This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / BioShock 2
"Big Sister doesn't want you playing with me..."
The fact you're called SubjectDELTA implies that, even with all the screwed up stuff you learn about your past, there were 3 more before you.
In one of Alexander's Audio Diaries, they mention that they were currently testing Subject Sigma. Its implied that Delta may be the only one with sanity and considering later events, it is implied that Alpha Series Big Daddies are still being made. Makes it something of a relief that you actually get to play Sigma, huh?
Actually, they stopped production on Alpha Series (with Delta and Sigma being the only sane ones)... well, Sofia Lamb actually had one more Alpha Series produced, which acts as the final boss of the game: Augustus Sinclair.
Then you see Ryan's own animatron at the very end of the park. Only, by now, it's seen much better days when it still looked at least human.
"This is not your daughter. Her name is Eleanor, and she is mine." There is no love in this voice. No affection. Merely possessiveness. Lamb sees Eleanor solely as something belonging to her, to mold and shape as she sees fit. And then she tells you to remove your helmet, put a pistol to your temple...
With a plasmid that you probably have used in the previous game.
And that you'll probably use in this game still. Hypnotize Level 3.
Don't think of it in terms of Big Daddy/Little Sister. Think of it as a father watching his daughter watch him commit forced suicide.
The fact that Lamb used her psychiatry sessions not to comfort vulnerable and needy people, but rather to Mind Rape them into believing they were horribly selfish, "cure" them of their "selfishness", and get them to join her creepy Utopian cult is utterly evil, and utterly terrifying. More than one diary talks about how the speaker was so awful before Doctor Lamb "cured" them, but now they can serve the Family and do some good...
The fact that she is just waiting next to Eleanor when Delta finds her in Persephone, prepared to smother her own daughter just to stop him. This pretty much drives home the fact that she doesn't see Eleanor as a daughter; as something to care for as a person. She sees her a tool to be used as she sees fit and for nothing more and no-one else, and is fully prepared to nearly kill her if it means she's denying her to someone else.
Her line right before is enough to make your heart sink.
Her demeanor, which seems so cold and detached in comparison to Ryan. He at least showed passion in keeping "his" city, whenever he communicates with Jack. Sofia just seems cold and uncaring, speaking to Delta like he's just some especially troublesome organism on a lab table that won't stay still.
After Eleanor and Delta begin their escape, Sofia chimes in with this. She's gone off the deep end. And she intends to drag everyone down with her.
Sophia: Subject Delta ... I know you can hear me. You have stolen my life's work, and with it — my only daughter. But Rapture is the house of monsters. The surface will not have us. And now, we shall be buried as a family. Side by side.
Even creepier is one later on, where she reaches out to Eleanor in a vain attempt to change her mind. And she ends it with "Mummy loves you."
Early in the game the player comes across a photo reading "Rapture's best and brightest 1952". Who's on it? Tenenbaum, Cohen, Alexander, Ryan, Lamb, and Suchong. Tenenbaum looking nervous and childlike, Cohen looking oddly warped, Alexander distant and unfocused, Ryan glaring at the camera, Lamb smiling calmly, and Suchong utterly indifferent. In other words it perfectly captures everything that makes each character scary. Talk about a picture being worth a thousand words.
The Baby Jane splicers are big on the above, mixed with Tearjerker when you realize she was an actress forced into prostitution, veering around to Fridge Horror (in light of the prostitution) when you've got a Little Sister with you.
"Why would you bring a kid?!"
Whenever her delusions about audiences and gofers weren't making you laugh, they were extremely unnerving. Granted, this is while the splicer is attacking you, but that doesn't make whatever they're reliving any better.
"You sick bastard!"
"I've got my limits!"
"You're hurting me!"
"This wasn't part of the deal!"
"Get away or I'll scream!"
"Help! He's in my room!"
"Call me a whore? How dare you!? I'm an actress! I... I am..."
The Big Sister. No matter how many times they signal their presence with that high pitched scream, it never loses its effectiveness. You'll still be madly scrambling about, trying to set up a perimeter for their imminent arrival.
It doesn't help that you can often look out the windows and see them swimming around, seemingly stalking you.
It's even worse than that. Later in the game we found out that while her sanity might've been impacted, Lamb's Utopian project wouldn't change Eleanor physically, because Little Sisters are immune to the negative effects of splicing. That means that under the armored shell of every needle-bearing assassin sent to make you pay, there's a perfectly normal-looking teenage girl who has been driven mad by the programming they were under for most of their childhood, and kept under Lamb's control by another round of programming before being put in her suit, and forced to do Lamb's bidding. And you can't save them. They're too far gone. You can only frantically riddle them with bullets with the knowledge that it's you or her.
