Eren's mother, Carla. Watching her son and adopted daughter desperately trying to save her when she's trapped under the remains of their house, legs crushed and unable to run. Then, having to force them to flee with them, only to regret it in the fearful realization that she is about to die. She wants them to come back.And Carla then covers her mouth, so she won't say it openly before kicking it. How Eren must have felt; watching poor Carla die right in front of him because he didn't have the strength to help her, and realizing the last thing he did before all this was have a huge fight with her...
The soldiers spend all their time boozing because the Wall protects everyone and they're convinced they can handle things if the Titans did come in, only for the emergency they've been trained for to occur and they realize they're not only unprepared, but scared out of their mind at the thought of dying.
Mikasa's backstory. She was enjoying a normal morning with her happy family, only for strange men to show up and kill her father, and intend to harm her and her mother. And it's all from her perspective. Then, almost the same thing happens again one year later with her adoptive mother (the aforementioned Carla) being eaten by a Titan and her adoptive father disappearing to parts unknown. So, in less than two years, she lost four parents and only has her adoptive brother Eren to desperately cling to now.
Deliberately invoked by Dot Pixis during the Battle of Trost where soldiers want to desert and spend their final moments with their loved ones. He told them they could leave, if they wanted their loved ones to experience the same kind of fear the Titans gave them. A father just about to leave imagines his beloved daughter screaming as a Titan picks her up. He and other would-be deserters return and go back into the fight.
Mizuka's death was pretty tragic, especially when you watch Kaito desperately doing everything in his power to try and save her.
Akiho and Misa. An older sibling has cut off ties from their family with no explanation and ignores any and all attempts at contact, and the last conversation they had with the younger was them calling her plain and saying she'd never accomplish anything. Then it's revealed she's being manipulated by someone else who is forcing her to cooperate by threatening the lives of everyone she cares about.
Code Geass has a couple notable ones. Lelouch and Cornelia are half-siblings from opposite sides of the conflict, with one thing in common: they both have full-blooded younger sisters, Nunnally and Euphemia, over who they would freak out if anything were to happen to them. In Lelouch's case this is VERY effectively invoked by Mao, who kidnaps Nunnally twice to catch his attention.
Kotoura-san: Haruka's backstory includes having her mother, who once tried to help her with her problems but ultimately couldn't cope with them, callously abandon her in front of her grandfather and saying she wished she never gave birth to her. And we learn that this is after Haruka's father utterly refused to help them either and then walked out on them! It's utterly heartbreaking.
Here's one courtesy of Death Note: What if a new serial killer arose, more prolific than any killer before him... and that killer turned out to be your son? Doubling up on the Adult Fear: On top of all of that, it's the parent's responsibility now to capture this serial killer so that he can be put to death. Poor Soichiro...
Taken on by the "What Do They Fear?" Episode of Full Metal Panic? Fumoffu. Since Sousuke grew up in a war zone, he's completely unfazed by the spooky atmosphere of the Abandoned Hospital, and dismisses ghostly apparitions and a blood-drenched Creepy Child as not threatening enough to worry about. What does shake his composure is the thought that Kaname, his charge, has been seriously injured or even killed after falling through the floor.
Grave of the Fireflies: Protagonist kids Seita and Setsuko are orphaned during wartime and have heart-wrenching difficulty in surviving afterwards, especially after they run away from their aunt who doesn't really care. Things like sucking on little stones and imagining they are food.
Bitter Virgin features the rarely brought up topic of miscarriage. It also features the life of a girl whose stepfather raped her while her mother was in complete denial when told about it (to the point of thinking her daughter was lying to cover up who she was sleeping with), until the poor girl got pregnant for the second time.
Brook. In a rare case of a main character who was middle-aged in his flashback, instead of the usual childhood traumas we got the story of a parent/authority figure losing friends and loved ones to tragedy and bad decisions, finally ending up old and alone.
Shanks, possibly the most easygoing character in the series, outright panics when Luffy is stolen out of his sight by a lowlife.
