Tetsuya Tsurugi from Mazinger Z and Great Mazinger is serious, grim-looking and moody, and he seldom smiles. So when he grins, everyone freaks out and dons Oh Crap stares. Mainly Warrior Monsters, since it usually means they are about of dying horribly and painfully.
Inverted with Death — if he starts acting in character, you know you're in some serious shit. He does occasionally put on his old scary voice just to scare his staff into paying attention, and is even more likely to treat the most dire of circumstances (Asura's resurrection, Kid's abduction) casually, even jokingly.
Also played straight: if Black☆Star is not yelling and Death The Kid is not OCD'ing over symmetry, prepare for an asskicking. Kid's an interesting example because the occasions he faces disorder and doesn't have a fit over it tend to be when he instead fixes on another inherent characteristic, that of him being a Shinigami (e.g Mosquito, minor point in his second fight with Black☆Star).
Shunsui (or Syunsui) Kyoraku never loses his temper, and his general demeanor never really elevates beyond "mildly concerned"—even when fighting his mentor who is implied to be thousands of years older than he is. However, when his Heterosexual Life Partner appeared to have been killed, he lost it. For extra emphasis, even in the context of that story arc, his reaction was pretty extreme.
Chizuru Honshou is the local Genki Girl and Plucky Comic Relief. She has only cried twice in canon,: the first happened when she and others were subjected to Body Horror and forced to attack Tatsuki and Orihime thanks to Numb Chandelier, and the other was during her Heroic BSOD when Aizen was chasing her, Tatsuki, Keigo, Mizuiro and Mahana through Karakura Town.
When Ichigo decides to murder Tsukishima (despite never having killed anything other than hollows at this point) on the off chance it will reverse his Fullbring's effect on his friends and family, you know he's pissed.
The usually cool-headed Byakuya completely loses his composure when As Nodt steals his bankai, therefore proving how utterly screwed the Shinigami are.
In an episode of Samurai Pizza Cats, space-cadet Emperor Fred (who normally communicates by saying "Fuh-red!" and scat-singing) catches a nasty cold, and apparently upgrades from The Unintelligible to Talkative Loon ("This is to certify that kung pao chicken containing MSG may cause your BMW to have a headache...") This leads Al Dente to conclude that the emperor is very sick.
Pippin, the Gentle Giant of the Band of the Hawks in Berserk, never speaks and is never seen with eyes open. He only opens his eyes and speaks for the first (and last) time when the world goes to hell around him during the Eclipse.
One episode of the Ranma ½ anime has Happōsai, the resident Dirty Old Man, acting extremely despondantly and unlike himself. It culminates when Female!Ranma is forced by the fathers to put on a swimsuit and give the Old Master a show in order to raise his spirits... and he just tells her to Please Put Some Clothes On. At this point, everybody know there's something very wrong with Happōsai.
Trigun. Vash's reaction to Monev the Gale's wholesale slaughter of a small town in the anime is a definite example of this. Vash is usually a goofball and kind to the point of preferring to be injured himself rather than hurt anyone else, even when people are actively trying to kill him, but after seeing what happened to the town he puts a gun to Monev's head gets this close to just blowing his head off.
In One Piece, as a result of massive Despair Event Horizon, Luffy becomes so depressed that he admits his own weakness and renounces his worthiness for the title of the Pirate King.
Played for Laughs in an earlier moment, when Nami gave treasure to Lola. Luffy and Usopp were shocked, and actually shouted "A STORM IS COMING !" !
Arguably any time that Luffy stops joking around and being a total moron it's clear that shit is about to go down.
At one point in the Alabasta arc, Vivi says three words to Crocodile: "I'll Kill You!". Mind you, this is coming from a young princess who is such a Nice Girl that she can't stand the idea of a single person dying in a war.
Luffy actually uses this on purpose to relay a secret message to his crew after they've been separated to meet up in Sabaody after two years.
In Tsubasa: RESERVoir CHRoNiCLE, it's clear that Fay's mental state has taken a turn for the worse not because he grows his hair out after losing his eye and takes on a generally more gloomy disposition, but it's because he drops the cutesy nicknames and actually calls Kurogane by his name. Later on when he starts using them again it's a huge relief to everyone since it indicates that he's getting better.
In Bakuman。, Hiramaru, infuriated over the reasoning behind putting Detective Trap on hiatus until Mashiro graduates, storms off to work on his manga.
Eiji Nizuma is a manga enthusiast who reads everything in Jump,especially the main characters' work, since they're his rivals. When he says he isn't reading Tanto, it's proof of how strongly he believes that it's inferior to their work and they are not living up to their potential by working on it.
Shinryaku! Ika Musume: Similar to the Bleach and Negima examples — when Chizuru opens her eyes, you're screwed.
Except for the one time she was trying to be friendly instead of intimidating. And it was adorable.
There is just ONE time in which Goku from Dragon Ball refused a meal. When he sensed that his best friend Krillin was in danger and rushed to help him. It was too late: Krillin was already dead.
As for Dragon Ball Z, Vegeta was the Big Bad of the series during the first story arc; one arc later, he breaks down, reveals his dark past, and cries during the Frieza Saga just as Goku arrives to fight Frieza.
Another Vegeta example involves him blowing himself up in order to destroy Majin Buu, save the world, and express his love for his wife and son.
The few times Shouma does not attempt to solve problems via words, things have got really bad. Specially the last one.
Similarly, his penguin #2, a Big EaterExtreme Omnivore, only once decided to share his meal with his "sister" #3. She refused it and left him all dejected — a foreshadowing of her and Himari leaving the Takakura family home.
This is a general (but important) plot point in Darker Than Black. Contractors are completely emotionless and self-serving, so when some of them aren't, people always make note of it. Likewise, Dolls are so completely empty that they won't even eat without proper programming. At one point, one uses her specter to call for help, which is about the same as your cell phone calling to tell your friend you're getting mugged.
In the season 1 finale of Code Geass, the typically whimsical Lloyd freaks out when he notices Nina ready to detonate a sakuradite bomb. Rakshata, knowing full well he's serious by his sudden change in demeanor, calls for a ceasefire.
In Katekyo Hitman Reborn!, Reborn always pushes Tsuna to succeed in any given situation and never gives him a break because he knows that Tsuna has the potential to pull it off. So it's a huge shock to Tsuna when Reborn tells him that he has no chance of defeating the strongest member of the Vindice.
Once in Axis Powers Hetalia, Germany joined Japan on a diet and gave up beer. This leaves various Germans completely stunned and Prussia is nearly brought to tears out of fear.
Kyoya Otori is a very cold, calculating, selfish man who never does anything that he can't gain from (at least, nothing that he'll admit to.) So when he blows up in Tamaki's father's face near the end of the manga and delivers an angry Reason You Suck Speech to him for forcibly wresting control of the Suou family businesses from Grandmother Suou and dashing Tamaki's hopes of someday reconciling his entire family in the process, despite there being nothing to gain and everything to lose from it, it comes off as a serious Crowning Moment of Awesome for him.
In 3-gatsu no Lion, the normally meek Rei eventually becomes irritated over Nikaidou's taped lecture over his MHK Cup loss and is vocal about it as he shouts back at the screen. Someji and Momo's reactions play it off like a joke as they look in amazement and surprise over Rei actually getting angry. However, Hina, in a slightly more serious moment, is happy to see a side of Rei that she never gets to see.
In Bakemonogatari, in Hanekawa's arc, when told that she knows everything, she responds "I don't know everything, I don't know anything." By comparison, her catch phrase is "I don't know everything, I just know what I know."
Played for Laughs in Nisemonogatari. Araragi is so freaked out by seeing his tomboyish little sister Karen wear a skirt that he assumes she was bullied into it.
In the first arc, Rena and Mion or so we're lead to believe act... oddly, prompting Keiichi to become defensive, ignore them outright, and to even carry a weapon around. This in itself triggers a very serious reaction from Mion and Rena, who believe what's happening to him is what happened to Satoshi a year prior- just before he vanished.
When Satoko (aka the Master of Traps) doesn't respond well (or at all) to her friends' playful jokes, it means it's her turn tobreak.
If Rena is serious, it has two possible meanings: she's snapped from Hate Plague and is about to kill (or has already killed) someone, or one of her friends is in serious danger.
If Mion's genkiness goes away for a while, she's either acting more girly (read: impersonating her twin sister) to get closer to Keiichi, or if it's played for horror, it's not her at all; it's Shion instead. And, like Rena above, she becomes very serious when her friends' lives are in danger, or when attending family meetings.
Throughout the Endless Eight arc, Yuki is frequently seen looking mildly bored or sad, which is pretty much the equivalent of a Heroic BSOD for her from being trapped in a Groundhog Day Loop for almost 600 years.
In the story "Snowy Mountain Syndrome," when the Brigade gets lost on a mountain and finds a mysterious mansion, Yuki is even more listless and detached than normal, not saying a single word to anyone and barely nibbling her food. When pressed, we find out her link to the Data Overmind has been cut, and she has no idea how. So this is her freaking out.
