Bioshock 2 main caracter

Subject Delta (Symbol: Δ) is the protagonist of Bioshock. Delta was the first successful Big Daddy subject bonded to a Little sister. He has a Delta symbol on his suit. Delta is the fourth letter in the Greek alphabet, signifying that Delta was the fourth test subject taken from Presephone for Alpha series conversion at Fontaine Futuristics. Delta is also a symbol commonly used in mathematics to represent change or variation. 



 
Eleanor Lamb is the daughter of Sofia Lamb, and is a previous Little Sister. Roughly ten years after the 1958 New Year's Eve Riots she contacts Subject Delta, beginning the events of BioShock 2. Eleanor still remembers Delta after ten years and knows he is searching for her. Throughout the course of the game, she will leave him gifts and messages written on the walls of the city. In the story of BioShock 2, her behavior is highly influenced by Delta's actions towards the Little Sisters and NPCs. 

 Augustus Sinclair was one of the key figures in Rapture's science community as well as a prominent businessman. His business, Sinclair Solutions, was one of the most important Plasmid-researching companies in Rapture, and he is a significant character in BioShock 2, guiding Subject Delta to Eleanor Lamb. 

Dr. Sofia Lamb M.D, Ph.D, is a clinical psychiatrist and the primary antagonist of BioShock 2. She has taken over Andrew Ryan's position as the leader of Rapture, albeit with a completely different ideological view.