With BioShock 4 presumably still in development, and no other news available on the highly anticipated sequel, fans continue to revisit the original games. One aspect of the first BioShock and BioShock 2 that made them so popular was the inclusion of the Little Sisters and the story behind them.
Little Sisters are young girls that were abducted from all around Rapture and mentally conditioned to harvest ADAM, a chemical substance that can rewrite genetics and results in special abilities.
Read more on gamerant.com