Later during Snowy Mountain Syndrome, Yuki actually faints, which shocks Kyon, Koizumi, and Mikuru so much they can't even move to catch her when she falls. Thankfully, Haruhi (who is unaware that Yuki is a Physical God in all but name) isn't quite so stunned, and is there to grab her before she hits the ground.
Mako is typically coolheaded at her most energetic and lethargic and lazy at worst. When she hears about her grandmother collapsing, she becomes especially determined to reach the hospital as soon as possible, even considering swimming an impossible distance if necessary.
Katyusha is quite arrogant, and enjoys sitting on the shoulders of Nonna to seem taller than everyone else because of her short height. When she's defeated by Oarai, she gets off Nonna's shoulders and shakes Miho's hand, something she had refused to do earlier, to congratulate them.
In the Little Army prequel manga, Miho, upset by Maho's aloof behavior after admitting to having shot an enemy flag tank when it went to rescue one of hers, questions her mother on whether it was necessary, despite her timidity and unwillingness to call her own mother out. Her mother shrugs this off, but Maho makes note of this and later comes to speak with Miho privately to apologize and tell her to pursue her own style of tankery.
Momo typically alternates between being relatively calm and getting comically angry over things like missing or being called "Momo-chan". On some occasions, though, she seems genuinely upset, such as when the team doesn't care whether or believe they can win, especially considering the school will be shut down if they don't win the tournament.
Miho is generally a polite girl who can't find it in her to say anything bad about other people, even the Jerkasses. When Emi begins saying she hates Miho's sister despite never having gotten to know her, Miho loses her temper and, in her anger, declares she hates Emi. Miho's friends are shocked at how Miho got angry, and Sakuyo notes that it's rare for Miho to get angry.
During Urusei Yatsura, Ataru usually has either a goofy look or a perverted look on his face. When he's caught looking serious, things just got real. It's even pointed-out during the Anime itself.
Almost everyone in the Marvelverse knows that letting Dr. Bruce Banner get angry is a one-way ticket to Serious Business. And even without the gamma transformations, an angry Bruce Banner is scary. His very first "Hulk" episode occurred long before he was exposed to gamma radiation. During it, he killed his abusive murderous father.
Skalman from Bamse, a Swedish comic series, almost never showed emotion, and always obeyed a strict schedule. When he stopped obeying that schedule for a bit, or snapped at his friends, you knew it was serious.
In the recent comic book adaptation of Darkwing Duck, the Liquidator, who has the Verbal Tic of speaking in ad slogans and bogus claims, suddenly drops it just long enough to warn someone about Quackerjack's Berserk Button. Which turned out to be Serious Business indeed.
Death Of The Family: Joker has always used Joker Venom, which kills a person and leaves them with the creepiest grin on their face. But this time, his venom kills a person, and leaves them with a frown on their face. Something is wrong...
The Joker has always had a fondness for jokes, tricks, and gags in his various schemes and murders, but in A Death In The Family he forgoes his usual methods and simply opts to beat Robin (Jason Todd) half to death with a crobar and let a bomb finish the job.
Some writers claim that part of the reason Spidey quips mid-battle is because his enhanced nerve conduction velocity (reflexes and spider-sense) actually allows him to think at superhuman speeds... which means that to him, the world is moving in slow motion during a fight, and he fills in the extra time by making jokes. If he's not making them, not only is it frightening that he's strong and angry, it's frightening that he's dedicating 100% of his genius intellect and enhanced processing power to deciding how he's going to hurt you in the most personally satisfying manner possible.
A theory put forward by Stan Lee himself is that Spidey is making jokes to cover up that he actually is terrified, so the bigger the danger, the lamer the jokes. So when he stops it usually means that no matter how terrifying and dangerous you are, he is not buying it anymore. Now all he feels is that he really wants to beat you unconscious.
Rorschach of Watchmen is gruff, insulting, and arrogant most of the time, and also doesn't usually use pronouns or proper names. When he says, "Daniel, I apologize. I know it's difficult being my friend," you know he's being dead serious.
When Dan/Nite Owl finds out that his friend and mentor, Hollis Mason/the original Nite Owl was beaten to death by members of a gang, he starts beating the ever-living crap out of a gang member, to get information about the murder. Even though Nite Owl has no aversion to violence, the raw viciousness makes Rorschach of all people stop him. (Although his rationale is to tell Dan, "Not in front of the public.")
Any time that the Pre CrisisLex Luthor, the version who used to be Superboy's friend and a pretty nice guy, would have a Pet the Dog moment, it represented his earlier decent nature showing through, and (rightly or wrongly), it gave Supes hope that someday he might come back to the side of the angels. One of the very last Pre Crisis stories, "The Ghost of Superman Future,'' indicates that in at least one possible future, Lex did eventually reform and they became friends again in their old age. It was by Elliot S! Maggin, who was very fond of Luthor. He later wrote a short story along similar lines called "Luthor's Gift."
In the 3rd book of Bone, while the world slowly crumbles due to the Rat Creatures and Thorn learning she is a princess, Grandma Ben, whose eyes are always closed, opens them for a split-second when she finds out that she has partially doomed the Valley by not telling Thorn that she is a princess.
Deadpool, the fourth-wall breakingWild Card to end all wild cards, has his speech bubbles and thought rectangles shaded yellow, to show that he's the one guy in the entire comicverse who knows he's in the comicverse and is perfectly okay with it. On the rare occasions where his speech bubbles go to the normal white shading, meaning he's taking things seriously, you know it's significant. The plot of Deadpool Kills The Marvel Universe involves the yellow voice getting somehow killed... and the red voice replacing it. Let's just say it doesn't go well for the world.
Scootaloo turning down an offer to hang out with Rainbow Dash is so upsetting that RD has to tell her friends about it. (Whether she's worried for Scoot, is just nursing her bruised ego, or both is uncertain.)
In Calvin And Hobbes, as Calvin is lying sick in bed, his mom tells him she's going to call the doctor, and ends with telling him it's Saturday, so he won't miss school. He responds with a weak, "I know." Since Calvin had, earlier, reacted with horror at the prospect of missing some of his time off school due to a lesser illness, his mother is sent racing to the phone. It must be serious.
In the final week of dailies of US Acres, Lovable Coward Wade achieves peace with the world... sending Orson, Roy, and Booker away screaming in terror.
In Fan-made Axis Powers Hetalia video game, Heta Oni, at one point, Italy starts acting seriously OoC, and then he locks everyone up in a cell so they won't 'get in his way'.
In Undocumented Features, Azalynn, who's been shown to be extremely forgiving, finds herself holding a grudge against Liza for calling the Psi Corps on Devlin, even when everyone else has forgiven her. She is extremely shocked when she realizes how spiritually off-balance she is.
Exaggerated in I Cannot Tell a Lie when England is unable to properly insult France at a meeting (it was because of a spell). Almost all the characters reacted to this by passing out, going catatonic, or panicking and screaming (their theories for this OoC moment include the apocalypse and an alien invasion). Oddly, the only person to remain calm is America, who just thinks England's sick.
In Out of Time, when Kenshin is mystified by the burnt soup Kaoru made and says it tastes bad, Yahiko asks him, "Who are you?"
Sano: Wow, guys, check it out; the Weasel's gone speechless... Megumi: Please don't say that. I think I read somewhere that that's a sign of the impending Apocalypse.
When Nepeta drops her cat puns and other typing quirks in Herding Cats, that means she's really upset.
In From Shizunes Perspective, midway through the fic, Shizune notes that Misha is chewing her lip like she does during tests she expects to fail, and is not snarking at her like she usually does. Misha claims that it's out of sensitivity toward Shizune, who is upset over Emi not responding to her text messages, but the truth is that Misha and Hisao have a Secret Relationship, and are worried about how Shizune will react.
In Things We Don't Tell Humans, Prowl has a loud, public, and surprisingly violent breakdown when he finds out who died in Transformers. And we learn to pay very close attention to out-of-character moments from Megatron (both in the present and in the flashback arcs) and from Mikayla.
While he's generally a goofball, Cruise Control turns dead serious for a few seconds to tell Apple Bloom that older siblings always care for their younger siblings. It's later revealed that that side of him is his real personality, his doofus side being an act.
Trixie drops her Third-Person Person act a few times, perplexing Twilight. When she finally gets around calling Trixie out on it, she discovers black psyche-locks on her; in other words, she's hiding a great secret and sorrow, and has no intention of revealing the reason behind it.
My Little Avengers: You know Rainbow Dash has become a Thor fangirl when she's so excited about attending a party in his honor that she forgets the Wonderbolts are going to be there too. Pinkie and Big Mac are left rather stunned.
Hivefled: Equius had been rapidly losing his respect for Gamzee as Gamzee slipped further into his rages, to the point that he was willing to insult him to his face and strife without letting him win. When their conflict indirectly leads to Nepeta dumping Equius and he screams at Gamzee that he intends to "wring your scrawny neck", he's over the edge.
Silver: You heard the boy! Get this blasted heap turned 'round!
In An Extremely Goofy Movie, Max is convinced that he wants to transfer schools after being defeated by his own dad at his best event, because there's "only room for one Goof." PJ is devastated at the news—temporarily relapsing to the insecure and worrisome personality he'd just broken out of— and Beret Girl tells Max that he can't admit defeat, but nothing helps... until Bobby, the Plucky Comic Relief, in a dead-serious, emotionally-charged tone, gives Max a Rousing Speech.
