Gundam SEED Destiny: Its main character Shinn Asuka experiences hardcore cynicism catalyst when his little sister Mayu is accidentally blown up alongside their parents when they got caught in between battle fire. To the point where Shinn carries around her cell phone and listens to her "leave a message after the beep" recording when he gets down.
It is lampshaded upon in Super Robot Wars Z, after being taken out of his berserker streak by Stellar Louissier if they saved her earlier. When back at base, Shinn's girlfriend Lunamaria Hawke is concerned that Stellar is going to be a contender for Shinn's heart, but Shinn tells her that he sees Stellar as a platonic brother-sister relationship. Making up for your mistake theres huh Shinn?
Ho from Tower of God feels guilty for not being strong enough to protect his friends from a berserk stray warrior. It has made him rather jealous and loathing towards anyone with greater power than him, especially Baam.
Himiko Kudo from Get Backers. Backstory is that Ban killed her brother, Yamato, while they were all thieves together.
Dias's motivation in Star Ocean EX was his dead sister.
Mikagami from Flame of Recca, whose older sister died early. At some point before his Heel-Face Turn, he kidnaps Princess Yanagi and forcibly cuts her hair since she looks a lot like his sister.
Soukou No Strain gives Lottie a dead older brother. Sara's dead schoolmates also fit the "failed to protect" mold, giving her post-traumatic stress syndrome for a long time afterward.
Chester, the archer in the anime adaptation of Tales of Phantasia, is driven incessantly by his need for revenge after Mars kills his little sister (his only family) while he is out hunting with the main character. He is so driven that he appears to give up sleep entirely, instead using the night to practice his bowmanship.
The main character of Blade of the Immortal put down his sword after his Bounty Hunter lifestyle led him to accidentally kill his sister's husband (he'd never met him before), causing said sister to mentally revert to a child-like state to cope. He picks it back up after his refusal to fight later resulted in his sister being graphically sliced to pieces. The story deals with his need to balance the two extremes; of course, the whole thing leans more towards violence, but generally it's for a good cause.
In Martian Successor Nadesico, a young girl named Ai whom Akito meets in an underground shelter shortly before it's attacked by enemy Mecha-Mooks serves as a kind of Cynicism Catalyst to him. Eventually it turns out that she didn't die, but instead was sent first forward, then backward in time, and grew up to be one of the major characters, the local Hot Scientist, Inez Fressange.
Rurouni Kenshin: Yukishiro Enishi became obsessed with getting revenge on Kenshin after he accidentally killed his big sister Tomoe.
Naru Taru has Shiina Tamai's older sister, Mishou, who died few after Shiina's birth. Her death tore the family apart and it'd take more than a decade and another death to patch things up.
Neo Saiba's digital world takeover in the manga Digimon V-Tamer 01 is motivated by his little sister who is in a wheelchair.
In Noein the pseudo-villain/anti-hero Atori watched his little sister step on a land mine. Atori's attachment to Miho is most likely due to her resemblance to his dead sister.
In Gunslinger Girl the brothers Guiseppe and Jean are both seeking revenge for the death of their sister Enrica at the hands of terrorists. The names of their chosen weapons, the cyborgs 'Henrietta' and 'Rico', reflect this. The difference is that Jean is cold-blooded towards Rico (deliberately), whereas Guiseppe has created a surrogate in Henrietta, even (in the manga chapter "Fantasma") making her wear one of Enrica's dresses. Though Jean is visibly shocked by this act, he is unable to find the strength to reprimand his brother.
In Saiyuki, Hakkai's sister and lover Kanan was kidnapped and raped by youkai, and not wanting to give birth to a youkai child, killed herself right in front of him. This event left him hurt and with feelings of rage that he tries to put away.
Pokémon: The First Movie's backstory. Mewtwo wasn't the only thing being cloned; a little girl who died in a car crash and three other Pokemon were as well. The four became friends via Mewtwo's psychic link, but the experiment went wrong and all but Mewtwo died. To really drive the nail home, the scientists unintentionally induced Laser-Guided Amnesia on him when they stabilized him, leaving him only with a subconscious memory of a friend who died for nothing. This did not end well when he was finally released and was told they're gonna experiment with him.
All the Claymore share more or less the same Dark and Troubled Past : family murdered by Youma, exiled from their village, and then are forced to become Half-Human Hybrid. That means that each Claymore has her complex and Cynicism Catalyst. A significant part of the story is about the various way each of them react with that, such as starting a Roaring Rampage of Revenge, feeling guilty of being the only survivor, or going Knight Templar.
In Dr Koto, a journalist come to ruin Koto's life again, full of bitterness after his little sister died from Koto's lack of care.
In the manga and anime Project ARMS, Ryo Takatsuki goes on a brief downward spiral after believing he caused the death of his childhood friend and girl he loved Katsumi. When it turns out she was really alive, he spends most of the series traveling from Japan to America with his friends to rescue her, only to watch her be killed by his own hands by accident (the bad guy threw her in front of himself as Ryo attacked), which causes Ryo to nearly bring about the end of the world out of his guilt and sadness. Then, when it turns out she's not dead again but is implanted with ARMS of her own and kidnapped by the evil organization Ryo's been fighting, he must again battle his sadness while setting off to rescue her. Wow.
Konan and Nagato/Pain became villains after the death of their best friend Yahiko, when their faction was betrayed.
The death of his beloved Rin is what sent Obito off the deep end and what directly motivated him into becoming Tobi.
Gaara was pushed over the edge when his uncle tried to kill him when he was little, claiming that he hated him for causing the death of his mother (his uncle's sister), who also hated his very existence.
Neji's dad died when he was little in order to placate Kumogakure and avoid another war; his uncle Hiashi, the head of the family, had killed a Kumogakure dignitary who tried to kidnap his daughter Hinata to steal her Byakugan, but then Kumogakure demanded the body of the killer, most likely to get the Byakugan, and Neji's father ended up substituting for Hiashi, his twin brother. As a result, Neji started hating every Main Branch member.
Kakashi became obsessed with the shinobi code and began placing the mission above his teammates after his father committed suicide, having become ostracized and falling into despair for failing a mission to save his comrades.
Izuna was his brother Madara's entire world. Madara is the man he is today because of Izuna's death.