What happened to Boa Hancock and her sisters, Sandersonia and Marigold in their past. At a very young age, they were the junior members of a Kuja ship's crew... and once their older shipmates and caretakers simply took their eyes off the three pre-teen girls for mere minutes, they were kidnapped and then sold into slavery. It took them years to come back home... and they remain scarred, both physically and mentally, by the experience right up to the present day. Merely recalling the HELL they lived through can these three very badass women to tears. (And in Marigold's case, to a screaming Heroic BSOD)
Luffy, Ace, and Dragon turning into pirates despite trying to raise them as marines could be a parental failure fear for Garp. Even worse when Ace actually dies, and Garp has to ask Sengoku to pin him down so he won't go straight towards his killer to get revenge.
The Punk Hazard arc may have the worst case of this. Parents on the islands near Punk Hazard are told by a Mole in the Marines that their children suddenly died in accidents while they were out playing. In reality, they are being abducted for use in human experimentation which is poisoning them slowly to death.
Umineko no Naku Koro ni: Done in the fifth arc, with all of the Ushiromiya children except for Battler being killed off on the First Twilight. And then Battler in the sixth arc. Poor Rudolf.
Game X Rush: The deep backstories. Abandonment of a child, severe and prolonged physical abuse by foster parents, near-insane idolization of a psychotic "mother" who uses said child as an excuse to kill... And that's just one of the main characters. The other involves severe and prolonged domestic abuse, accidental arson, murder of one parent in front of the child's eyes.
Bokurano can be boiled down to Adult Fear. A young child is going to die and there is nothing their parent can do to stop it.
The Magical Girl Lyrical Nanoha StrikerS finale began with the simple yet real fear of losing your child because you were away when they needed you most - like it happened to Nanoha, Fate, and Vivio.
Genya Nakajima's elder daughter, Ginga, is kidnapped and his younger daughter Subaru gets hospitalized. In the third Sound Stage of the series, he approaches her and recommends that she withdraw from the case, emphasizing how hard it is on her, but is willing to accept her decision to continue. When you consider that his wife was killed in the line of duty, it's easy to see that he fears losing Subaru too. (Thank God Subaru manages to rescue Ginga, but still).
Hayate's plight in A's is another; she has been sick for a long time, and seemingly wonders if she'll die soon, but doesn't fear it because she's always been alone. And Graham believes that sealing her away with the Book of Darkness is regrettable, but in that case, few will miss her.
Kotetsu/Wild Tiger is a father in canon and therefore he really hates the mere idea of children being in any kind of danger. Worse still, in the second episode his daughter Kaede ends up in danger, and Tiger is not quite quick enough to rescue her. Fortunately, Barnaby saves her life in the nick of time.
Episode 15 brings a new Adult Fear for Kotetsu. Namely, the possibility of having a rare, progressive condition that will force him to give up what he loves most.
Ivan is a teenager, but he still has to face the fear of not having been able to help his friend when he needed him the most. Now said friend, Edward, is a supervillain.
Barnaby has to face a huge one later in the series: his parents' real murderer was... Maverick, his former Parental Substitute. So during a good part of his life, he has been raised by the guy who killed his mom and dad, and a good part of his whole identity is based onlies.
The moment where Maverick pats Kaede's head. The simple idea of what he could do to her gave the fanbase itself a major freak out.
All friends and colleagues suddenly forgetting who he is and then trying to terminate him for a crime he didn't commit is gutwrenching. It's one of the many reasons that Maverick is pure evil.
The way he lost his mother as a child left Ichigo unable to handle being powerless to protect those in danger. Villains often use this against him, culminating in one Arc Villain's mind-bending assault on his family leading Ichigo into an Heroic BSOD.
Having made two separate vows to always protect his dead wife's younger sister and always uphold the law, Byakuya's left dumbfounded when Rukia's execution brings the two vows into conflict. Although he's forced to support the execution, his worst fear is eventually confirmed to be Rukia dying, thus him being unable to hold up the promise made to his beloved and which involves the other person whom he cares for the most.
In Project ARMS, even though the ARMS teens are all actually raised by foster parents, they still are treated like the parents' own children. These parents then get to watch their children be attacked, nearly killed, and then get told "Hey, we have to leave for awhile and may not live, but we love you!"
The Chapel children. They were all the result of a group of women being given, without their knowledge, drugs that altered the development their unborn children. Not only that, but the parents are unable to properly care for their children because they're all afraid of them. Worse, though the children take on adult roles in the town they run, it becomes evident that the kids still need the love and support of their parents.
In Fairy Tail, it's revealed that Ur had been told by some researchers that her Ill Girl daughter Ultear had died, when in reality, they kidnapped and experimented on the girl, causing her to become one of the villains and to hate her mother Ur because she has been led to believe that Ur hated and abandoned her.
