Little Sisters (originally named as Gatherers) are young girls who have been genetically altered and mentally conditioned to reclaim ADAM from the corpses around Rapture. Little Sisters are almost always accompanied by a Big Daddy. They are almost completely immune to damage and have no offensive abilities. Attacking them, however, will incur the wrath of their protectors.
Dr. Suchong, realizing that the need for ADAM was greater than the amount produced by the Little Sisters themselves, pioneered a way for them to recycle ADAM from the blood of dead Splicers, greatly increasing their ADAM yield. Naturally, the children were unwilling to co-operate. Dr. Suchong was able to mentally condition the children to have a neurological impulse to feed and made them associate the bodies of dead Splicers as "Angels" to make the process more appealing for the girls. With a physical and neurological drive in place, the Little Sisters eagerly pursued harvesting ADAM in Rapture. Like many of the tools in Rapture, the Little Sisters' syringes were cobbled together out of whatever the makers could salvage: large needles, hose nozzles, and baby bottles.
To make them more effective in their operation, the Little Sisters were conditioned to see the world of Rapture very differently than the other inhabitants do. Instead of seeing the dark, deteriorated state of the city, they saw an idealized world, with rosy marble floors, pink drapings, and flowering vines growing everywhere. Little Sisters saw their Big Daddies as noble golden knights, and they saw Big Sisters as brides or princesses with elegant ballroom apparel. Statues appeared to them as Big Daddies, pools of blood as rose petals, random fires on the floor as fireplaces and the dead bodies of Splicers as "Angels"; sleeping men and women lying on the ground with the outline of a halo and angel wings surrounding them. Splicers themselves appeared as beautiful, elegantly dressed men and women in masquerade masks, conversing civilly, when in reality they were violently fighting. However, the little girls' world view would be brought abruptly back to the grim, twisted
"Hi! I'm Anna and I'm 6 years old atleast...I think my name is Anna. Sir Grey gave me that name. I have three protectors but I have a favorite. I was told a few days ago by Sir Grey that I should have a name. He gave me the name "Anna" after I listened to a tape recorder thingy that was left outside my vent after I was taken here to Rapture."
"There was a woman's voice from the tape recorder and Sir Grey was crying after the tape was done, I dont know why though. The recorder said this." Pulling out the tape recorder she pressed the play button on the side of it and a woman's voice was heard, she sounded sad and broken up. "I have been working with Mr. Ryan ever since I first took apprentenship in his lab. But I have never found such an outlandish demand when he wanted my daughter to become one of his gatherers."
"I would never want to put her through such harm. I loved her too much for this kind of thing to happen. I quit his lab after countless requests. It wasn't then when I came back home from the grocery store I found my house in a mess. Papers everywhere and blood on the walls. My husband lies dead on the ground with a bullet hole in his head. It's apparent that" the woman starts to break into tears "That..." she starts to cry a little harder "That b*****d RYAN TOOK HER! I just want Anna to know that I will find her one day and that she'll be safe."
She looked up from the recorder and blinked "Mr. Ryan gave this recorder to me, telling me I dont have a Mommy....But I do have a Daddy and he'll protect me forever. I dont know why he gave the recorder to me but he did. Mr Ryan treats me different than the other girl's that live here, telling me I can Gather MORE Adam than the others. That he looks a me....as a Daughter."
Anna doesnt know what she's capable of, when Drake T. Ownes (A.K.A. Sir Grey) first came to Rapture and injected the very first Plasmid into his arm, Anna protected him from the other LITTLE SISTERS from taking his life. Once Grey came to, she immediatly hugged onto his leg, a rouge Big Daddy saw this, getting angry Anna tried to tell him to leave Grey alone. The Big Daddy didnt listen to the small girl and was about to finish him. Anna once again tried to confront him, the Big Daddy still didnt Listen to her and suddenly the Big Daddy caught on fire, his armor melting even. The rouge Big Daddy died in the process and Anna fell unconcious, when she woke up she had no memory of what she did. Grey confronted Tenebaum in attempt to explain that Anna can use plasmids due to the extra ADAM she is able to handle.