Both Orochimaru and Sasori were ultimately messed up when they lost their parents (individually, they're not brothers, but the circumstances of loss are basically the same, and they were, to an extent, initially motivated by a desire to get them back).
Tsunade lost both her brother and her lover, who had sought to protect the village as Hokage, and she turned her back on the village and began to view the title with disdain as a result.
In the pilot, Kuroda was friends with Saburo, a fellow artist, but Kuroda got stabbed by Saburo when he was chosen for the Council on Cultural Advancement, in the hopes of getting his job back. Kuroda survived, but became bitter and refused to trust others. Saburo was also deeply affected, painted "Symbol" to symbolize his hopes of reconciliation with Kuroda, and then was Driven to Suicide.
In Fushigi Yuugi, Nuriko's dead sister Kourin inspires appearance. And Tamahome receives a power-up once Suboshi kills his family, ending with Tamahome's youngest sister. And for worse, Suboshi killed them because he blamed Tamahome for the apparent death of his older twin brother, Amiboshi. We later learn that Nuriko became a Cynicism Catalyst (in the form of a dead little brother) for his surviving sibling, Ill Boy Chou Rokou.
In Et Cetera, Baskerville's younger sister was an Ill Girl whom he was trying to save. He joins the Syndicate in order to get access to a medicine for her, but it turns out the medicine was a narcotic that quickened her heart rate and worsened her condition, eventually killing her.
In Gundam 00, Lockon Stratos's younger sister Amy and their parents were killed in a terrorist attack when he was a child. He's normally the cheery big brother of the team, but give him a chance for revenge...
Subverted by Lockon's younger brother Lyle. He does mourn for the deaths of Amy, their parents and Lockon himself, but decided not to specifically seek for revenge over them. In fact, at the end of the series Lyle shoots Lockon's murderer Ali Al-Saachez to death, but it's less to avenge his brother and more because he does offer Ali a Last-Second Chance, Ali doesn't take it, and so he simply sticks to his word and his guns.
Kotori as a dead little sister becomes Kamui's cynicism catalyst midway through X1999. Her older brother, Fuuma, was the one who killed her.
Actually, Kamui and Kotori's case is an inversion of sorts. Before her death, Kamui is apathic, at most, to his role in the End of the World. While he does take a side before her death, it's the event itself that makes him determined to protect his loved ones that are left, and, thus, to embrace his role as a Dragon of Heaven.
In the first Tokyo Babylon OAV, Broken Bird Kazumi Asou has a dead older brother, murdered by his co-worker ShinjiNagumo in an attempt to remove him from competition in their high-class work. In the second, the Serial Killer's Start of Darkness happens when he accidentally kills his little sister as a child, strangling her to death while they were playing and only being discovered when their mother returned home from buying groceries.
Yu-Gi-Oh!: Alister/Amelda joined doom to get revenge on Kaiba for the death of his little brother, later revealed to have been killed on Dartz's orders as part of a massive Gambit Roulette. In fact, Dartz did something like this to nearly all his henchmen, covertly ruining their lives and then swooping in as a Dark Messiah. Mai's Marik-related PTSD was the only part he wasn't responsible for.
In Robotech: The Shadow Chronicles, Marcus Rush has a dead big sister - namely (original) Marlene who was killed by the Invid at beginning of Mospeada, which is the reason he hates Invids so much. This results in quite a few rage attacks.
In Zetsuen no Tempest, Mahiro doesn't care about saving the world and just wants to kill his sister's killer - not to get revenge or because she'd want him to or anything, but because it wasn't fair. He doesn't seem to care much that his parents were also killed, though. Interestingly, it turns out the sister was also protagonist Yoshino's girlfriend, which is the reason he ends up joining Mahiro.
In Paranoia Agent, Lil' Slugger comes about and ends up destroying Tokyo because Tsukiko felt guilty about her puppy dying when she was a child.
Edward Elric from Fullmetal Alchemist has two major Cynicism Catalyst events: the failed attempt to revive his mother through human transmutation that resulted in him losing an arm and a leg and his younger brother Alphonse being reduced to a soul attached to a walking suit of armor, and the horriblefate of Nina Tucker.
Chōji Suitengu from Speed Grapher only maintained sanity throughout his years of hellish service in the military by thinking of finding his little sister Yui again after he got out. When he finally does, Yui is so utterly broken by her ordeal that the only thing he can do for her is end her suffering]], turning him into a callous bastard and the Big Bad of the series.
Halle Lidner from Death Note. She wishes to take down the Kira organization by joining the police force. Why? One of her relatives was killed by none other than Kyosuke Higuchi at the time when he acted as Kira.
More or less the cause of all of Bird's Nest's angst in Copernicus Breathing, although it is up in the air as to whether or not Bird's Nest just feels guilty about and is having trouble moving past his little brother's death or if he actually killed Michel.
Angel Beats!: Yurippe. In her case, the catalyst were two dead little sisters and one little brother. The murder of her younger siblings led to her creating the Afterlife Battlefront in the first place.
According to Puella Magi Oriko Magica spinoff Noisy Citrine, Kirika's downward spiral into antisocial depression and madness began when she caught a closely trusted childhood friend shoplifting at the mall... and said friend literally left her holding the bag, to be caught by security in her place.
Doubly subverted in Berserk with Guts. Guts first traumatizing experience was at the age of 6 or 7 when he was raped by a male soldier at the convenience of his adoptive father Gambino. After this, Guts had almost lost all of his trust in people. In his teen years, he joins the Band of the Hawk and over the course of the story line, Guts' trust in people starts to build up as the themes of camaraderie,friendship,and love prevail. Tragically, an even greater and more horrifying event happened during the Eclipse, where all of his friends were sacrificed and eaten by hoards of demons and his lover was horrifically raped to insanity in front of him at the convenience of his former best friend, Griffith. This event all but utterly crushed Guts' spirit. He willmost likely neverfully heal after this one.
In Saki, flashbacks show that Teru Miyanaga, the eponymous main character's older sister, was once cheerful and kind to her younger sister, but in the present day, after their parents have separated, she is aloof, refuses to speak with Saki, and even denies having a sister. The exact cause has not been revealed yet, but this montage◊ implies the reason, by introducing a third girl who most likely died in a past incident.
