Irrational Games hit a home run out of the park with the original BioShock. It was a masterpiece plain and simple. One part of the game that really helped make it what it was came in the form of the Little Sisters and Big Daddies. Well, the Little Sisters weren't always so morally ambiguous... or even human.
The tweet above shows a glimpse through a gif of some of the concepts that the developers came up with while working on BioShock. As you can see, some of the concepts for the Little Sisters included maimed dogs with frail bodies scavenging for ADAM. Another sketch shows a frog with a device strapped onto its butt.
However, on the 2K Games blog they explain that the original concepts didn't work because the "Gatherers" (as they were known before being called Little Sisters) couldn't be empathized with. People weren't going to try to spare the lives of things that didn't seem to have emotions.
One of the core tenets of BioShock is its morality factor; a scale that hinges on the gamer's ability to question the value of artificial life: is this life worth killing to get stronger for? Can the game be won if this "Gatherer" is allowed to live? Etc., etc.
The developers wanted players to feel something when it came time to either kill the "Gatherers" or let them live... and a slug, robot or inanimate object was not going to draw any empathy from the player.
They put out a studio-wide call for concept art to come up with something new. They received all manner of different art, but the one that stuck out the most (aside from the frail dog in the wheelchair) was a little girl with an old woman's face.
Senior concept artist Robb Waters explained in the blog post...
The cute to spooky ratio was eventually balanced out and we ended up with the dirty pair of Little Sisters and Big Daddies. According to Waters, the Little Sisters in BioShock is what led to their protectors being the Big Daddies. It's now an inseparable pair of villains that have really marked their territory in the world of video games. The really cool part about it is that it's a lot more complex than simply being "good" versus "evil". We learn throughout the first game that there are plenty shades of gray.
BioShock 2 and BioShock: Infinite never quite managed to capture the same level of appeal with its villains the way the original game did with the introduction of the Big Daddy and Little Sister, but there're no worries because gamers can relive and rekindle the horrors, joys, and violence of Rapture and Columbia all over again with the remastered BioShock trilogy due for release on September 13th.