Films — Live-Action
When Silent Bob speaks, you listen. Though this tendency begins to annoy Jay after a while. This tradition is itself subverted in Clerks II, when Bob's cue to speak arrives and he can't think of anything to say...
In the final scene of Penn & Teller Get Killed, Teller (who has never spoken to this point), finally breaks his silence to ask what the hell is going on.
In Galaxy Quest, Classically Trained Extra Alexander Dane hates being known as a character from a sci-fi series, and hates his Catch Phrase even more, spending most of the movie trying to get out of saying it, or saying it in monotone. However, when an alien who's always looked up to Alex's character is shot and killed, Alexander says, sincerely, "Quellek... by Grabthar's hammer... by the Sons of Warvan... you shall be... avenged" before opening a can of whoop-ass on the bad aliens.
Running Scared (1986)
A humorous version can be found when the two main characters call for backup. They come out of the building without their pants (having had to give them to the Big Bad of the film), only to find that a huge number of cops — including the SWAT units — have shown up to help.
Danny Costanzo: I said "one backup"! One! Cop:(trying not to laugh) You never called for backup before! We... (barely keeping from laughing)We thought that it was a riot...
There's another: When Danny Costanzo (Billy Crystal) soon-to-be-ex gets kidnapped by the Big Bad, Danny (who up until this point has not slowed down the wisecracks for a second) get's a call from the crook letting him know his girl's in trouble:
Danny Costanzo:(in a dangerous, low tone) You hurt her, you'll never be dead enough.
In the Mary-Kate and Ashley Olsen movie It Takes Two (a rip-off of The Parent Trap), the girly girl of the Tomboy and Girly Girl duo is trying her first sloppy joe. After doing so, she claims it's her favorite, "for a durn good reason." After a beat, the camp counselor turns to the girl and asks "Did you just say 'durn?'" Then quickly checks the girl's temperature, clearly fearing an illness.
In the film of Harry Potter and the Deathly Hallows, Harry is running around looking for the diadem. Luna is trying to tell him he needs to ask a ghost, but Harry won't listen. Luna, usually the gentle Cloudcuckoolander, shouts "HARRY POTTER! YOU LISTEN TO ME RIGHT NOW!" Harry, suitably shocked, turns around and listens.
In the fifth movie, when Hermione observes that it's kind of exciting breaking the rules, Ron demands "Who are you and what have you done with Hermione Granger?"
In one of the Dirty Harry films, the title character is tipped off to a robbery in the coffee shop that is his usual haunt by the waitress breaking a years-long routine and dumping a large amount of sugar into his coffee.
Marianne is shown to never swear. She constantly uses euphemisms like "rhymes-with-witch", and other gosh-dang-it-to-heck-isms. But when she hears the rumor that Olive gave Marianne's boyfriend Micah chlamydia, Marianne completely loses it, and yells, even screams "That... that BITCH!"
Also, Marianne is shown to be a bit snide, condescending, and utterly dedicated to attempting to correct other's supposed sins, but she does it without being out-and-out confrontational. But after she snaps, she full on slaps Olive across the face. Which is most decidedly not a typical Christian value.
In Sherlock Holmes A Game Of Shadows, Watson deduces that something serious is going on from the fact that Mycroft is missing an appointment at the Diogenes Club, especially since his favorite dish, potted shrimp, is on the menu that night.
Unforgiven: When William Munny, who'd been sober for many years, starts downing that bottle of whiskey before going after Bill Daggett, you know things are about to get serious as a heart attack.
In Serenity when the crew land on Haven and find that it's been razed, Mal loses it. After telling his crew to strap bodies to the front of the ship, threatening to kill any of his crew that gets in his way and shooting dead an Alliance soldier trying to surrender, the crew know that it's all just hit the fan.
Manderlay (the sequel to Lars Von Trier's Dogville) features a double-dose of this towards the end. After the freed slaves celebrate their first harvest, they discover that the money they worked so hard to get has been stolen- and it could have only been done with the help of one of the ex-slaves. Following a massive off-screen riot that gets two people killed, Grace finally arrives on the scene to ask questions: Wilhelm, the man usually relied upon to explain things, is too shell-shocked to speak of what happened. This leaves Mark holding the exsposition ball; for once, he doesn't bother dithering around with longwinded tangents, and provides a straightforward explanation.
A small, but powerful moment in Star Trek VI: The Undiscovered Country. After apparently firing on a Klingon battlecruiser carrying the Klingon Chancellor on a diplomatic mission, the battlecruiser recovers, rights itself, and prepares to retaliate on the unshielded Enterprise. Kirk watches this for a full three seconds in silent, slacked-jawed horror. He doesn't raise shields, or order evasive maneuvers, or any of the other things that fans expect him to do; he just watches. . .and then he surrenders. This is the first time in the history of Star Trek that Kirk is ever seen to falter in the command chair, and it's terrifying.
Another one in the same movie by Spock, the paragon of emotionless logic and reason, who very angrily smacks a phaser from the hand of his protegé, Valeris, who had just been exposed as a conspirator in Gorkon's assassination. He later uses the Vulcan Mind Meld to try and pry the identities and plans of the conspirators, which ends up becoming, based on the reaction of the receiving party, dangerously close to Mind Rape.
Mac The Bartender is also The Quiet One. The seriousness of any particular book is proportional to the number of words that he says. A complete sentence or two is enough to scare Dresden. In ''Changes'' he goes on for a good sized paragraph.
Also, in Blood Rites, Lieutenant Murphy meets Harry's mentor, Ebenezer McCoy. As they are on a hunt for vampires in Chicago, Murphy tells him (rudely) to get out of the driver's seat. Harry tells him to do it, slipping in the word "sir." Murphy drops everything she's carrying, mainly because hearing the anti-authority Dresden using the word "sir" something that you only hear once. Also justified, as Ebenezer is the only one to whom Harry will apply an honorific. Being Harry's Obi Wan has its perks.
In Dead Beat, Harry asks Bob about Kemmler, the author of a book that the visiting group of Necromancers are all hot and bothered about. Bob has a minor freak-out, and tells Harry that Kemmler was straight up, capital-E Evil. This immediately catches Harry's attention, mainly because Bob's view on morality is... sketchyat best.
Toot-toot the dewdrop faerie is normally fearless and a ravenous junk-food addict. When Toot tells Harry to run, it's serious; when he tells Harry to forget the doughnut and run, it's dreadfully-so.
To Kill A Mockingbird is full of these: Scout notes the only time she ever heard Atticus raise his voice (when he's defending his parenting style to Aunt Alexandra) and the only time she ever heard him call something a sin (to kill a mockingbird). Jem decides to follow Atticus the night the mob threatens him outside the jail because Atticus took his car instead of walking as usual. Scout and Jem are shocked at Tom Robinson's trial when Atticus takes off his jacket and loosens his tie, because they've never seen him do that during the day. Scout knows that Aunt Alexandra is seriously shaken when the children have been attacked at the end, because she brings Scout her overalls to put on, after spending the entire book trying to get her to stop wearing them. And, of course, there's Boo Radley leaving his house for the only time in living memory in order to protect them from Bob Ewell.
In the earlier books, moments when Hermione was in favor of breaking the rules were this.
Most notable was when Harry and Ron save Hermione from a cave troll. She saves them from getting into trouble by lying and saying she thought of going after the troll and they were only rescuing her (when really, the troll found her by chance and Harry and Ron broke the rules and went after it, instead of going to their dormitories). Not only did Hermione lie to a teacher to cover for Harry and Ron's rulebreaking (something which she refused to go along with earlier), but she used a cover story that made her out to be the rulebreaker. Harry compares the situation to Snape giving out candy.
In Prisoner of Azkaban, Dumbledore loses his temper for the first time in the series when a pack of Dementors nearly kill Harry. Hermione mentions that it was absolutely terrifying.
Sweet, motherly Molly Weasley reacts rather badly when Bellatrix tries to kill Ginny.
Molly:NOT MY DAUGHTER, YOU BITCH!
A rather terrifying example happens at the end of the first book. Who would have suspected p-p-poor s-stuttering Professor Quirrell, normally an extremely timid man, as the true mastermind behind the whole plot and a faithful servant of Voldemort? So imagine Harry's surprise when he finds Quirrell in front of the Mirror of Erised, and Quirrell promptly has Harry magically tied up in an attempt to force him to find the Philosopher's Stone.
When confronting the fake Moody in The Goblet of Fire, Harry realizes just how much of a threat Dumbledore is to the Death Eaters, as he sees for the first time that Dumbledore isn't just a harmless old man, but is a powerful and dangerous wizard capable of magic that Harry can't even pronounce.
In The Chronicles Of Narnia series, this happens in The Voyage of the Dawn Treader. When the ship is attacked by a giant sea serpent, Reepicheep yells at everyone to push the serpent off the boat rather than fight it. Since Reepicheep usually fights first and asks questions later (at one point earlier in the book he had to be restrained from challenging a dragon to single combat), this is unusual enough to startle the rest of the ship's crew into helping him.