In Sangatsu no Lion, the deaths of his parents and sister are a large part of what sets up the foundation for Rei's negative outlook on life, and forcing him to consider things no kid would normally do, such as lie about his own interests in order to avoid being institutionalized by his surviving family.
Magneto Magneto's Cynicism Catalyst is the Holocaust and other tragic events. After he escaped Auschwitz, he got married to a Gypsy girl named Magda who also ran away from there, moved to Ukraine with her and tried to continue living his life. Then his daughter Anya was killed by a mob and Magda left him after he crossed her personal Moral Event Horizon by killing them all. Even then, it was still several years (and other crap getting piled on him) before he went completely batshit. Some consider his Moral Event Horizon that turned him into the Big Bad working for the CIA to capture Nazis. He captured one that was working for the United States. As punishment for 'crossing the line' (the captured Nazi was working with the CIA to best the Soviet Union), Magneto's handler killed his lover and tried to kill him after giving him a "The Reason You Suck" Speech. Antagonizing Magneto thusly was not a good idea and it did not go the way the CIA expected.
From the X-Men, Colossus, the big armored Russian: when his younger sister and local Dark Magical Girl Illyana/Majik died of the Legacy Virus in the early 90's, he went all gloomy and pulled a Face-Heel Turn to join Magneto's side for a while. He then got back, and then he died. And got back again. It's complicated. Illyana came back as well. It Makes Sense in Context.
In the comics, Snake Eyes from G.I. Joe carries a picture of his twin sister with him during his service in Vietnam, as a good-luck charm. When he comes back home, he learns that his entire family has died in a car accident. And that's just the beginning for him...
Late in Y: The Last Man, we discover that Alter Tse'elon's whole military career and militarist attitude were caused by the accidental death of her (older) sister during a pro-Palestinian non-violent demonstration she was participating in.
Lara, the little girl who secretly rebuilt the battered robot paratrooper Mongrol in ABC Warriors. Her death, compounded with the electric torture that fully returned him to live, took such a toll on his psyche that he was left a single-mindedly violent monster who knows only rage and confusion. According to the narration, in his broken mind he sees and hears Lara always, encouraging his quest for vengeance against the enemy forces that killed her.
52: Black Adam's origin story features the deaths of his wife and children, sending him over the edge.
The Flash villain Captain Cold has always been, as the name implies, a cold-hearted, merciless SOB. He's become even more so since his younger sister, the Golden Glider, was murdered. In one issue, he tracks down, tortures, and murders her killer. A few panels later, he's at home, tears running down his face, saying: "Much as I hate it, my heart's not always cold."
Various retellings of Doctor Strange's origin story give him one to explain how he became Dr. Jerk. In the first version he didn't have any real excuse; he was just an ass.
In the comic Madame Mirage the titular character is revealed to be a semi-sentient hologram created by a vengeful young scientist who modeled it after her murdered older sister.
Although later comics establish that he had plenty of issues beforehand, getting half his face scorched off by acid thrown at him by a vengeful mobster was the inciting incident that turned noble and upstanding district attorney Harvey Dent into the cynical, nihilistic gangster Two-Face.
Films — Animated
In Ice Age, one of the protagonists of the trio, Manny, was revealed to have his little son and wife killed by a group of Neanderthals.
Films — Live-Action
In Kiss Kiss Bang Bang, the death of Harmony's little sister Jenna drives the plot. What made Harmony all kinds of screwed up and guilty was that she couldn't protect Jenna from their father, and then Harmony skipped town as soon as she was sixteen, leaving Jenna alone with him.
Underworld: Selene's entire family was brutally murdered by Lycans, leading her to mercilessly hunt them once she became a vampire. Turns out Viktor, who turned her, was the one who actually killed her family.
Colonel O'Neil from Stargate originally left the military and went basket case because his son accidentally killed himself with O'Neil's own gun. He only joins the mission to the alien planet (from which there is little chance of returning) because he's downright suicidal.
In Lady in the Water, after reading Cleveland Heep's diary, Story learns that he became depressed and withdrawn from society after a burglar broke into his house, robbed him, and murdered his wife and children all while he was not home (which he blames himself for).
In A Short Film About Killing directed by Krzysztof Kieslowski, the young man on death row espoused a life of crime because he was so haunted by his dead little sister's memory.
In Top Gun, Maverick's angst during the second half of the movie comes from his feeling of responsibility over his RIO Goose's death.
Hannibal Lecter is given a dead little sister "Mischa" during Hannibal, causing a great deal of Badass Decay. Not enough to stop him from going on another killing spree, however.
Star Wars: In Revenge of the Sith, the fear of the loss of Padmé Amidala by childbirth is what drives Anakin Skywalker over the edge to The Dark Side. Before that, there was the death of his mother in Attack of the Clones which started his descent. For extra irony, she dies from childbirth because she loses her desire to live after seeing the monster Anakin becomes in trying to prevent her death.
Lakeview Terrace is about a cop (played by Samuel L. Jackson) who will go to any lengths, including intimidation, violence, and murder, to get the interracial couple who just became his new neighbors to move. The event that ultimately drove Turner to focus his rage on the couple is revealed to be the death of his wife, who was killed in a car accident while on her way to meet her white boss who she was having an affair with.
In Face/Off, Castor Troy's accidental murder of Sean Archer's son is a key event in the backstory of the two characters. Later in the film, Sean!Troy kills Castor!Archer's younger brother and partner-in-crime Pollux. Castor!Archer also killed his ex-girlfriend Sascha's brother Dietrich. When they confront each other in a church all three of them bring this up.
Castor: Look, your son's death was an accident. I wanted to kill you. Why didn't you just let it go or kill yourself?
Sean: No father could.
Castor: No brother could either.
Sascha: Neither could a sister.
Eddie Valiant in Who Framed Roger Rabbit was revealed to have held a bitter grudge against the Toons after his brother was murdered by a toon.
Pentecost's sister was one of the fighter jet pilots who lost her life during the first Kaiju attack. Her death was what caused her brother to work with the military to find the best way to combat the Kaiju.
Yancy is this for Raleigh.
Tendo Choi lost his grandfather to Kaiju blood in the prequel comic.