... and wonder if underneath it all she's aware that Mr Bubbles is the one trying to kill her.
The fact that, according to a conversation between Elizabeth and Dewitt/Comstock in Burial at Sea: Episode-1, many of these girls were at one point pimped out by Sander Cohen when they were younger.
There's Ryan Amusements, an Objectivist-themed amusement park meant to "educate" kids about the dangers of the outside world. Even Andrew Ryan himself thinks the Nightmare Fuel is overdone, noting the Uncanny Valley quality of the figurines. There are giant hands that would be sitting around, ready to represent whatever Ryan didn't like. Ryan animatronics that you can whack the head and arms off and the torsos continue to twitch around. The last one is mangled and strung up hanging from the ceiling.
It's sickening once all the farmer's limbs are taken off, and once the animatronic starts, the farmer's headless, limbless body is just... jerking around.
Perhaps most disturbing is the audio diaries. Apparently, once the populace started to revolt against Ryan, he had many parts of Rapture quartered off, one place being the park. You come across a series of audio diaries from a chaperone leading a field trip when the park was closed off. You get to follow along as she and all the students slowly die of starvation.
Although, it's implied that (some of) the children did survive, as the chaperone and some other adults gave them all their food. What happened to the children afterwards, though, is probably not worth speculating on...
Siren Alley. The brothel area has its multitude of dead hookers pinned to the walls and ceiling with speargun ammo.
The end of the level when the place starts to flood and Lamb chimes in to add another layer of creepy to things.
"Subject Delta, I want you to commit this moment to memory for me - this howling, brutish slog through the dark. This is who we are. Look, Delta, this is the world for which you strive. You... alone... among the dead."
In a certain area of the game where you're told, specifically, EVERYONE DIED OF DROWNING, you come across a disjointed audio log from a shy little boy who has a crush on a Little Sister. It's heavily implied he was killed by her Big Daddy, or drowned when the place flooded.
It's even worse because, before Fridge Horror sets in, that's about the happiest audio diaries you come across.
Add to that that another audio diary from the boy's mother (and yet another one on the website) reveal her husband and the boy's father was taken away by Ryan. You discover the fate of the father in a diary in the cells of Inner Persephone. He... escaped.
At one point, you can find a 'Present to the yellow-eyed girl', presumably from the above boy. It contains a single rose. Tear Jerker indeed.
Cohen's Collection. Listen carefully when you start up the gathering event in the area. You can hear Cohen laughing...
Gil Alexander's fate.
When confronted with that... thing, you have the option of either fulfilling the person it used to be's final request for euthanasia, or letting it live, after it promises to "go outside." Now imagine that◊ swimming around in the cold, lightless depths of the Atlantic...
It's worse, from a psychological aspect, when you actually have no idea which is the 'good' option. Then you either walk out of there and live with the guilt of having let that thing continue it's reign of terror, or you kill him... and get that image burned into your mind for awhile. If you let him live, later on when you go through the eyes of a Little Sister, you'll find a statue of Delta pulling a man out of a sea-monster's mouth.
Worse is imagining that swimming around in the very brightly illuminated depths near Persephone. Whatever is at the bottom of that trench, it's been hinted to be the ultimate source of ADAM. Gil can't avoid seeking the stuff, as revealed by the plants attracting him to the front of his tank even when he knew that they could kill him. Imagine what might happen if he found his way down to the bottom of the trench and gorged himself for decades on more ADAM than he could possibly consume.
The fate of Mark Meltzer, who went to Rapture looking for his daughter Cindy who was kidnapped and turned into a Little Sister, and he wound up being turned into a Big Daddy so he could be with her. Then you wind up killing him near the end of the game, but you can still save Cindy.
Seeing Rapture through the eyes of a Little Sister. The fact that everything is beautiful and sunny, with rose petals across the ground and butterflies floating around only makes it THAT. MUCH. WORSE.
Especially when you get short flashes of how it actually looks.
The rose petals are blood stains on the floor. Also, all the walls and ceilings seem to be covered in the same stuff as a padded cell.
Really doesn't help that you get to listen to the echoes of creepy laughter every few seconds if you decide to hang around long enough to harvest ADAM and collect items.
When you get close to the windows as a little sister you can see the glass isn't smudged or cracked like normal, but rather spotted... with tiny, childlike handprints.