In Roadkill, the last book of the Cal Leandros series, Robin Godfellow, aka lust incarnate, becomes monogamous. All of his friends instantly assume he must be seriously ill.
Rincewind is an inept coward who would much rather run away from most problems rather than face them head-on. In Sourcery, Rincewind challenges the most powerful source of magic on the disc with a half brick in a sock, and then holds off a swarm of eldritch abominations long enough to escape, armed with only a sock full of sand.Holy shit.
Conversed by Twoflower in The Light Fantastic, when he reasons that Rincewind's uncharacteristic lack of fear about the Red Star implies that it's not the world-ending threat most people assume it to be.
Death almost never ends his sentences with an exclamation mark, so you know he's pissed off when he shouts at the New Death for setting himself up as a ruler over mortals, in Reaper Man.
This is also invoked for Death when he speaks emphatically of the Auditors' hatred for humanity in Hogfather (represented as italics), shocking Susan.
Lets not forget Death's first major role in Mort, where he is throughout the book made to be The Stoic, and is even explained to lack the physical capability for feelings, but in the climax of the book he expresses extremely human rage, unlike ever before or after, and when Mort is at his mercy, he does a mocking, cruel Evil Laugh, which also is a completely unique expression of negative emotion — right before revealing that he decided to spare Mort and his friends after all.
Vetinari takes pride in his ability to play Sam Vimes like a fiddle and get him to do the best job imaginable... all by keeping him suitably pissed off. Vimes even tends to punch the wall outside Vetinari's office as he leaves, sometimes hard enough to require repair. Until one day Vimes departs, and Vetinari doesn't hear the telltale thump, and realizes that he might have gone too far.
The Librarian hates to be called a monkey (orangutans are apes), and will apply a great deal of physical violence to remind people when they forget this. That's why, when the Senior Wrangler calls him one in The Last Continent and gets away with his head still screwed on, the other wizards become quite concerned. There's another occasion when someone calls him a monkey, and he pats their hand comfortingly.
In A Hat Full of Sky, Rob Anybody is so worried about the hiver going after Tiffany that he starts to lose interest in hunting, fighting, and other activities typical of the Nac Mac Feegle. When he refuses a drink of Special Sheep Liniment, the other Feegles are briefly convinced he's dead.
In The Fifth Elephant, while searching for Angua, Carrot not only raises his voice when Gaspode tells him a wolf has been caught in a nearby village, but actually uses deception to acquire the animal so it can help them locate her. For straight-laced, inscrutable Carrot, that's tantamount to any other man having a full-on nervous breakdown when his girl goes missing.
In Good Omens Aziraphale the angel may no longer be completely uncorrupted by humanity, but he's still angelic enough that he's the undisputed master of Gosh Dang It to Heck!. Then, he swears. And shit just got serious.
Daur is considered the most straitlaced and disciplined of the lot. In Only In Death, he nearly hits Rawne, which is taken as a sign of the insidious effects of Hinzerhaus. In Blood Pact, when he is caught helping out in one of Rawne's scams, Hark thinks that the regiment's discipline and morale has hit a new low.
Only In Death has some more of these. Normally unflappable Mkoll gets spooked, chatty Maggs is unusually silent...
E.E. Smith's Skylark Series: The reason Dick Seaton knows the scientific knowledge he needs to save the Earth exists is because of independently-evolved legends from two worlds of a large and complex star cluster, which describe their gods stunning mortals who attack them. This is despite ten thousand years of strike-to-kill conditioning in both races. Ergo the legends must contain a grain of truth to have lasted for that long without "stunned" being changed to "killed", and the "gods" must be the Sufficiently Advanced Aliens he's looking for. He turns out to be right.
In Larry Niven's short story "Flatlander", our hero Beowulf Shaeffer has just finished doing some scans outside the spaceship. He turns to his companion:
Beowulf: Elephant, have you noticed a tendency in me to use profanity for emphasis? Elephant: No, not really. Beowulf: Well, it's goddamned radioactive out there.
In second Black Company book when Goblin doesn't way to play tricks with One-Eye as he usually does and instead of smiling and humilating his rival he actually gets provoked by him, worse, attacks him with his bare hands, everybody knows there is something wrong.
In the first chapter of World War Z, Dr. Kwang Jing-shu says he knew that something very bad was happening through a combination of this trope, Meaningful Echo, and Out-of-Character Alert. An old army comrade renowned for seeing the worst in any given situation, Dr. Gu Wen Kuei, once had a rare non-curmudgeonly moment when they were performing extremely difficult surgery in the middle of a dangerous border clash in Russia, and said to the nearly-disembowelled patient, "Don't worry, everything's going to be all right." Years later, when Jing-shu calls him about a small outbreak of unusual symptoms, Kuei, who knows what's going on, repeats the familiar reassurance, and that's when Jing-shu realizes that the outbreak is not isolated and the situation is much worse than he thought.
Marco is known for being such a fountain of snark that whenever he's serious, it's safe to assume that something pretty upsetting is going on. At one point, during a mission that involved his mother, when he was understandably preoccupied, Jake had to take him aside and tell him to start cracking stupid jokes because he was scaring the others.
Jake did the same thing to Rachel in another book when she was acting too cautious.
Commented on when Ax starts screaming at everyone to book it during an infiltration attempt:
Ax never yells. So when he does, it's usually a good idea to pay attention.
In the Dark Nest Trilogy, Luke Skywalker (whose job it is to exemplify tranquility and serenity) drops the GFFA equivalent of the F-bomb.
In Warrior Cats, Jayfeather invokes this by saying he's glad that the cranky elder Mousefur isn't acting all sweet and kind because that would mean she was getting heat stroke from the recent hot weather. Later when she starts acting mopey because of Longtail's death, Jayfeather gets really worried about her well-being.
In the Dale Brown novel Sky Masters, normally composed Jon Masters lets the pressure get to him, up to the point of Rant Inducing Slight, something his chief assistant notices immediately.
In the final novel of the Codex Alera, Tavi is rather shocked when his lover Kitai becomes furious with him for carrying on a relationship with her without marrying or courting her. Note that Kitai has never given a damn about Aleran laws or customs (or really ever noticed them, except to snark about them) and her own people's view on this sort of thing is rather more... relaxed. So why is she so bent out of shape? She's actually pregnant with her and Tavi's child, and while perfectly happy to flout Aleran rules herself, Kitai does not want her child to have to deal with the major social stigma Alerans place on illegitimacy.
Vivenna from Warbreaker believes that women should dress modestly with high-necked dresses, with skirts that come down to the calf at least. However, when she decides to become more of an Action Girl, she dons a man's trousers and shirt.
Ham from Mistborn spends the better part of three books mired in interminable ponderings, dilemmas, and hypotheticals. Finally he answers a question with "No", and is believed out of the shock value.
Honor Harrington is generally portrayed as a military professional: killing is an unfortunate consequence of her career, she takes no pleasure in it, and she can be courteous to former military opponents who tried to kill herbecause that was their job. Those who have known her long enough instantly recognize (and are scared shitless by) her change in bearing when she really, truly wants someone to die.
When the very anti-killing Campion informs a mook who helped kidnap one of his friends that if she was hurt, he'd "break his rule" and kill him.
In Artemis Fowl, Julius Root apologizing after referring to another fairy as 'human-blooded' is used to convey just how serious an insult 'human-blooded' is amongst fairies. In the second book, the LEP realise just how screwed they are when the usually gung-ho Captain Kelp orders a retreat.
At one point, Artemis (usually very serious and very articulate) calls Butler and simply shouts "Lollipops!" This makes Butler even more worried than he already is.
Kitty Norville is a chatterbox by nature who prefers to avoid violence and tries to get any fellow lycanthropes she meets to let the human aspects of their psyches call the shots as much as possible. So when she (in human form, mind you) lunges at an unarmed normal man on sight and does nothing but literally snarl when bodily restrained, the first question out of the mouth of someone that has known her for a couple of days is "What did you do to her?"
In A Series of Unfortunate Events Aunt Josephine is extremely obsessed with grammar. When the Baudelaires find her apparent suicide note Klaus begins to analyze the grammatical errors, but Violet disgustedly asks who would care about grammar in their situation. Klaus points out that Aunt Josephine would and realizes the mistakes are actually a coded message.
In the Paladin Of Shadows book A Deeper Blue, Mother Lenka laughing heartily is recalled with horror.
In The Elenium Talen is found to have followed the knights on their mission to Zemoch. When questioned, he stammers and stutters, eventually giving an incredibly unbelievable story about why he followed them. Since Talen has never once been shown to be at a loss for words and has proven the ability to make up believable lies on the spot, this clues the knights in that Aphrael, the Child Goddess, is influencing Talen, since She had wanted him on the mission in the first place and is known to be a horrible liar.
This trope is the clue to Sparhawk that someone is using magic to influence the various kings of Eosia into confining the Pandion knights, as they are believing outlandish claims without any evidence and have turned aggressive towards their allies. It is revealed to be a spell that induces belief being cast by Annias, which is another example because as a church man, he is not permitted to learn magic.
At one point in Galaxy of Fear Lando Calrissian, teaching Zak about playing cards, tells him "A good rule to follow is that if the other guy is acting normal under unusual circumstances, you can bet he's bluffing".