Split Second: In a flashback it's shown how Stone was fairly well-composed before his partner was killed by the monster he has since been pursuing. Stone blamed himself (especially because he was having an affair with his partner's wife) and became a paranoid, rude gunslinger in response.
The Children of Húrin and The Silmarillion: After his beloved younger sister Urwen dies from a plague, the boy Túrin Turambar starts to develop a grim and bitter personality which contributes to much disaster in his later life. Ultimately he is Driven to Suicide, just after the death of his other little sister.
Wendy Torrance in The Shining by Stephen King lost her sister Eileen when she was run over by a car: Eileen was six, Wendy ten at the time. Wendy thinks that's probably the reason her mother became such an insufferable bitch.
Inverted in Harry Potter and the Deathly Hallows, in which we learn that Albus Dumbledore was well on his way to becoming a villain, only to have the death of his little sister Ariana (for which he either he, his brother, or his evil best friend Gellert Grindewald was guilty) give him a giant wake-up call and turn him around into a hero.
A Christmas Carol: Fan Scrooge, who is said to have died in childbirth in some film adaptations. This event triggered/hastened Ebenezer's downward spiral into misery, and he especially hates his nephew/her son Fred for it.
The Catcher in the Rye's Holden Caulfield is angry, depressed and prone to failing out of school largely because of his little brother Allie, who died of leukemia.
King Arthur myth: The accidental slaughter of three of Gawain's younger brothers turns his long rivalry with Lancelot into a vendetta. This fight between the two chief knights leaves the Round Table open to attack, letting Mordred worm his way in and destroy everything. (The theme of revenge is slightly subverted in that Gawain is the one who ends up dead.) Arthur doesn't attack Lancelot until he rescues Guinevere from being burned alive for adultery, and takes her to Joyous Gard, his realm. Sources debate on whether Arthur was counting on Lancelot rescuing the Queen or not.
From the books of Dale Brown, Patrick McLanahan's little brother almost getting killed is what gets him started on a vigilante quest using the titular Powered Armor of The Tin Man. Eventually, both his wife and brother get killed.
Sandor Clegane's little sister's death at the hands of their own older brother, Gregor is part of the scarring childhood that created the cynical persona the reader meets.
Eddard "Ned" Stark has a good dose of this; while he never became a cynic after Lyanna's death, the man does know how to angst.
Oberyn and Doran Martell, who wants revenge on the Lannisters for the brutal rape and murder of their sister Elia. It's clear that Elia's death had a big effect on both of them, but particularly Oberyn, since he matured quite a bit afterward.
In The Purple Widow, Glen O'Brian, a servant at the palace of Tommikia, reveals that his two younger sisters (along with his mother) were burned at the stake for trying to escape imprisonment for false charges. Why, why is it always Glen?
In Poul Anderson's "Time Patrol", the death of his fiancée caused Whitcomb's melancholy and willingness to join the Patrol.
Ankaa is this for Virgil in Within Ruin. Her death is the driving force behind the entire plot. Sadly, she is disgusted by everything he has done to resurrect her.
In Alethea Kontis's Enchanted, Tuesday's death hit Monday very hard. It was her endless visits to the graveyard that led to her meeting up with a prince and turning into the bride from "The Princess and the Pea".
The death of Oscar Wilde's little sister Isola was reportedly a major catalyst for much of his darker literature, including his poem for her, "Requiescat".
American beat author Jack Kerouac had an older brother named Gerard who died aged nine when Jack was four. Jack's feelings about this loss show through in many of his books, and one of them, Visions of Gerard, is all about them.
The poet Seamus Heaney lost a younger brother to an automobile accident, and later wrote a gut-wrenching poem about it
In Summers at Castle Auburn, Corie takes one of her own potions that opens someone's eyes to reality. She blames this for her horrible realizations the summer she is seventeen, but it is more likely she just grew up enough to understand things.
In What The Raven Saw, the titular character was turned into the bitter cynic he is when his mother abandoned him to die, and no-one else in the world tries to help him.
From Honor Harrington, the death of her little sister Estelle is what turned Eloise Pritchart against the Legislaturists. A couple of revolutions, a Secret Relationship, and a lot of lying later, she rises to the top as the truly elected President of the restored Republic of Haven, the head of a government based on a Constitution that had lain buried for two centuries. She got her revenge, all right — and did a lot of good while she was at it.
In Those That Wake, Big Black was the tipping point that sent New York into a state of unending hopelessness.
The original Dark Shadows has Sarah Collins as the motivation for at least some of Barnabas' angst.
The X-Files does this, with Mulder's little sister's disappearance providing probably the biggest motive for a large portion of his adult life and career. He's a loner and sometimes exhibits jerk-ass-like behaviour in his Determinator ways, trying to reveal The Conspiracy, though he's really one of the very few good guys on the show.
Sgt Maritza Cruz from Third Watch had a younger, drug-addicted sister named Lettie, who died of an overdose — which caused Maritza to bend the rules even more than she usually did in order to find the dealer.
One episode of This Is Wonderland featured a man trying to get sent to a federal prison so that he could kill the man responsible for the death of his father and brother, but not his sister, who was still alive.
The Independents' crushing defeat at the Battle of Serenity Valley is presented as this for Malcom Reynolds in Firefly.
Mary Winchester was this for Sam and Dean's father John, only John went a lot more off the rails than Sam later did, probably because Dean was only four and not available to do the same level of stabilizing. (Time travel shows John used to be as clean-cut and youthful as Sam in the pilot—more so, actually, even after Vietnam.)
The two several-month periods Sam spends attempting to resurrect and/or avenge his big brother, in "Mystery Spot" and the season break before "Lazarus Rising," see him become Darker and Edgier to the point ofBlood Knight. He never actually makes a Face-Heel Turn, but he does start to tolerate a hell of a lot of collateral damage, and then commits the cardinal sin that unmakes any antihero: he was wrong.
There's also Gordon, with a nasty twist; he tells Dean about how he became a vampire hunter after they got his little sister - only to later reveal that they had turned (not murdered) her, and it was him who tracked her down and killed her.
The first episode featured Gunn (Charles Gunn) who had his little sister become a vampire, forcing him to kill her.
Holtz's daughter was turned into a vampire, forcing Holtz to kill her.