Jude Heartfilia may count as well. A few weeks after he reconciles with his estranged daughter, Lucy, and manages to get over the sudden death of his wife Layla, who Lucy is the spitting image of, she and her friends are attacked and seemingly killed. Even worse when Lucy returns and finds out that he's been sending her birthday presents every year since her disappearance... and then died a month before her return.
In Ashita no Nadja, Colette Preminger experiences a terrible dose of this when she wakes up from an illness-induced coma, only to be told by her retainers that her baby daughter Nadja had died of the same sickness that almost killed Colette herself. (Complete with a heartbreaking scene where Colette rushes to Nadja's wooden crib and finds it empty, collapsing in tears). In reality, Nadja had been sent away to an English orphanage to trick Colette into coming back home to her clan. And both mother and daughter only learn of the whole deal thirteen years later. (No wonder Colette gets pisse at her father, the one to blame for this, when she learns the whole truth).
Also, what if a person you care immensely for is mistakenly blamed for something you commited, is about to go to jail for it... and refuses to clear up his/her name to protect you? No wonder Keith almost snaps when Francis is willing to pull a Twin Switch when he's accused of the thefts Keith commited as a Gentleman Thief.
In the climax of My Neighbor Totoro, Mei has a fight with he sister Satsuki, and runs away to go to the hospital and give Mama the fresh produce from their garden herself. Mei is four. She does not know the way. She gets lost. Nobody knows where she is. Literally everybody in town goes out to search for her, fearing the worst.
One moment within the "searching for Mei" sequence stands out: The neighbors find a little girl's sandal in a pond, and show it to Satsuki. Nobody ever says it, but the obvious implication is they're afraid Mei drowned in the pond. It's not Mei's sandal, and she hasn't drowned.
In Rurouni Kenshin: Ishin Shishi e no Requiem, Yahiko runs away to join the rebels that were trying to overthrow the Meiji government, since his father died in a similar rebellion years ago.. Kaoru, having no idea where Yahiko had disappeared to, is frantic. When Yahiko is ultimately left behind by the rebels and comes back to the dojo, poor Kaoru greets him with a slap to the face and then proceeds to sob into him. Kenshin immediately tells Yahiko that, had Kaoru not slapped him, he would've done that himself.
The Jinchuu arc is a horrifyingly well-done attempt by Enishi to use this on Kenshin. So Kenshin wasn't able to protect his first wife Tomoe and the mere possibility of losing his girlfriend Kaoru terrifies him? Now Tomoe's vengeful brother deliberately exploits this fear to make Kenshin believe Kaoru has been bloodily murdered by him, thus making him revive these horrible memories. And Kenshin almost crosses the Despair Event Horizon after that.
The Psychological Horror implications of Saitou going to the Kamiya dojo behind Kenshin's back brings out the Adult Fear card with incredible strength. Think about it: he could've killed everyone there easily if he wanted to, and Kenshin wouldn't have been able to do anything. When Kenshin put two and two together, he almost had an Heroic BSOD.
Played horrifyingly straight in Anji Yukyuzan's backstory. The moment he left his old temple to meditate under a waterfall... it was the moment when he was beaten bloody by the local townspeople and said temple was burned to the ground. With Anji's adopted children inside. The terrible psychological consequences lead him to his Face-Heel Turn.
Chapter 501 and beyond of Naruto has Tobi threatening a newly born Naruto as an ultimatum to Minato and Kushina. After Tobi extracts the Kyubi from her, Kushina is left facing the reality that she will not live to see her son grow up. On top of that, her and Minato die knowing that they're dooming their child to a lifetime of suffering, unable to protect him from the fox, Tobi or the taunts of the villagers..
And later, we have this: Your eldest son, whom you love and raised/trained? He's commissioned with killing you and your spouse. And everyone else in your family. And when he comes for you, you clearly know it, as well as how said son is suffering for it. Your only option is to tell him "well, our deal suck, but go ahead and kill us if that's what you truly have to do. We love you no matter what".
