fen gave birth to [[Sub-Mariner|Namor]].