Inverted by Angel himself. One of the first things he did after being turned into a vampire was return home and murder his little sister. Well, after terrorizing the town a little, but she still trusted her brother Liam enough to let him in. Oddly, despite having clearly been rather close with her, Angel displays no issues one way or the other regarding little girls.
In NCIS Ziva says that she was revenge-driven and cold for a long time after her little sister Tali was killed in a Hamas suicide bombing. However, she denies Tony's allegation that this is why she joined Mossad.
In Star Trek: Enterprise engineer 'Trip' Tucker's sister was killed in the Xindi attack on Earth. This affects his behaviour throughout the season three 'war arc', most notably in "The Forgotten".
A flashback scene in Battlestar Galactica's Razor'' shows Cain's sister was taken by Cylons moments before the end of the First Cylon War. The fact that Admiral Cain keeps a folding knife she acquired during this incident shows it was a prime motive for her ruthless actions in the 'present day'.
On Heroes, a dead little sister is revealed to be the motive behind Angela Petrelli and The Company, and all the dickishness they've caused throughout the show. Turns out she's not dead.
Josh Lyman from The West Wing has a dead older sister named Joanie, who died in a fire while she was babysitting him. Josh feels unspeakably guilty about the fact that he ran out of the house and left her behind, even though he was only six or seven at the time.
Torchwood's Jack Harkness had a tortured little brother. He thought he was responsible for this, having let go of his brother's hand while running way from the creatures who tortured him; and (or so we were told) angsted over it ever since.
Fiona of Burn Notice has a dead little sister, Claire, whose killing at the hands of a British soldier caused Fi to join the IRA. This continues, sometimes subtly, to inform her actions.
Nate Ford, whose son died when the insurance company he worked for refused to pay for the treatment that could have saved him. This led to Nate quitting his job, divorcing his wife and becoming an alcoholic.
Parker had a brother who died in front of her after being hit by a car. This is found out by a fake psychic doing a cold reading, which Parker, given who she is, has no way of understanding.
Johnny McHale, a character from the third season. The episode "True Night," took this trope to the extreme. His moment involves the gang rape and murder of his beloved fiancee, Vickie, the contingent murder of their unborn child, and his own near-fatal wounding at the hands of members of the 23rd Street Killers, a street gang. He suffers a psychotic break and becomes a murdering vigilante intent on exacting his revenge on the 23rd Street Killers, though his memories of these actions remain foggy until he is confronted with them by the FBI team. When Rossi comments that his survival was a miracle, implying that he should be thankful to be alive (a twist on the "This isn't what she would have wanted!" exhortation), Johnny responds by screaming, "You think living was a MIRACLE?" He ends up incarcerated in a mental institution where he spends his days drawing pictures of his dead fiancee and calling her cellphone just to hear her voice on her voicemail message.
In one episode of the second season, JJ tells Morgan and Reid about how her childhood fear of the woods stemmed from finding the body of someone at a summer camp she worked at as a teenager. Turns out she was just messing with them and there was no real reason.
The murder of a rogue Division agent's girlfriend drives him to attempt to kill, Percy, Division's leader. This forces Nikita to have to stop him, as Percy has set up several "little black boxes" filled with sensitive information that would bring down the U.S. government, set to be automatically released in the event of his death.
This trope is what leads to Michael being recruited to Division in the first place; his wife and child were killed in a car bomb meant for him, and Percy promised to help him track down the man responsible. Nikita is the one who eventually helps Michael get revenge, and it is that plus Percy's lies that lead to Michael's eventual defection to Nikita by the end of season 1.
In Flashpoint, it was revealed that Sam had a sister who died in a car accident when he was young. When doing a mission, he froze when he saw a dead woman lying on the ground without her shoes, which triggered memories of his sister who had died in a similar position.
In a The Man from U.N.C.L.E. TV movie, "The Fifteen Years Later Affair," we learn that Illya Kuryakin left UNCLE after a betrayal by a double agent led to the death of the Innocent (a young woman) during a mission in Yugoslavia. When Napoleon Solo alludes to this while attempting to persuade Illya to come out of retirement, Illya punches Napoleon in the face.
Annie, Kirby's dead girlfriend in the Masters Of Horror episode "Cigarette Burns". She killed herself for reasons that are never quite explained, but her copious drug abuse seemed to have sent her in a downward spiral.
Al Calavicci in Quantum Leap. His younger sister Trudy was mentally handicapped and spent most of her life in and out of mental institutions, as was commonplace in the time they were young. When Al was old enough to gain custody of her, he went back to the institution for her but found out that she had died of pneumonia. The anger in his voice when he asks, "How does a sixteen year old girl die from pneumonia in 1953?" says a lot about how heavily the topic weighs on him.
Kazami Shiro became Kamen Rider V3 after Destron soldiers murdered his family, including his little sister. It prompted him to hunt down Kamen Rider Ichigo and Nigo, trying to convince them to turn him into a Rider-like cyborg.
Johnny Cash's older brother Jack died in a lumber mill accident when Johnny aka JR was twelve and Jack was fourteen. This affected Johnny throughout the rest of his life, and Jack Cash is mentioned in the liner notes of his 1996 album "Unchained".
Musician Eric Clapton's son died in a tragic accident when just a toddler, about which the songs "The Circus Left Town" and "Tears In Heaven" were written. Though close, this example subverts the Trope — particularly with "Tears In Heaven". Eric rarely plays it in public as he says he has tried to move on from a very sad period in his life and doesn't need the song anymore.
George Weathermay, one of the Ravenloft setting's greatest werebeast hunters, began a downward spiral into self-recrimination and depression when he brought his new fiancee home to meet the family, only to have her reveal herself as a lycanthrope and attack his young nieces. Neither girl died, but he blames himself and is now obsessed with tracking down and destroying this treacherous werewolf, whom he fears may have infected one of the twins with lycanthropy.
In The World Ends with You, the player is introduced to a pair of players named Beat (the older and slower one) and Rhyme (his younger female partner, who does all the thinking). Rhyme gets erased by Uzuki's Noise, and Beat briefly joins The Dark Side. It gets worse - Rhyme is actually Beat's kid sister, and it's his fault they were in the Reaper's Game to begin with - one day, she ran out of the house after they got in a fight, and ended up in front of an oncoming car. Beat dove into the street to protect her... and both of them were killed. In other words, Beat has doubled the guilt.