And yet another example, pulled from a pre-Five Great Nations flashback: Back in the old days, the war meant that everyone fought. The series was already known for having Child Soldiers running around willy-nilly, but at least they're trained for combat and start out as civil servants/citizen soldiers—in the bad old days, this kind of thing amounted to seven-year-olds being declared shinobi, stuffed in armor and sent to the front lines. It's exemplified by how, when Hashirama Senju and Madara Uchiha's fathers met on the battlefield with their sons in tow, each adult's reaction was toimmediatelygo for the other's kids. Morality? What's that?
And lest we forget that Orochimaru has experimented on children before. Fifty-nine of which were newborn infants...
In Zombie Loan, minor character Sougiya is a single father trying to pay off his contract to the Z-Loan. He knows that if he isn't able to keep his end of the contract, he will die and then no one will be left to take care of his young daughter.
Puella Magi Madoka Magica. One girl has gone missing, another girl found dead, and their friend is very troubled by all that- but refuses any help from anyone. The mother of the latter is seen in the 11th episode, and doesn't cry because she tries to assure herself that the girl can probably handle the stress given enough time. Her mother must have felt powerless and desperate, seeing her once cheerful and gentle daughter grow so distant and detached.
Say, has your (insert: daughter, granddaughter, sister, niece, cousin, student, neighbor, friend, friend's sister, classmate, etc.) been acting distant or evasive? Coming and going at all hours? Maybe one day she'll simply never come home, and even if you call the police, no one will ever find her or any sign of what happened to her.
In the Cardcaptor Sakura anime, there's the episode in which Sakura accidentally destroys her dad's laptop in which he had stored all the research he had being working for days without sleep. The whole scene is played in an actual heartbreaking way, as she realizes this is something she simply has no way to fix.
In Higanbana No Saku Yoru Ni, Marie is sexually abused and blackmailed by her teacher, who tells her that no one would believe her if she told. And then said teacher murders her when she finally threatens to tell someone.
Invoked in a flashback in Fruits Basket. Tohru's mother Kyouko comes from an abusive household where her parents heavily neglected her and kicked her out of home right before her then-counselor and later-husband Katsuya came to ask them for marriage approval, so once she finds out she's carrying a baby, she has a Heroic BSOD due to being terrified that her relationship with Tohru would go the way of hers with her own mother.
For a double-hitter, while Kyoko is a good mother to Tohru, she dies not long before the series starts. Her last thoughts, as she lies bleeding to death in the road, are complete panic at the idea that her daughter will be left all alone and uncared for. This carries over to Hanajima and Uotani (who are Tohru's friends, but also act as surrogate parents at times), who are shocked to learn that while they thought Tohru was living with relatives, she'd spent a week living in a tent. Specially considering that Tohru's only relatives come from Kazuya's side... and save for her grandfather, they all hate her. (And when she has to stay with them for a while, they treat her like absolute shit.)
There's also the massive amounts of abuse in general, and specially child abuse/neglection, both physical and psychological. Most of the characters are able to escape or overcome it by the end of the series, but it's still horrifying, especially considering how well most of it is covered up. And it's made even worse when the biggest of the abusers... turns out to have been one of the most abused victims. For a really selfish and petty reason, too.
Detective Conan has several things involving Conan or other children being in danger. Conan has been held at gunpoint or knifepoint by a murderer or taken hostage several times, and more than once said murderer would have no problem silencing Conan or another child for being witnesses.
Many cases have children or teenagers as either victims of murder/injury/etc., or as witnesses of murder/injury/etc.. In the first case types, someone whom they loved will kill to attempt to kill the Asshole Victims as punishment; in the second ones, the now grown-up victims will exact revenge themselves.
The 15th movie has Conan being Buried Alive under an avalanche and everyone rushing to find him before he runs out of air. And said movie has the attempts on the life of an amnesiac fifteen-year-old boy as one of the biggest plot points.
Also there's the fourth movie, Captured In Her Eyes, where Ran, the one who always takes care of Conanand Kogoro, is struck with Trauma-Induced Amnesia and can barely handle herself. Seeing someone who has always been there for you need help desperately, but you can barely do anything for them... ack.
There's the Murdered Stage Magician case. The victim's six-year-old daughter, whom the killer sort-of used to make the victim surrender to him so they could kill him? The little girl has disappeared. And the murderer is the one who has her. It's a BIG relief when said killer brings her back unharmed.
