Augustus Sinclair was born in Panama in the year 1914. After his grandfather drowned, he moved to the United States in hopes of striking it rich. When Rapture was created, he took the plunge to the bottom of the ocean with the sole purpose of making money. He was a key player in the development of the Vita Chamber and was a well known business man, establishing Sinclair Solutions, a premier provider of Plasmids and Tonics. As a key player in both the rise and fall of Rapture, Sinclair is keenly aware of the background and motives of essentially every character, friend or foe, seen in the games.
Throughout the game, Sinclair helps Subject Delta by giving him objectives and telling him more about the current situation. In the last level of the game, Sinclair is captured and put in a Big Daddy suit. Sophia Lamb then gains control of his mind, preventing him from helping the player further. Sinclair recognizes that his mind is being controlled, but is unable to do anything about it. He acknowledges that Subject Delta must kill him to get a pass code in order to proceed further in the level, which the player does.
BioShock 2 Multiplayer
As the multiplayer feature is set during the height of Rapture in the 1950s, Sinclair Solutions is responsible for the competitions of ADAM-crazed Splicers that the players will control. Sinclair uses these battles to research and develop various plasmids and tonics, recruiting Rapture's citizens with the promise of power and gifts of precious ADAM. As a businessman, Sinclair did not take an ideological side in the process, letting Ryan and Atlas provide suitable motivation and fodder for the competitions.