Or that they see the Big Sister armor as Tiara (the helmet), pretty dress (the suit) and silk glove (the weapons). When I grow up I wanna be a princess!
The little sisters always see this...every second, a perfect world where no one gets hurt and nothing is scary. This is due to the conditioning they went through. When you rescue a little sister, you remove this perfect dream world, throwing them permanently into a world of sheer horror, death and destruction. When you don't, the little sister's see nothing but their daddy there, ripping out the very thing keeping them alive. Their last thing they see is the one they trust most of all murdering them, most likely staying in their perfect little dream world.
Somewhat mitigated by the fact that, after playing the first game, it seems likely that the programming persists after the Little Sisters are rescued (the ones that you escort around still find your appearance as a Big Daddy beautiful, and apparently still want to harvest corpses, despite no longer having their ADAM slug). This, of course, brings up a lot of questions about what life would be like on the surface for the ones that you have the option of rescuing. Coupled with the fact that their programming starts to decay as they get older and that it can lead to insanity if it's not been deliberately broken, this gives a new dimension to the good endings to both games. Even after leaving Rapture, the Sisters aren't out of the woods yet. However, the ending of the first game shows the little sisters growing up. They seem to adjust to it just fine.
According to Gil Alexander's audio diaries, when the original Little Sisters grew up, their programming started to decay, and they became feral and insanely aggressive: in other words, picture the first option mentioned in the entry above... and inflict it on a teenager who has spent years happily wandering her own dreamworld, and by now has enough ADAM-induced superpowers to be extremely dangerous. After suddenly experiencing the real world after a decade of comfortable hallucinations and learning that everything there is trying to kill you, going insane is horrifyingly understandable.
When you find the Big Sister suit and reality intrudes, you can hear drilling and someone screaming. For all we know, that might be Sinclair!
One particular moment of Fridge Horror is, while making your way towards the first little sister ward, you can come across a room with a dead Baby Jane splicer propped up in a chair, facing the corner. If that's not creepy enough, the walls facing her have been clawed black.
Hell, even the loading music for Inner Persephone is unsettling. Appropriately it is an old Artie Shaw song called "Nightmare."
Even if you've been a paragon of virtue, Eleanor is still terrifying. She's every bit as aggressive as any other Big Sister, and, in between slicing up legions of splicers, can be heard to shout things like "This one died alone and afraid! Stand in our way and you'll get the same!"
Just think: not only was Sofia prepared to smother her daughter, she was standing there, waiting to do it. And she waited until Delta was there and would have to watch.
The Little Sister Training Facility is pretty unsettling in its own right, once you find out how the little sisters are trained. There are two buttons on a wall in that area. One of them is labeled with a picture of a Big Daddy, and the other with a picture of a normal person. Pressing the first gives you a free bag of chips, the latter shocks you. This is the EXACT same method that is used to train lab rats. These little girls are LAB RATS, nothing more. It's as chilling as it is tragic.
Using a fully-upgraded Hypnotize on Sinclair in his Big Daddy form. He brokenly pleads for death while fighting the mind control. Listening to him beg in that horribly strained and desperate voice is horrifying. Having to hear anyone do that...
The Spider Splicers. Dear mother of God and all her wacky nephews, the frigging Spider Splicers.
Especially the one in the movie theater area of Dionysus Park. You find yourself in a totally abandoned toilet block. No splicers anywhere to be seen, full of food and health packs...and one gene tonic. By now, you're pretty certain that nothing is coming for you, so you take the tonic, and nothing happens... Until you're halfway out of there, and a Spider Splicer just DROPS on you.
Just looking at what happened to the Crawlers is horrifying; they're barely human anymore with their elongated heads and arms, their huge feet with just 4 big toes, and their constant misery of hearing voices in their heads and killing people to get them to stop. Using Hynotize 3 on them implies that they get hypnotized by Lamb and what they say is a little heart breaking.
Doesn't help that the statues look like more of Cohen's work, or that, if you listen carefully, you can hear what sounds like someone taking a picture of you when you take the gene tonic.
Just hear it? If you turn around after grabbing the tonic, the camera flashes in your face before you immediately teleport back... Urgh. And the ambient sounds in that room are ever so creepy. What sounds like wind and gentle breathing...
The inner thoughts of splicers, still trying to convince themselves life is normal or that Lamb will cure them. Or the fact they might actually know what has happened to them.