Wiegraf. As commander of the Corpse Brigade, he used to have enough honor to wish for the well-being of the troops drafted from commoners and peasants, and only campaigned for proper reparations for those left to rot by the nobles after the war. When he catches word of the death of his sister Milleuda, he loses his mind and seeks power at all costs in order to claim his revenge. But when Ramza later confronts him whether Milleuda would have wanted him to (literally) sell his soul, he says he has already moved past caring.
Final Fantasy VI does a bunch of this with Cyan, who was unable to save his wife and son in the siege of Doma. After an initial fit of berserker rage, he swears vengeance against Kefka for robbing him of his family. His latent guilt over the loss causes a Heroic BSOD later in the game, when the heroes must journey into Cyan's subconscious to slay his psychological demons, who turn out to be the Three Stooges.
Cloud's guilt over failing to save Zack and then Aerith inspires him more than once to complete inaction. Only an encouraging farewell from the two deceased characters at the end of Advent Children seems to have lifted this off his shoulders.
Vincent Valentine suffers from a grim backstory with regards to Lucrecia, though his response is the melancholic Goth to Cloud's Emo, and there's an element of the 'critical of the main hero's inability' to the two of them.
Subverted in the online mode of Dirge of Cerberus. The main character is driven to sacrifice herself to destroy the Restrictor on the basis of memories of her little sister being cruelly murdered, only for Shelke to tell her corpse that she never had a sister; it was an implanted memory to get her to remove the Tsviets' captor so they could go on to try to bring about the end of the world. Cruel.
Inverted by Shelke, for whom the sacrifice of her older sister is the inspiration for her to join the good guys and become Vincent's Mission Control.
Wakka lost his parents when he was still a kid, resulting in him getting a Promotion to Parent for his little brother Chappu. Even as Chappu became The Ace, still Wakka felt responsible for him and that he had to be a protective big brother. Then Chappu broke with Church teachings to join the Crusaders, who use forbidden technology in their fight against the Eldritch Abomination Sin, and died in his first battle. Wakka responds by blaming Chappu's death on the Crusaders' use of forbidden weapons, and becomes an almost fanatical follower of the religious laws who doesn't tolerate any challenges to the faith of Yevon.
Chappu's fiancee Lulu goes in the opposite direction by becoming deeply cold and cynical, and at one point she practically tells Tidus that Wakka is blaming "evil technology" for Chappu's death in part so Wakka won't have to acknowledge his own role or even Chappu's in the choices that Chappu made.
One of the reasons for Luca Blight's constant sociopathic Unstoppable Rage is due to the fact that when he was a child, he and his mother were kidnapped by mercenaries, who forced him to watch as his mother was raped repeatedly in front of him and later died giving birth to his half-sister Jillia. When he found out that said mercenaries were hired by Muse, he developed a profound, murderous hatred towards them and to his father, Agares, who cowardly fled when his family was attacked.
The Barows have their own example in Hiram, Euram and Luserina's older brother, who also got assassinated by Nether Gate during the same civil war. Their mother was bedridden afterwards, and it's implied that Euram's loutish behavior grew far worse following his brother's death, as he became heir apparent in his place.
The heavy amount of angst that the title character of Max Payne carries with him is a direct result of the murder of his wife and baby girl three years ago by junkies hopped up on the designer drug Valkyr, and was the reason that he joined the DEA in order to root out the source of the drug. And it only piles up with the rising body count. Some of the later plot points rely on it.
Martel's younger sibling turned evil following her death' variety. Intriguingly, her fiancée went the other way and started opposing her brother following her death, realizing fully well that the insanity that resulted was definitively not what she would have wanted.
The death of Alicia, Regal's fiancée, who he killed after she was mutated into a monster and begged him to kill her caused Regal to become The Atoner to the n-th degree. He eventually makes peace with her ghost, who is in a position to tell him that she didn't want him to torture himself in that manner personally. He keeps torturing himself, though. At least until the Big Bad is taken down, in which he's fulfilled his promise to atone for his crime.
Kratos being forced to kill his wife Anna, along with the assumed death of his son Lloyd, caused him to lose all hope in creating a better world on his own and return to Mithos and Cruxis.
Chrono Trigger: Prince Janus of the Kingdom of Zeal, better known as Magus, was a moody little boy until he got catapulted into the future and lost his older sister Schala in time. Everything he did since — ruling the Fiends, declaring war on Guardia, summoning Lavos, disguising himself as a prophet (complete with future knowledge) when he ended up back in Zeal as an adult, even joining the heroes (if you let him) — he did in hopes of getting her back. At the end of the game, he's still looking. In the sequel, it's Serge who eventually finds her and frees her from the darkness beyond time, causing her to apparently be reborn in our world, where Janus will likely never find her. In the DS Remake, Schala herself tells Magus to give up his quest to save her for his own good. She then promptly teleports the crew back into their own times and sends her brother off. Magus is left bewildered over his purpose, leaving his memories erased in the end.
Inverted with Akihiko Sanada. Instead of causing him to sink into despair, the death of his sister Miki spurred him on to fight harder to protect others — or, in his own words, to "become strong enough to do what is right".
Persona 3 Portable puts a very different spin on this if you play as a female main character. Akihiko is motivated to become stronger not simply to save others, but to avoid feeling the pain of being powerless to save someone who is precious to him. His social link halts when he senses the heroine is becoming too important to him, because as he later explains after some character development, it was easier to not let things become too important than to risk losing them. But after said character development, his motivation shifts from pain avoidance to a true desire to protect the people he cares about.
Played with in Persona 4. Nanako's death inspires the party to attempt to get revenge on Taro Nametame, turning their backs on their normally cheery, happy-go-lucky attitude towards the investigation. If the party lets Nanako's death get the better of them, she stays dead and the player gets the bad ending.
Persona 2 has a bit of this around Joker, who accuses Tatsuya of killing their 'big sis'. The 'big sis' is actually Maya Amano, who's been there the whole time. She actually escaped the fire. Oh, and Tatsuya was the one who wanted to SAVE her. Hell, it has a LOT of this with Tatsuya. When Maya DOES die, Tatsuya fucks up an entire WORLD because of it. And then he has to remember everything to keep her from dying again. Sucks to be him, right?