The premise of the series in general is this. You're in a place that should be very public and friendly, only to be attacked and nearly killed. You cheerfully go off somewhere alone and promise to meet your best friend later, only to all but vanish for who-knows-how-long. Against all odds you manage to survive something that should have been fatal, only to find that you can't go back to your old life. Instead, you have to watch as your friends cry and wonder where you are, while you can't say a thing to them. Because if you do, they will be targeted by the same evil group that did this shit to you.
Fantastic Children: A 5-year-old child just disappeared without a trace and 6 years later his/her corpse was found amongst other children's. There have been many parents who had to experience this throughout history since the 15th century. In one of the cases of missing children the police refuse to pursue the case further and conclude that the child left on his own, using his then 3-year-old sister's words for their convenience.
It gets worse thinking about Sara in the end. She may be trying to show the kids of this hellscape that there's always some glimmer of hope out there...but as far as her parents back home know, she was probably kidnapped, murdered, and disposed in some remote location.
This happens in Wandering Son from time to time. Imagine your nine year old daughter goes to the local city without telling you, dressed as a boy, and the first thing that happens is she's hit on by a an adult. To make matters worse she and her friend go around hanging with them, even sleeping over at their house and being gone all day, without telling you. Thankfully Yuki is nothing but a playful tease and she would never harm either child, but..
Interestingly enough, Pokémon Special has this fear belong to one of the main villains, Giovanni - his son was abducted, and at least one of his villainous schemes even stems from his desire to find him. It also briefly plays on the fear that, after you've been separated from your child for so long, they might not like you or want anything to do with you now that you've re-entered their life - because while he eventually comes around and accepts his father, deciding to involve him in his life, Silver initially rants about how unfair it is that he'll never have a perfect family and that he can't possibly accept that his father is such a renown criminal (while Giovanni is in the same room, in perfect hearing distance, though unconscious).
Spirited Away has one scene where Yubaba frantically searches her son's room while believing he's been kidnapped.
Ryuunosuke and Caster in Fate/Zero are serial child murderers who like to give their victims a Hope Spot before brutally killing them. In one episode, you even see a memorial service for one of the victims, who happens to be one of the young Rin's classmates. It's just a single photo frame, and you hear someone mention that they coundn't do a proper burial because the body was too mangled. It gets so bad that, in-universe, a reward is offered to whoever can kill Caster first, and the entire Holy Grail War is put on hold until then. Cue nearly everyone doing an Enemy Mine to take these two down.
In Kodomo no Jikan, despite allReiji'sfaults, when Rin is in any danger, real or imaginary, he really freaks out. On the other hand, Reiji himself is no small cause of nightmares, with his disturbing and unhealthy interest in Rin.
While it's generally Played for Laughs, it's heavily implied in Axis Powers Hetalia that the nations have no choice but to obey their bosses, meaning that the characters all live in a world where their best friends or even family members could turn on them in an instant. When the series was in its webcomic format, it was played very seriously in the story of China and Japan. China raises Japan and considers him a little brother, only for Japan to show up in the middle of the night and attack China with a katana. China has no idea at all this is coming, and is inviting Japan inside for some food when the blade is drawn.
The core of Ayashi no Ceres is this. A woman's kind and endearing husband becomes so obsessedwith her that he starts restricting her behavior, like locking her in the house to prevent her from talking to men who aren't him, to beating her, forcing sex on her, and going so far as to killing one of their kids out of fear that the little girl would take her (Ceres) away from him (Mikage). This manga is a story of Domestic Abuse.
And on the anime side: after a disastrous mission, a very pregnant Aya comes home to an empty apartment. Her boyfriend Toya's shoes are by the door, his toothbrush is in a cup by the sink, his mug is on the counter, but he's not there, and he'll never be again. That's gotta be pretty high up the list of Adult Fears for most of us—having to come home to all the memories alone.
Welcome to the NHK presents its viewers the consequences of being a hikkikomori for the rest of your life: Growing old, ugly, still living with your parents until they die and eventually homelessness.
On Yamazaki's side, it's the fear that your dreams and aspirations are futile and you shouldn't even bother because, like it or not, your life has already been decided.
With Hitomi, it's the fear that her life has no meaning. With Megumi, it's constantly being exploited by con artists and desperately searching ways to make income to support yourself and a parasitic relative.
Life is just full of this. The manga centers around bullying and self-harm. After her friend betrays her in a jealous rage Ayumu begins to cut herself. Once she enters high school she meets a girl who acts like her friend but turns out to be a bully in disguise. None of her family members know about her turmoils. To make matters worse, the teachers try their best to downplay the bullying and make it seem like nothing is wrong.