What happens if you harvest a Little Sister instead of rescuing her: the little sister will squirm in your arms, crying and begging you not to hurt her. Then, the screen goes black...and you're holding the poor girl's slug which had been implanted in her stomach. The worst part is that the Little Sister simply doesn't know why her supposed protector betrays her. Tearjerker indeed.
Everything that terrified you and made you feel sorry for the Little Sisters gets so much worse in this game when you remember one simple fact: these Little Sisters are girls who were kidnapped from the surface.
There is also an uncomfortable element of Fridge Horror to this, as well. When you consider just how broken the Little Sisters are as a result of their "conditioning" (which really seems more like torturing and drugging them to the point of delirium), there's a serious question about how or if their parents are going to be able to care for them. Their behavior is likely to be uncontrollable and dangerous to at least themselves, if not others around them as well. The seven main Sisters from the first game are at least apparently okay, but that outcome is probably not going to be universal. There's a good chance that some of the Little Sisters will end up temporarily or even permanently institutionalized if their conditioning is hard to break.
If you harvest Little Sisters, whenever you adopt one, she'll say things like "Daddy...? You're never gonna hurt me, right?", "Daddy's home! I've been good! Promise!", "Daddy isn't angry, is he?", "I'll be extra quiet! I won't make you upset!", and "Where are we going? Daddy?" They used to see you as a knight in shining armor. What do they see you as here?
Seeing the picture◊ and the Model◊ of Gilbert Alexander...one for the Uncanny Valley feel of it, the other because it's a demonic fetus...Thing...
While the passive state of the Insect Swarm plasmid is less horrifying in this game (honeycombs on your glove, instead of having to watch bees crawl through your flesh), the effects have been appropriately ramped up. Now you get a swarm of angry bees with a smarter, more aggressive AI actively seeking out targets across several rooms. When they're not burrowing into corpses to lie in wait for the next hapless Splicer to come into range, that is...
"Daddy, Big Sister doesn't want you playing with me..." OHGODSHE'SONMYHEADGETHEROFFGETHEROFFGETHEROFF!
Eleanor in the Bad Ending. You just let a complete psychopath, packed full of ADAM and incredibly powerful Plasmids, loose on the world. And now that Delta is dead, the only things important to her are her "survival and joy". And by joy, she means ripping people apart. Now, think back on how easily she dealt with Splicers, who were no slouches themselves. You do the math.
Eleanor's completely psychotic grin in the ending is positively terrifying.
If using Incinerate at any time while you have a Little Sister on your shoulders, she may cheerfully chant "Marshmallows!" Though it's slightly funny, it's also slightly disturbing, as the process that turned her into a Little Sister possibly resulted in the girl finding humor in someone burning alive.
Though remember, the Little Sisters don't see the world in the same way we do. Chances are, the people you burned don't look like people to them anymore. It's your call as to whether that's more or less morbid.
In Persephone, if you search hard enough, you can encounter some prisoners. Not splicers, but just normal people. They don't acknowledge the player in any way, and just cycle through a crying animation until they are killed. Your HUD doesn't register them, unlike everything else in the game, meaning you could try meleeing one to get a reaction, only for it to crumple up dead. They don't even drop anything. Such a minor detail, yet chilling nonetheless.
How about the Little Sisters Orphanage in Siren Alley? When you go in, you find a few bodies about you can search, including a spider splicer pinned to the wall by a spear (and keep in mind, those are a new enemy at this point, so you're not quite used to seeing those freaks yet). On the way up, you catch a glimpse of a live spider splicer as he darts around a corner, but other than that, no real fights. But then you reach the end and get your loot and the power goes out, leaving your flashlight your only illumination. As you charge back the way you came, by that beam you keep catching glimpses of the spider splicer darting around corners one step ahead of you until eventually they trap you in the second floor hall. The following standup fight with the spiders and a brute is outright catharsis at that point! Oh, but on the way out shine your flashlight at the "dead" spider pinned to the wall: he's about to leap at you
The look on Eleanor's face when Lamb forces Delta to shoot himself brings up a tragic and disturbing thought. Little Sisters are conditioned to view the world as an idyllic paradise. They see corpses as angels, blood as roses, splicers as elegantly dressed men and women, and Big Daddies as knights in golden armor. So what was she seeing that made her recoil like that?
The physical appearance of Splicers in general is much more disturbing than in the first game. Their faces look half-melted, like something you would see with a serious burn victim who survived and the flesh healed as much as it could. They look like portions of their flesh have become swollen and detached from where they should be, and now are hanging down and bulging out with skin stretched over to contain it. And most of them do not wear masks now. Lovely.