Micaiah has a dead king, Pelleas. Who she killed. In order to free their country from the Deal with the Devil he made. Except it turns out the king's sacrifice is useless. You can subvert this in following playthroughs and get him to live, though.
Tiltyu and Blume are a variation; he was unable to prevent her death from a broken heart through his wife's emotional and physical abuses, but on the other hand he didn't even try since it'd mean he was siding with someone considered a traitor by his people. Tiltyu's children harshly call him out.
Ethlyn and Quan's death becomes a Cynicism Catalyst to Sigurd after Thracia's massacre of Leonster's troops in the Yied Desert.
The Legend of Zelda: The Wind Waker features this trope. Link starts out on his adventure in order to rescue his sister, who's been kidnapped by a gigantic bird which ends up being Ganondorf's pet. It should be noted that this Link is a major case of a Knight Templar Big Brother, which causes him to react to the kidnapping of his sister nearly the same way a "regular person" would react to her death.
Welkin's little sister Isara is shot down completely out of nowhere, just as she was about to befriend Rosie, who had been racist towards her the entire game. In fact, oddly enough, he seems to be the least affected by it all. If anything, it's Rosie who was the most devastated, considering her tear-jerking funeral song, not to mention that she visits her grave yearly, unlike a certain brother. At least he named his daughter after her.
Cynicism Catalyst is Inverted for Rosie, as Isara's death is what finally gets her to stop being a cynical racist and become a much more likable character.
Ragna the Bloodedge, the protagonist of the BlazBlue series seems to have one of these dead little sisters until it's revealed at the end of the second game that she's not only quite alive, but the de facto ruler of the game's Crapsack World and the real Big Bad. A subversion, huh?
Several of Hawke's companions have their own Cynicism Catalyst. Aveline has her husband Wesley, whom either she or Hawke kills in the prologue to save him from the darkspawn taint.
Anders has Karl, his ex-lover, who was made Tranquil by the Templars.
Sebastian has his entire family, who were murdered by hired thugs and eventually his mentor Grand Cleric Elthina, whose murder reawakens his lust for vengeance.
Varric has his older brother Bartrand, who betrays him and whom he's eventually forced to kill or send to a sanitarium.
Merrill eventually has her mentor, Keeper Marethari, dead. Keeper Marethari dies protecting her, as well as potentially her whole clan.
Knight-Commander Meredith, the closest thing the game has to a main villain, has a textbook dead sister as part of her backstory - her mage sister was possessed by a demon who killed their parents and wiped out their village, leading her to become the most fanatical Templar yet seen.
In Fallout: New Vegas, Raul Tejada's little sister Rafaela was killed (and likely worse) by raiders while trying to scavenge for supplies for her brother (then undergoing radiation sickness/ghoulification) centuries ago. Later on in his life he had a Replacement Goldfish that was also killed. However the player, through talking with him and taking him to see various other NPCs can encourage him to pick up his guns and become a Vaquero once again. Young female Couriers might possibly serve as another substitute for Rafaela, especially if they're Hispanic.
The sale of Cold Sniper Boone's wife into slavery, forcing him to Mercy Kill her, at first appears to be the catalyst. However, his descent began well before that, when his batallion was ordered to massacre the Great Khans at Bitter Springs.
Tekken 6, Miguel's reason to join the King of Iron Fist Tournament is to avenge his sister, who's killed by Jin Kazama's bombers in the intro.
In Lusternia, the death of Amberle drives Meridian to spearhead the war against the Soulless Gods. Doubling the woe, Amberle is both his dead little sister and dead Love Interest as the Gods have no taboo against incest, being sterile. His reaction to his failure to protect her is gut-wrenching.
Meridian was the most changed of us all, I think, with the loss of Amberle. He became hard and spent much of his time with the Second Circle, seeking battles wherever he could. The hamadhi said his spirit would heal in time. It was heartbreaking seeing him wandering the beaches and staring out into the oceans, whispering Amberle's name over and over.
Natasha from Rusty Hearts is in the fight against Vlad because her brother was lost in an attack.
Artina for Valvatorez in Disgaea 4. However, rather than disillusioning him and driving him to cynicism, Artina's death (and his failure to take him promise to protect her seriously) instead drilled into him a notion that vows should never, ever be broken.
In Fable II, your older sister is killed in the prologue. Theresa uses this to motivate you to complete the plot of the game.
In Dead Rising 2, Stacey mentions that she had a sister who was bitten by a zombie and had to rely on Zombrex to stay alive. She eventually willingly stopped taking Zombrex and turned into a zombie. This is why Stacey is so dedicated to her cause.
The big bad in Duel Savior Destiny has a dead little sister serving as his motivation, though you don't find out about it until the very last route. He believes the world is so unfair that even if he fails to remake the world as intended he would still be satisfied with its outright destruction.
In Bioshock 2, the Alpha series Big Daddies were driven mad with grief by the deaths of their bonded little sister, as they saw the girls as their own daughters.
In Knights of the Old Republic, Carth Onasi's mentor Saul Karath abruptly turned on the Republic and joined Revan and Malak, and his first act on their behalf was to bomb Telos IV (Carth's homeworld) so hard the surface became unlivable. The betrayal, combined with the loss of his wife and son as well the fact that Karath hinted at his own turn beforehand but Carth didn't believe him, are the direct cause of Carth's trust issues.
The Mandalorian Wars are implied to be this for Revan, Malak, and many of the Jedi that went to war with them: they either believed saving the Republic required greater sacrifice than devotion to the Jedi ideals allowed for, or they were swayed by the Dark Side power they encountered during their battles.
Shepard's temporary death is apparently this for Garrus in Mass Effect 2. He's always been a Cowboy Cop, but it's the attack on the Normandy that drives him to quit C-Sec and become an Unscrupulous Hero as the bounty hunter, Archangel.
The Wotch: It is strongly implied that Miranda West's distance is because she blames herself for her friends' deaths.
Roy Greenhilt has a dead little brother named Eric. It's implied that Eugene was responsible, though Roy blames himself to a certain degree. His comment on Eric's love of music and potential future as a bard may also provide insight on his relationship with Elan.
