Spoilers -The sick part of the Lil Sisters, it's when you get in the head of one. You get to understand why they're so careless and innocent... even though they stab dead people with a 1cm wide sirynge. They're basically brainwashed and hallucinate drapes and greek architecture and nice 50's people with bal masks, and toys. Very disturbing.
Yeah, I remember that part,It's funny because they still see the big daddies the same,But they see the big sisters as brides. It it pretty creepy, The idea kinda reminds me of Silent Hill. Because children don't experience the hell that it actually is.
Silent Hill is also a psychological mess. But since kids usually have much less remorse and regrets than adults have, it makes sense that they don't actually get influenced by the dark powers of the town. It's different from one game to the other, but the power is always about pain. Psychological and/or physical.
It's a good thing that children are spared the horrors of both Rapture and Silent Hill... though in Rapture they're still being abused. A child in all his mind wouldn't be able to last more than one day in the constant horror of Rapture, especially not if he has to stab dead peoples and be dragged around by a deepvoiced giant golem who kills people.