Army of Terror has The StoicPapa Wolf Uncle Hoole, confronted with the Kivan wraiths menacing him and his charges, just... stop fighting completely, take a Pose of Supplication, and wait for death. When someone else drives them away, he who is so good at Dissonant Serenity is profoundly shaken. He is The Atoner and blames himself for their deaths, just as they blame him.
In Spore, well, here's a quote.
Hoole touched the gash delicately. "I will live." The stern Shi'ido tried to look as light hearted as his stony face could manage. "It was not my best landing, but all things considered, I would say it wasn't my worst."
Tash grimaced. Hoole never joked. The fact that he was trying to probably meant he felt worse than he looked.
In LIES, Caine Soren is visibly disturbed by the fact that his girlfriend Diana Ladris A) isn't beautiful anymore and B) Isn't being snarky and sarcastic. He notes that this is a sign that she's finally lost her will to live. Serious business, indeed.
In the same installment of the series, Lana seems to lose hope when she notices Caine isn't being a cocky, arrogant sociopath, actually seeming quite insecure and timid, and remarks; "You gotta give he guy some credit; he has a genius for doing the wrong thing. We actually need him to be the bad guy, and now he's mr. meek and mild."
Devout Catholic Astrid loses her faith in God... And Promptly decides thats a good excuse to throw her brother out a window.
If the mild-mannered Clark Kent started speaking and acting rough and is sexually aggressive, you could bet your lucky stars that he is on red kryptonite. On the other hand, seeing him being overly cheerful and completely without Wangst is not a good sign either (Hypnotic)... Oh, and whenever he is not crazy over Lana, something is definitely wrong.
If Chloe Sullivan wears black, run away as fast as you could. She had donned a black outfit on three occasions - in Rush when a parasite makes her do all sorts of crazy things, in Exodus when she betrays Clark, and in Identity when she renders the bad guy of the week catatonic in a truly terrifying scene. Also, if she does anything to hurt Clark in any possible way, something is very, very wrong.
There's an episode where Michael sends Sam to escort Madeleine to safety. Madeleine isn't hearing of it, offers Sam a beer. Sam refuses the beer, at which point Madeleine starts taking him seriously.
In another episode, one of Sam's old "buddies" comes to him for help. Madeleine can tell something's wrong because Sam stops drinking for the duration of the episode. And in a DVD special feature, Bruce Campbell states that you can tell something is serious when Sam isn't drinking. Though he can be seen drinking during the planning stages of a mission, he almost never does it during an actual operation. So, since it's another (and not infrequently invoked) character trait for him, it might not exactly qualify as out of character.
The Ninth Doctor is cheerful, silly, happy, and above all, calm. Nothing fazes him. Then in a secret lab, he sees a heavily damaged, barely-alive Dalek (in the episode by the same name) — and immediately loses his shit in a big way. In the old show, and in public consciousness even more so, Daleks were often played for laughs. This signals very effectively that on the new Doctor Who, Daleks ain't funny — as everyone else learns quickly enough.
By a similar token, the Tenth Doctor is very decidedly anti-gun, turning one down repeatedly when Wilfred tells him to take one and kill whatever it is that has been predicted to kill him in "The End of Time". The mere mention of the possibility of the Time Lords returning causes him to pick up the gun without a second thought. It's how we know shit just got serious.
He picked up the gun before that in The Doctor's Daughter when Jenny is killed.
Ten is also known to allow terrible things to happen because they represent a "fixed point in time", i.e. something with far reaching consequences that needs to happen lest history be royally screwed. He even destroyed the city of Pompeii himself, and let (nearly) everyone die because it had to happen. But in "The Waters of Mars" he's finally had his fill, declares himself the "Time Lord Victorious", and proceeds to screw up a major historical event. It's rather frightening, and the consequences for him are indeed dire.
"Forest of the Dead": As she's about to make her Heroic Sacrifice, River Song remembers her last meeting with the Doctor — how he turned up on her door with a haircut and a new suit, and left her his sonic screwdriver — meaning that the Doctor had known River was going to die.
When the Doctor allowed Solomon to die in "Dinosaurs on a Spaceship", it was an immediate sign to Amy (and the fans) that something was wrong and cemented the theme that the Doctor shouldn't travel alone.
Yes Minister: Jim Hacker is dead set on a course of action that won't do anyone any favours, and won't be swayed. It's serious enough that Sir Humphrey even drops his incredibly elaborate Sesquipedalian Loquaciousness and tells him "If you're going to do this damn silly thing, don't do it in this damn silly way." This stops Hacker in his tracks.
Mose: Did he just talk? He never talks! Jerry: So THAT'S what he sounds like! Loomer: Dude, you haven't said anything since we've known you. Buzz: Everything's been fine up until now.
In the first season and earlier second season of Dollhouse, anything Topher is against on moral grounds goes well beyond just being wrong. This is lessened with time as Topher develops more of a conscience.
Mayor Wilkins:(to Angel) Yeah, well I'd get set for a world of weeping! I'd get set for a world of pain! Misery loves company, young man, and I'm more than willing to share that with you and your whore!
Similarly, any time that meek, submissive (in early seasons) Willow loses her temper and begins to basically force her bickering team mates to cooperate by chewing them out, typically opening up with a shout of HEYYYYY!
And in the second season premiere, Buffy's attitude problem causes her to get baited easily by the vamps, leaving her friends unprotected so that Willow, Cordelia, Giles, and Miss Calendar get kidnapped by the vampires working for the Anointed One. Xander, normally Buffy's biggest fan, lays it out for her:
In the season 5 finale, Giles is trying, as gently as possible, to explain to Buffy that it may be necessary to kill Dawn to save not only the world but all of reality. Buffy point-blank says she's not discussing the matter until Giles jumps to his feet and shouts, "YES WE BLOODY WELL ARE!"
In an episode, Shawn and Gus find a missing camp counselor's bloodstained pajamas. Later, when Shawn explains how he knew her disappearance had been staged, he mentions how Gus didn't freak out like he usually does when he saw the "blood," meaning he must have been in on the secret.
The first episode involving the Yin-Yang serial killer involves this trope as well. Shawn has to get serious to deal with the dangerous case so he asks Gus to pick up the slack on the wacky jokes and bizarre antics for two reasons: 1) to keep anyone from noticing Shawn himself is taking this deadly serious (OoC for him), and 2) because Shawn needs those hijinks or else he'll crack under the pressure of a case this serious. What's completely in character however, is that Shawn gets Gus to agree to not tell anyone why he's acting like an idiot during a life and death struggle, earning him some confused and angry looks from other characters as it continues.
The framing device of Mystery Science Theater 3000 is that mad scientists Prof. Forrester and Frank are showing the Satellite of Love crew bad movies as part of a twisted experiment. One movie, “Manos”: The Hands of Fate, was SO bad that the villains broke character, apologised to the crew, and tried to cheer them up to get them through the movie. It doesn't really work, as the bots are reduced to blubbering pools of tears and Joel has to take on the persona of Carol Channing to buffer himself against the pain.
Leverage: One of Eliot's catchphrases is "I don't like guns," usually said while reflexively unloading one after taking it off someone else. When he shoots someone (instead of killing him hand-to-hand) in The Big Bang Job it's a fairly good indicator of how seriously he takes this particular mark.
The writers of Mad Men do this on a meta level in Season 4 (which begins a few months after Don Draper's divorce). Don had previously established himself as a moderate drinker who never got more than just a bit lubricated; when Season 4 starts, he's seen stumbling home from bars, being drunk on duty, and being called an alcoholic by at least two other characters. Furthermore, he had previously been a Chivalrous Pervert who would never hit on or be creepy toward any of the women in the office, let alone have an affair or even a one-night stand with one; Season 4 brings on the occasional pass and finally an ill-advised affair with his secretary Allison. Things only start getting better for him when he finds a relationship (first with statistician Faye, and then with his secretary Megannote A relationship that had started platonically when he needed a babysitter to supervise his kids when he took them to California.). However, by this point, everyone — and particularly the audience—has gotten the message: Don's marriage was really important to him despite his seemingly cavalier attitude, and despite his womanizing, he needs a girlfriend/wife to keep him on level.
In the episode "Prototype", the team stumbles upon Khalek, a seemingly-innocent, newborn clone of Anubis, and Technical Pacifist scientist Daniel Jackson flat-out says that they should kill him. Not imprison him, not study him, not try to reason with him. Kill him. Kill him before his Goa'uld genetic memory kicks in and he remembers who he is. His reaction is understandable given the circumstances: Khalek is physiologically closer to an Ancient than an ordinary Human, with all the superpowers that entails, and furthermore he will soon be able to Ascend — and it took nothing short of a Divine Intervention to stop Anubis the first time. Daniel even lampshades this in dialogue: if he, of all people, says this is the only option, then it must be. And yes, Daniel is the one who ends up shooting him, while Khalek is busy deflecting Mitchell's shots.
In the episode "Shades of Gray", O'Neill and Hammond's unusual actions at the beginning of the episode are really the only way to tell that there's more going on than meets the eye.