Redcloak, the Anti-Villain, is revealed to have a dead little sister in the prequel book Start of Darkness, and at the end of the book, he's forced to kill his brother too.
Darby has the older brother version in TRU Life Adventures. Watching how others got hypocritical in response had more of an impact than the actual death, though.
In Errant Story, Ian set off on his quest to find the elven gods because his older sister was dying and he wanted to find a way to heal her. When he achieves godlike power and returns home to find that she died while he was away, he snaps and blows up a few cities
In Picatrix, Samael is motivated to exact revenge on the angel of death who took the soul of his twin sister.
In Powerpuff Girls Doujinshi, Dexter seems to be collecting these. First of all he's got the haunting death of Dee Dee, his dead sister (ironically a dead big sister) hanging over him. Then, not long after, he develops a secondary complex involving his guilt over Mandark's death in light of Mandark's own little sister promptly moving to Dexter's school after the loss of her sibling. One way or another, he’s suffering a lot of angst these days.
In El Goonish Shive, Susan has had two of these; the first was the aftermath of her father cheating on her mother and the second was when she had to kill the aberration.
Marsh seems to regard his little sister Tina as dead, even though she is standing right in front of him, because her memories were apparently altered by the experiment.
Later in the story, Marsh finds out that his favorite cousin is now Ret Gone due to the same experiment, leading to a Heroic BSOD.
On We're Alive, Todd's death at the hands of the zombies is Lizzy's main reason for wanting to kill every zombie she sees.
After Samantha's Death, Datu spends a lot of time being generally depressed and hopeless. During The War and its aftermath he is completely convinced that everyone is going to die and begins leading some of the other Tower members in prayer rather than trying to help fend off the Mallers/zombies/fire. It isn't until Michael, Pegs and Kelly return from the Colony with Samantha's daughter, Hope, that he really gets better.
In Redvs Blue, Agent Washington was shown in the Project Freelancer sections to have been a fairly idealistic and warm guy. However, having an AI go mad inside his head and show him all that had happened to the Alpha AI and the Director turned him into the bitter, cynical man he is in the present.
In Justice League "A Better World", the Justice Lords are revealed to have started falling off the slippery slope after their Flash was murdered.
When Scarface murdered Dreamer, the youngest daughter of Fox and Vixen, in The Animals of Farthing Wood, this led not just to the feud between the red and blue foxes, but also resulted in Bold, their eldest, attempting to hunt him down when he got old enough.
Shadow Raiders. Graveheart's younger brother perished in a raid Graveheart was leading against Planet Fire for energy; this explicitly caused him to renounce his position in the elite Quarriors and become a simple miner instead, and is implied to be the reason why he is so keen on the idea of peaceful trading replacing the former raid-based interactions between the worlds.
In Avatar: The Last Airbender, Iroh and his son Lu Ten could be considered an inversion (similar to Dumbledore and Ariana). Iroh was one of the Fire Nation's most feared generals until Lu Ten died in his legendary siege of Ba Sing Se, at which point Iroh abandoned the siege and had his experience in the spirit world. By the time the show actually starts, he puts the "cool" in Cool Old Guy, is the grandmaster of a secret, international society of fellow awesome old people, and is clearly only sticking with the Fire Nation army so he can give his nephew Zuko an alternate role model to Ozai.
John Fitzgerald Kennedy had his dead older brother Joseph, who died in World War II. Both he and Joseph Jr. were dead older brothers to Bobby and Ted, and sadly, JFK, RFK, and Joe Jr. all were dead older brothers to Ted, the only one who lived a full life.
JFK's two sons, Patrick (dead two days after his birth) and John Jr. (dead in a plane crash alongside his wife and sister-in-law) are dead younger brothers to his only surviving child, his daughter Caroline. Who also has a dead older sister in Arabella (a stillborn child).
The Kennedy Family's involvement in the Special Olympics is inspired by (or perhaps penance for) the fate of JFK's sister Rosemary, who was lobotomized and then kept locked in an asylum as a young adult because Joseph Kennedy Sr. was flimflammed into thinking it was a good way to deal with a willful daughter by celebrity lobotomist Walter Freeman.
Samuel Clemens lost his younger brother Henry in a boiler explosion on the steamboat that he piloted, and was guilt-ridden about it for the rest of his life.
Akiyuki Nosaka, author of Grave of the Fireflies, wrote it as an apology to his little sister who died of malnutrition in war torn Japan during WWII. Internet rumour has it that she didn't die of malnutrition and that he simply lost her one day and never saw her again. The book (and subsequent anime film) were ways of convincing himself of this. Japan's records of the time are terrible at best and it's most likely that the story was crossed with one of someone else.
The Greek tycoon Aristotle Onassis and his daughter/heiress Christina had her son and her older brother died, respectively: Alexandre Onassis Livanos, who died in a plane crash at age 25 (which is a favorite topic among Conspiracy Theorists). Both of his parents crossed the Despair Event Horizon at that: mother Athena Mary Livanos ("Tina") commited suicide, Aristoteles's already decaying health plummeted and he died few months later. Christina outlived everyone for more than a decade, but she didn't have it much easier either.
Philip K. Dick's twin sister who died when the two were only five weeks old. Being raised as a child with this knowledge (his mother allegedly claimed that the wrong child had died during an argument) the loss haunted PKD throughout his life. The figure of the mysterious, dark-haired and unattainable woman that is prominent in so many of his works (especially "Flow My Tears, the Police Said") is said to based on PKD's imaginings of what his sister would have been like had she lived.
As told in Boy: Tales of Childhood, the loss of Roald Dahl's older sister Astri drove his father to Death by Despair when he fell ill with pneumonia.
Wyatt Earp vendetta against The Cowboys, following his brother Virgil's permanent injury and Morgan's death. It's known for being retold in the film Tombstone.
Back in 2004, UFC middleweight Vitor Belfort's sister Priscila was abducted in Brazil, and for three years he used his fights as a soapbox from which to tell fans about this and solicit information and help, the distraction due to this contributed to his losses in this time. Unfortunately in 2007 a woman ended up confessing to her murder, though the Belforts didn't initially believe her (fearing rather the possibility of her covering for someone else); nevertheless, it was only after this that his career turned around — and at his UFC 142: RIO, her face was on his team banner.