In Digimon each season has one or more adult fear aspects to it especially in Adventure.
Digimon Adventure: Your child/brother/friend leaves home to risk their life in battle, and all you can do is stay at home, far away from them, and pray for the best.
Digimon Adventure 02: Your oldest son dies in a car accident at the age of 7 and then his younger brother starts getting a lot better at school and sports, similar to how his brother was, and while years later he is considered a teen celebrity because of his talents he isn't quite himself anymore and he has been getting more and more distant lately. Then one day he dissappears after leaving a note that almost sounds like he may be attempting suicide and when he finally does come home weeks later from who knows where he has no idea who you are anymore. Later on lonely little children start being approached by strange looking adults and when they come home they seem different and more violent then they used to be.
In the Street Fighter IV OAV The Ties that Bind, Ken and to a lesser extent Guile are slapped to the face with this when Ken's wife/Guile's sister in law Eliza disappears. It's worse when it turns out she was kidnapped. By Crimson Viper. Who, at the start, had posed as a Hot Scoop who had just spoken to Ken himself. Moreso, Eliza has just found out that she's pregnant. The imaginery of Kent speaking to Viper on the phone while the camera pans to a couch that has Eliza's knitting stuff on it and to a small doll that sits on the fireplace is pretty powerful.
The first episode has a rapist actually rape someone on-screen.
Another episode has a man who has been the Butt Monkey for years at his job finally snap and go on a killing spree at work.
One arc has an all women's college, where parents and students alike become terrified of a Serial Killer turning the girls who attend the school into deranged plastic art (and yes, the process of turning a person into plastic kills them). Turns out the Serial Killer was under everyone's noses the whole time (the student and local Mad Artist Rikako Oryou); this leaves almost everyone who knew her feeling betrayed and scared.
Episode 12 has Yayoi finding out someone she loved was rebelling against society through music and Molotov Cocktails. The person in question was also implicated in murder.
Even worse in that episode is the first real insight into the conditions the asylums operate under. Yayoi, in her cell, is locked away without access to the outside world, or anything to do to entertain herself, especially her beloved guitar. When she shows even the slightest bit of distress over what amount to her imprisonment, the room is gassed and the tannoy tells her to start calming down, and that doctors would be on their way to help her. The final situation is a place you are sent to where, if you show any free will, you're drugged into submission with cold, clinical efficiency.
Episode 13 has Akane dealing with the fallout of losing a friend, and then having to repeatedly relive the memories of watching a close friend die.
One of the main characters is revealed to have had his father go insane with grief about his society and shame his family. The character is Ginoza and his father is Masaoka, who now works under Ginoza.
A death of a Posthumous Character turned Shinya from an idealistic and law-abiding citizen to a despairing Blood Knight who is despised by society and is wracked with grief due to his friend dying.
Episode 15 plays on many Adult Fear scenarios; like those who feel wronged by society violently attacking those who society has favoured, crime sprees, people losing faith in society and law, mass riots and ultimately the threat of societal breakdown.
Another Wham Episode, Episode 16 shows what it would be like for your life to be potentially saved by someone you trusted and respected, just for them to then kill you.Poor Shusei.
Yet another Wham Episode, Episode 18 shows what it would be like to find out the police department and the government is not only highly corrupt, but will try to have you killed when they find out you know too much or even if they think you could be detrimental to their plans.
Episode 21 shows how a father can try to save his son who he has a bad relationship with, and then die in front of said son trying to prove he loves his son...and how he can die before his son can even acknowledge him as his Dad. The relationship between Masaoka and Ginoza was mostly professional, but Masaoka's last words show how he wished it was father and son. Ginoza afterwards seems to feel the same.
Watching your children or other relatives die while you are powerless to stop it;
Having your family members threatened;
Being rejected by everybody and dying completely alone;
Having your friends and family turn on you, or having to turn on them;
Dying horrifically and pointlessly owing to circumstances beyond your control;
Losing everyone and everything you know and love;
The idea that people, no matter how nice or friendly they may seem, will commit unspeakable acts of violence and depravity, if the chips are down
In Xam'd: Lost Memories, there's quite a bit of this. The clearest example is in how the teenage lead characters, for one reason or another, all end up having to leave their families behind to participate in the war effort. Their parents know that they are in danger and could get killed, but there's nothing they can do to stop it.