In the How I Met Your Mother episode "Do I Know You?", Barney, who has recently fallen in love with Robin, takes her out to dinner on Lily's advice to make a good impression so that Robin will take him seriously and not dismiss him as the sleazy, womanizing idiot he usually is. His attempt at being chivalrous and tasteful is so impressive (he doesn't even bat an eye when the buxom waitress practically dangles her breasts under his nose) it completely weirds Robin out and she tries to make Barney act like himself again:
Robin: Hey, so I went to the chiropractor yesterday... That guy bent me over the table and pounded me for a good hour... Barney: Insurance gonna cover that? Sometimes they don't. Robin: That's it? Barney:(polite smile) Robin: Okay... Well, um, today, I was at the dentist, that guy drilled me. All day long. Barney:(polite nod) Robin: He drilled me hard. Barney:(polite nod) Robin: He filled all of my cavities... Come on, man! Barney: Well your teeth look fantastic. Robin: Who ARE you?!
Also, Barney burning the Playbook in season eight was treated by the rest of the gang as a sign that he was serious about being in a relationship with Patrice. It's later revealed he burned the book as part of his "The Robin" play, but it's no less shocking because he genuinely meant it since "[he doesn't] need it anymore".
Adrian Monk has severe OCD and a host of other phobias, such that he frequently needs sanitary wipes. During a garbage strike in San Fancisco, he was so disturbed by the trash bags piled around that he was unable to function as a detective. By the climax of the story, he's driving a garbage truck around, picking up the garbage himself, and fingering Alice Cooper for the crime in a summation that's more implausible than usual. His friends get him to a clean room, and he gets back to normal. Relatively speaking.
There's one episode where a radio host is a suspect in a crime, and Monk appears on his show to interview him. The story of Trudy's death comes up, and one of the hosts offers his condolences. The suspect, who's a serious Jerkass, starts making tasteless jokes. You know Monk is pissed when the normally mild-mannered detective who abstains from physical contact jumps across the table to tackle the man.
And Natalie is not immune either in "Mr. Monk Gets Lotto Fever." Normally, she's very accepting of Monk's OCD behaviors and has a bubbly personality, but when she becomes a lottery hostess, Monk observes her becoming a full-tilt diva. For example, in one scene, she gets incredibly pissed when she trips over some sound wires, getting into a heated argument with the sound engineer, which culminates in the station manager being involved, and said engineer being fired because he's got a hot streak. Monk even says he's observed it when he talks to Dr. Bell:
Dr. Neven Bell: But I see your point about the monkey.
Adrian Monk: All I'm trying to say is... it's not the same Natalie! If you knew her you wouldn't know her! Last night after the show, she got somebody fired!
Dr. Neven Bell: Really?
Adrian Monk: One of the crew, sound guy! There were some wires on the floor, and she was just like [leans back in his chairs and snarls like a raptor] you know, complaining.
Subverted in "The Concert", during The Middle's third season. After an early exit from a spelling bee, an event he had gone all the way to the regionals in the previous season, Brick, usually cool and unflappably optimistic, is angry and then depressed, remaining in his room the next day and vowing never to return to school. His parents are actually happy because it's an emotionally appropriate response from a child not known for them.
In one of the DVD Commentaries for Firefly, Joss Whedon points out that Alan Tudyk has a great ability to sell the gravity of situations just by looking upset.
In an episode of Red Dwarf: When Rimmer seems against filming women in the showers, Holly remarks "Alright, who are you, and what have you done with our Rimmer?"
In The A-Team, when "Howlin' Mad" Murdock drops his psychosis of the week and takes a turn for the serious, you know something big is going down.
Penny pinching patriarch Jim Royle of The Royle Family never misses an opportunity to complain at his mother-in-law or save money. So what does he say to his wife Barbara at her Nana's funeral? "I'd give all the money in the world to have one last drink with her."
And when he wins £100 on a scratch card he hides the fact from Barbara and seems to spend a little too much money out drinking it looks to us and Barbara that Jim is being a selfish miser again. But come Christmas Day, just after Barbara shouts at him for hiding the money in front of the whole family, she finds that Jim had bought her a new wedding ring to replace the one she lost a few months back.
This is Jim in a nutshell. He's usually lazy, abrasive, selfish, tactless and sometimes outright verbally abusive, but when his family really need him to step up, he does the right thing.
Dr Cox of Scrubs is The Nicknamer to the rest of the cast and never lets any of them in emotionally. But once in a blue moon, he'll drop the nicknames and talk from the heart.
Star Trek: Deep Space Nine: "Improbable Cause": after three years and an entire episode full of blatantcheerfulobfuscation, when the crew realises the Romulans are trying to assassinate him, Sisko asks Garak why they'd want to. Garak responds with a simple "I don't know" and the entire room falls silent in shock as they realise he's telling the truth. It emphasises how ominous the situation actually is: as the show's resident Magnificent Bastard and Knowledge Broker, Garak either knows everything or can guess what he doesn't know. To see him so stumped that he's actually cooperating with the truth is as stunning for the audience as it is for the crew.
The Star Trek: The Next Generation episode Q Who? features Starfleet's first encounter with the Borg, thanks to Q's machinations. When he is blamed for the deaths of 18 crew members in a confrontation, he drops all pretenses of being a Trickster GodJerkass and utters a chilling, "Oh please." With those 2 words, the audience (and the crew) realize that Q's amiable persona is simply one aspect of his being, which he can discard at will.
In the Top Gear Bolivia special, there's a scene where Jeremy Clarkson tells his fellow hosts to stick together as they cross the Andes while suffering from altitude sickness (not surprising as they are traveling at 17000 feet, well above the altitude where supplemental oxygen/pressurized cabins are required for aircraft). Considering that this is pretty much the complete inverse of how they usually behave, it drives home exactly how dangerous the situation with the high altitude is.
Also in the above, the trio a traversing a dangerously narrow mountain road with no railings, and James 'Captain Slow' May tells the others not to ram him as they usually would. Normally he would take such taunts on the nose. This time, though, he gets out of his car, goes over to Jeremy's, leans in the window, and proceeds to threaten Jeremy with a machete.
In Dinosaurs, Baby always hits Earl over the head and calls him "Not-The-Mama" instead of "Daddy". When he becomes seriously ill, he starts calling Earl "Daddy" and tells him he loves him. The family freaks out and get him cured as quickly as possible. Everyone is relieved when Baby hits Earl and calls him "Not-The-Mama" after he is cured.
In the final season of 24, Jack Bauer snaps after Renee Walker is killed and goes on a Roaring Rampage of Revenge in an attempt to kill all responsible after the President betrays him by covering it up. Realizing that he isn't in his right mind at the moment, Chloe refuses to go along with him and says that he needs to be brought in, causing Jack to actually threaten her. Chloe lampshades it herself later on that he's never done that before.
Many uncharacteristic moments of affection by Sherlock towards others (especially towards John, Mrs Hudson or Molly Hooper) are listed in the Crowning Moment of Heartwarming page but one notable example is when Sherlock meets Irene Idler. When she says "Brainy's the new sexy" his normally perfect enunciation fails for a second and he mumbles his next sentence. John's expression shows how big a deal this is. Benedict Cumberbatch indicates that Sherlock's verbal keyboard mash happened in response to John's obvious interest in Irene Adler's flirting.
Sherlock offering to do the groceries or making coffee should have tipped John off that something was wrong.
In The Hounds of Baskerville, it's a huge deal to see Sherlock and, to a slightly lesser extent, John, experiencing and expressing devastating levels of fear:
Sherlock: (clutching a glass of whiskey and shaking badly) Look at me, John. I'm afraid.
With one line Sherlock lets the audience know how bad things are in The Reichenbach Fall.
Sherlock: You were right. I'm not okay.
For the entirety of Blackadder's first season, the only line not screamed, bellowed or roared by Richard IV is the one where he softly says to his son, "Edmund... If you ever cross me, I'll kill you." In the whole dark, bitingly cynical world of the series, it's possibly the one time when one of the buffoonishly over the top characters ever qualifies as being genuinely scary.
Myths & Religion
In the New Testament Jesus has a very serious OoC moment known as "the cleansing of the temple". While some people may argue that Jesus could never have acted out of character, there is no doubt that even (and especially) his friends and followers were shocked by what they saw. He was literally the poster boy for patience and forgiveness. But everybody has at least one thing that really burns them up and makes them want to break something/someone; for Jesus, it seems, it was taking advantage of poor and ignorant people in the name of God (the corruption in the Jewish church was along the same lines as the selling of indulgences in Martin Luther's time). When he saw what was going on, he just stood there, looking around and emanating so much anger that he didn't even have to raise his voice for everybody in the temple to know that some serious shit was about to go down if they didn't get out of there. He flipped over a money-changer's table, and the priests and merchants ran like hell.
Jesus: It is written: "My house shall be a place of prayer." But you are turning it into a den of thieves.
Another example would be when Jesus curses the fig tree, causing it to wither and die. This is the only time that he is shown to use his gifts/talents/powers in a way that does not cause life and healing for the recipiant.
There is even a saying about Buddha, the poster boy for patience, serenity, that goes like this : "Even the Buddha will get angry if slapped thrice in the face" for The Stoic finally snapping. Basically, the threshold is high, but if you are stupid enough to repeatedly annoy them, even a Saint is going to snap at you, and it's going to be Serious Business.
Since wrestling announcers are supposed to be loud and talking all the time, it was always a pretty safe bet that when they went completely silent, it was a sign that someone was legitimately hurt (instead of when they kept talking, which showed it was part of the show). However, that's not quite as accurate now, since the people behind the scenes have caught on to this, and have started to use dead air when trying to sell a Kayfabe injury.
While announcers do use the "Owen Voice" as it is known by internet fans, they will make it very clear when a real injury or accident happens, by repeatedly dropping all pretenses of kayfabe and telling the audience that it is not part of the show. This was most recently seen during Jerry Lawler's heart attack during the show. He got drowsy, passed out, started snoring, then there was a silence for a while. While he was being attended to by EMTs, the crowd reacted to it, and Michael Cole tried to carry on commentary for a for minutes while the match went on. Then he went completely silent for the rest of the match. When they came back from commerical, he (in tears) related to the home audience that Jerry Lawler had a heart attack while at the desk and that it was not part of the show. All updates through out the rest of the show were prefaces with "this is not part of the show". Being pro wrestling, it eventually became part of the show when he returned after 10 weeks and top heels CM Punk and Paul Heyman made fun of it by having Paul fake a heart attack in the ring. This was followed up by every heel on commentary making some kind of joke about his heart attack.
Kermit: You never miss the chance to shoot yourself out a cannon, is something the wrong?
A number of character-driven RPGs give characters compulsions to act in certain ways and require expending resources to ignore them, effectively making Out-of-Character a form of Heroic BSOD. For example, Exalted, calls it "Limit Break"*
No relation to the trope
and forces the Solars to either take their greatest Virtue to extreme or invert it, Lunars to act animalistic and Sidereals to stubbornly force Fate into path dependant on their caste.
There are several scenes where Squall, normally keeping himself completely under tight emotional control, will suddenly flip out with little warning when something happens that deeply upsets him. Early on it is after he's told Seifer was killed and he starts wondering what others would think about him if he died. Later on, he flips out when NORG tells him that Garden and the SeeDs were nothing but expendable troops, and he finally starts jumping violently at anything that threatens Rinoa after he admits his feelings for her.
It's generally a bad sign whenever a member or former member of the Omega Team in Last Scenario changes expressions. Helios really takes the cake, though—no matter what you do to him, he never stops smirking, right up until the sequence in which he sacrifices his life to let Castor escape.
In the Shivering Isles add-on for The Elder Scrolls IV Oblivion, your biggest clue that things are about to go bad is when Sheogorath tells you you're out of time with an explaination of the concept of time, which is a bit too orderly and lucid for the usually chaotic and wacky Sheogorath, indicating that he's about to become Jyggalag and begin the destruction of the titular isles.
The Motor Mouth salarian doctor Mordin Solus never uses personal pronouns. Except once, in the third game, if, when trying to talk him out of curing the genophage, you point out he was the one who previously helped strengthen it.
Mordin: I MADE A MISTAKE!
This is a double OoC moment, as Mordin normally never shouts. Makes the moment all the more poignant. On a lesser scale, he says "My mistake" on his loyalty mission when he finds out that Maelon was not kidnapped and instead was voluntarily helping to cure the genophage. The key word in both of these examples is "mistake." Mordin is never insensitive to the consequences of his actions, but his tremendous intelligence and pride make it difficult for him to acknowledge when he's made a bad decision, which means he'll defend the genophage modification as distasteful but necessary every time you confront him about it up until you reach the Shroud.
He does also use a personal pronoun on at least two other occasions, one time being a callback to the previous time
Mordin: Had to be me, someone else might have gotten it wrong.
Shepard him/herself has one after the fall of Thessia. Normally, when Shepard responds to someone saying something inappropriate, s/he will have at least one option to say something that's at worst, mildly chiding, or ignoring it. After Joker makes a very unfunny crack, Shepard's "Paragon" responses is snapping at him. An earlier Shepard moment occurred in the Project Overlord DLC. You know Shepard's pissed off when the usually noble Paragon interrupt is to pistol-whip someone.
There's a popular saying that goes, "You will only see a turian's back when he's dead," which makes their retreat from Palaven near the end of the game show just how serious and hopeless the situation against the Reapers is.
The usually calm, if eager for a fight, Wrex will snap completely if you sabotage the genophage cure in the third game. It's actually scary seeing him shouting at the top of his lungs and firing a shotgun at Shepard - but then again, his unborn son just died.
In Tales Of The Abyss, Jade says, after weighing the possible benefits of Luke sacrificing himself, tells Luke that "as (his) friend" he feels compelled to stop him, prompting Luke to point out that he never called him his friend before. Jade then apologizes, something that's equally uncharacteristic of him. Much earlier in the game, Jade gets visibly angry when he realizes that the villains are using fomicry.
Kyrie Florian is a flirty, coy, and playful character with a manipulative streak who doesn't seem to take things too seriously... unless if something she really cares about is brought up, such as her dying planet or her dying father-creator, then that personality drops, showing The UnfetteredDeterminator underneath.
Levi the Slasher acts like a hyperactive Cheerful Child practically all the time, save for near the climax of the game when she decides to join Stern in her Suicide Mission to stop the growth of the Unbreakable Darkness. Here, she expresses a rare moment of seriousness and thoughtfulness that surprises Stern and ultimately convinces her to allow her fellow Material to help her with her plan.
Given the tragic ending of Super Metroid, this appears to have been the intended trope for Samus Aran throughout much of Metroid: Other M. However, no previous personality had been properly established for her outside of an obscure manga, so most people interpreted it as the norm for her, and were not pleased. She does display some Not So Stoic moments in the game though.
In World of Warcraft, Thrall's teacher Drek'thar has been gradually becoming senile, so whenever he becomes lucid, it's a sign that he feels strongly about something. He does so in The Shattering Prelude To Cataclysm when he hears about Cairne Bloodhoof dying, demanding to know how he could have been killed. He dose so again in a quest in which the player asks him to help the Forsaken war effort; since he is a repentant Old Horde war criminal who is haunted by the memories of the atrocities he committed, he is horrified that the Forsaken could commit similar atrocities without feeling anything.
In Ace Attorney, Phoenix is always flustered or worried about his cases in some way. But sometimes, he stands perfectly still and and speaks calmly and with absolute confidence. When this happens, not only will he find the killer, but they'll probably be convicted of half a dozen other crimes too. The first time is in game one case four. After Phoenix clears his client of one murder, they admit to another. Naturally, he doesn't believe they did it. In the ensuing recess, Maya freaks out and then asks Phoenix why he's looking at a photograph. Phoenix's response? "I'm preparing our case."
At one point in 2-4 he actually manages to intimidate the judge, something usually reserved for the prosecution or certain witnesses.
In Case 1-3, Edgeworth starts to morph from being a jerkass to a Jerk with a Heart of Gold when he helps prevent Dee Vasquez from escaping the court by demanding she testify about after finding the body (which Phoenix hadn't thought to ask her). The only reason Phoenix can think of for why he did this was because he agreed that the evidence was compelling enough that Vasquez was the real murderer, but this was the first time that he put finding the true criminal above maintaining his perfect trial record, which had been shattered in the previous case.
In Apollo Justice: Ace Attorney, Klavier is typically laid-back in court, even when Apollo pokes holes in his arguments, and enjoys using Gratuitous German. When Vera Misham's testimony indicates that she was responsible for forging the page out of Magnifi's diary, which Klavier uncovered on a tip from his brother and got Phoenix disbarred, Klavier is visibly shocked, and calls her "Ms. Misham" rather than "Fraulein" or other variants thereof.
Later, when Kristoph is on the stand, Klavier becomes much more hardcore in his prosecuting, blocking most of Apollo's arguments. Trucy speculates that he wants to impress his big brother.
In general, most of the witnesses will have a breakdown point where, if they're pretending to be sweet, naive, innocent, or any other personality type, they'll drop the act altogether. In the case of characters like April May or Dahlia Hawthorne, it can be pretty scary. In the case of Yanni Yogi, who completely drops the braindead routine he'd been using for the entire case, Maya even comments that he seems to be a different person entirely.
After she and Edgeworth almost get shot by Callisto Yew, Franziska's confident front fades and she is visibly frightened.
Similarly, the single time when Kenji calms down enough to speak reasonably and offer Hisao emotional support, you know it's gonna bring up a Tear Jerker.
In Emi's route, when Emi and Hisao meet after throws Hisao out of her house, Rin becomes surprisingly direct and to-the-point.
Rin: Hisao is kind of worried about you, Emi. I don't think he can decide, or maybe I don't believe him, but I think I'm going to go somewhere less awkward now. Hisao Narrates: I'm so surprised by Rin's being so suddenly forward about well, anything at all, that I merely watch her head through the door.
Hanako exploding at Hisao in her bad ending. She also tells him to "...Go away" when he tries to check on her in Lilly's route, surprising him.
In Lilly's route, Shizune, a typically blunt girl who has a rivalry with Lilly, responds to Hisao telling her that he's going out with Lilly by saying that it's his business who he dates, and she hopes they go well together, which Hisao implies is her not saying what's on her mind. She then is about to say something more, but has Misha not translate her signing, which makes Hisao wonder why Shizune would pull a punch or speak without forethought.