Yuno, who stalks and obsesses over Yukiteru to the point of creeping him out. Mind you, real-life stalking and possessive lovers are NOT fun things to deal with.
Even worse when you learn why this particular possessive lover came to be. She was massively abused by her very messed-up adoptive parents, and one single act of kindness from Yuki coming right after she killed her parentsand abusers.
Tsubaki's backstory can hit too close for comfort for victims of rape. And then she tries to inflict the same gang-rape she suffered on Yuno. Yes, she may be an Ax-Crazy yandere, but even she doesn't deserve that! Imagine being in Yukiteru's shoes, especually when he hears Yuno's terrified screams, and especially in the anime where she's stripped down to her underwearwhile resisting and screaming—poor Yukki has to witness the sight of that, but thankfully savers her in the nick of time.
School Days will make you groan if you've ever had someone cheat on you, or had the fear of your romantic partner cheating on you. In one particular Wham Episode, Kotonoha scrambles to the school roof, excited to see her recently-hooked-up-with boyfriend Makoto, only to find out he's getting particularly dirty with Sekai. She has a very justifiably horrified face when she catches the two of them.
In Dragon Ball Z in the Saiyan Saga, Chi-Chi having no idea where Gohan was for a long period of time and having no way to contact him.
Also, Goku and the others (Krillin, Bulma, and Master Roshi) watching Gohan (as a 4 year old) getting kidnapped by Raditz.
Gohan gets his own when he grows up. After a traumatizing childhood where his mistakes have gotten people killed, Battle of the Gods has him getting drunk and making a mistake that nearly gets his wife and daughter killed. He's Immune to Bullets, but instead of catching them when he's shot at, he deflects them, only for the ricochet to hit Videl, who can be injured by bullets and who also happens to be, unbeknownst to Gohan, pregnant.
Although he rarely expresses anything outside of arrogance and anger, Seto Kaiba himself has one. Whenever his brother's life is at stake, he's terrified he will lose him. Being orphaned at a young age and a Parental Substitute to Mokuba are good reasons why he'd be scared to lose the family he has.
Clannad utilizes several scenes very effectively such as when Nagisa is left standing in the rain after Tomoya basically ditched her. Given that she's been very prone to being sick all her life, usually to the point of missing LOTS of school (hell it's practically a plot point), it's understandable when both Tomoya and Nagisa's parents freak when they realize this. There's another scene where Kotomi's parents die and her last words to them were "I hate you" because this happened after quite a fight; her resulting breakdown is quite understandable. The last example here, and quite frankly the most emotionally moving, is when both Nagisa and Ushio die, though at different parts of the series. Watching them slowly die is gut-wrenchingly saddening, it's surprising your actual guts aren't all over the floor after the respective characters die. Knowing that people you care about are dying and not being able to do a single damn thing about it is something that is enough to make anybody give up on life as what happened with Tomoya, our battered Break the Cutie scene that's been dragged through the proverbial mud much of his life.
The final arc of AIR. While its cause may be supernatural, the adult fear Haruko is made to confront is very real: that of caring for a child through an incurable illness, knowing that she'll ultimately die no matter what you do for her.
The ending to Satou Kashi no Dangan wa Uchinukenai provides an example of this. Mokuzu is murdered by her father. There were numerous signs that he was abusive but no one saved her. She had a permanent, painful limp due to a hip injury she received as a baby and had a ruptured ear drum which caused her to be partially deaf. Child services had been called on her father but she stood by them, and her mom left them. Even in her new town there were rumors he was abusive, some even wondering if he'd end up killing her one day, but still no police were involved. Mokuzu has absurd, outlandish behavior (such as saying she is a mermaid or randomly singing) but no one saw it as related to abuse or a sign for help until it was too late.
In Cyborg 009, the heroes were abducted and forcibly turned into cyborgs because they could easily disappear without it being noticed. Except for 003, none of them have friends or family in positions to report their kidnappings. Speaking of 003, her brother watches her being chloroformed and dragged into a car. He tries to save her, only to lose the chase because he happened to pick a plane that didn't have fuel in it. Oh, and the Black Ghost operates on a global scale, so there's pretty much no chance of the various abductions being put together in some way to find a common thread.