In Fate/stay night, in the Heaven's Feel route, it is the first cue for the player who went through Unlimited Blade Works and witnessed firsthand the insane determination Archer puts into accomplishing his goal, killing his younger unwitting self Shirou, that some VERY SERIOUS shit is about to hit the fan when Archer witnesses the damage done, and at the drop of a hat, postpones his personal vendetta with Shirou, to switch back into full Counter Guardian mode, and deal with the more pressing, in the end literally world-threatening, issue of the Shadow.
The trolls all have a characteristic quirk or two when it comes to communicating through their messaging system. When Gamzee's changed from "hOnK" to "honk HONK", signifying that he's now sober and completely Ax Crazy, Karkat freaked out. (Along with the rest of the readers.)
CG: OH MY GOD CG: NO NO NO NO NO NO NO
Feferi and Eridan typically have very distinctive typing styles, but drop their quirks briefly to have a serious conversation about Feferi being Eridan's Morality Chain.
As of Act 6, you know something's up when Terezi, who is normally the resident Handicapped Badass and The Chessmaster who is obsessed with smelling and tasting everything as replacement for her missing eyesight, suddenly starts hiding her eyes behind her dragon hood and acts more withdrawn. It would seem that meeting the pre-scratch version of her ancestor made her feel more self-conscious, and some of her behavior could also be caused what is revealed sometime later that she and Gamzee are filling a black quadrant together.
Later in Act 6, when Gamzee is staring with a blank expression at something, you know it's weird.
When Torg starts to actually think (or simply stops acting silly), you know business has just got serious. Often coupled with Let's Get Dangerous.
In "Oceans Unmoving", Honest Stu always tells the truth, the whole truth and nothing but the truth — no matter how awkward or dangerous the occasion or rhetorical the question. The one time he actually lies, and just for the fun of it too, is when he is dying, very nearly with his last words.
Belkar again after Malack kills Durkon and turns him into a vampire spawn. Roy is so furious and disbelieving at Belkar's account of the events he threatens to kill him. But after he tells them about Durkon asking Malack to spare the rest of the Order, Haley believes him because she doesn't believe the canonically Chaotic Evil Belkar is capable of making something like that up.
In Questionable Content, the normally-calm-and-passive Marten is furious after Dora flips out on him and Faye for thinking they were fooling aroundnote actually Marten calming Faye down from a panic attack, which startles Faye.
Vixen of the Desu Des Brigade is very relaxed, informal and happy in most of her reviews, even in a lot of the shows that squick her out. Then came her Film Fox review of The Twilight Saga: New Moon, where she's in complete distress with no escape throughout and screams more than once.
She never apologizes. So when she tells Nella that she's sorry for not including her in a review, you can see the manipulation coming a mile off.
More seriously, The Christmas Shoes was so awful about having the kid (whose mother was dying) being taught the values of earning money that she — a self-admitted Child Hater — ended up screaming at the adults for how monstrous they were acting.
The Cinema Snob (real name: Brad Jones) has done this on several occasions.
He starts his review of Caligula out of character claiming that it's his favorite movie and that it's going to be hard to "Snob" it.
During the film Elves, the main character's stepmother kills her cat. Brad (a well-known Kindhearted Cat Lover) snarls, "I'd kill her. I'd fucking kill her!" — without any of the Snob's usual tone.
At the end of his review of Goldengirl, Brad Jones went so far as to take off his glasses and unslick his hair before telling his viewers to seek out the film, just to make it clear he was serious.
The review of Gross Out starts with Brad almost begging his viewers not to watch the review. To put it in perspective, he didn't do this before the review of Pink Flamingos.
Burt from We're Alive usually can't resist an opportunity to quote from his favorite movies. But in chapter 23, he and Angel are trapped in a hospital room with zombies at the door and their only escape, a Bedsheet Ladder, broken. Burt yells for the other two characters, who got out, to leave them and run for the helicopter on the roof of the hospital by saying "Get to the chopper!" Angel asks if that was a quote from Predator. When Burt "What?...Oh, no, it was just a coincidence." Angel goes into Oh Crap mode.
In Episode 12 the Lazy Bum Grif, who usually tries to find time to nod off, can't.
Grif: I never thought I'd say this, but I can't sleep.
In Episode 13, the pervert Tucker, who always finds a Double Entendre for anything said, doesn't say it.
Tucker: Church, just because you want to get close to someone doesn't mean that you have to end up inside them! *Beat* Church: ...Oh come on. Aren't you gonna say it? 'Tucker: No, because I'm pissed off!
After Church rages at the crew in Episode 18, Caboose leaves Epsilon-Church despite his prior Undying Loyalty, driving home just how crushed the Blood Gulch Crew is at that point. That said, he does get over it quickly enough, so it's probably more that he was upset that Epsilon-Church was alienating his friends than anything else.
In the same episode, who is the first to leave? Lazy Grif, who typically just goes along with whatever crazy scheme everyone else comes up with because it's too much work to disagree with them.
In Danny Phantom, the only time Sam acts really cheerful is around Christmas, even though she's Jewish. One of the kids at her school was so freaked he thought it was A SIGN OF THE APOCALYPSE!
Happens a few times in Teen Titans, such as when Perpetual FrownerRaven acts cheerful for whatever reason, like in "The End Part I" (when this was just an act) and "The End Part III" (when it was genuine). Also when the Hot BloodedRobin doesn’t yell at his team to insist he’s fine after he breaks his arm and instead decides to give up and watch television in the episode “Fractured”, much to the shock of his friends.
"Lake Laogai": Longshotspeaks just once as Jet is dying... and it stuns everyone who hears him because it's so rare. It stunned the fandom just as much; up until that point, nearly everyone thought he was a mute!
The eponymous Avatar is usually a very happy-go-lucky kid. He's very peaceful and spiritual, and has stated repeatedly that he doesn't eat meat. Then in "The Desert", his best friend and pet since he was a kid, Appa, is stolen by Sandbenders. The normally cheerful Aang spends the entire episode being cranky, aggressive, and angry. He even kills a wasp-buzzard that tried to take one of his other friends even after the threat it posed was gone. When they run into the Sandbenders who stole Appa, you know they're infor a worldof hurt.
The sequel series The Legend of Korra has Tenzin very surprised by Korra's refusal to join the anti-Amon task force. While he was glad she didn't, he recognised that her unwillingness to charge her enemy head-on was very uncharacteristic, and (correctly) guessed that Korra was truly afraid for the first time in her life.
In the last story arc of the first season of Transformers Prime, Megatron almost kills Rafael when he attacks Bumblebee with a blast of Dark Energon. Optimus Prime declares, in no uncertain terms, that he intends to KILL Megatron for what he's done. Few characters in fiction adhere as strictly as Optimus does to Technical Pacifism, and seeing him actually show a vengeful streak shocked even his fellow Autobots. He actually sticks to this policy later — while he and Megatron are forced to ally against Unicron, Optimus shows he is still going to terminate Megatron if he gets the chance now — fortunately Dreadwing intervened.
Another example, and once again with Optimus: when Starscream uses his Red Energon speed serum to steal all the Omega Keys at once Optimus actually loses his cool and shouts in impotent frustration. Ratchet and Bulkhead are actually visually distressed at watching Optimus break like that.
In Scooby Doo And The Alien Invaders , Scooby and Shaggy each fall in love. When asked what they want to eat, the normally bottomless pits say they aren't hungry. Cue Ironic Echo and the rest of the gang looking at each other in shock.
On Scooby-Doo! Mystery Incorporated, Velma goes through this as the series concludes. She usually counts on rationale, logic and facts to guide her and the gang through their mysteries, but when the Curse of Crystal Cove sends them through a nightmare realm where those that have been associated with the search for the cursed treasure remain, Velma feels that logic and reason have failed her. As a result, she breaks down crying.
Wade Duck of the US Acres portion of Garfield and Friends, while not literally afraid of everything, is afraid of so many things that most people wouldn't even consider (e.g., he is canonically afraid of caraway seeds) that the other farm inhabitants seem to think it the case. So when Wade, having his cowardice suppressed via hypnosis, passes by performing a stunt on a bicycle...
Booker: It looked like Wade, but it didn't tremble like Wade...
In the Ed Edd N Eddy episode "Little Ed Blue", Ed, who is normally the resident Perpetual Smiler, spends the episode angry, bitter, and has a huge need for isolation from everyone else, including his own friends Edd and Eddy. Edd is concerned, and Eddy is too impatient to deal with it, and because of Eddy's impatience, Ed goes on a rampage, until Jonny and Plank show up and everyone finds out that Ed has a pebble in his shoe. It's very telling that Sarah, who will willingly jump on and beat the crap out of anybody up to and including Rolf (physically the strongest among the kids except for Ed), looked at Ed much as the Eds look at her when she's mad and told everyone to back off the instant she realized Ed wasn't backing down.
The new South Park episode "Going Native" has Butters become hostile towards the other characters.
Cutie Mark Failure Insanity Syndrome shows up for each character in the mane cast, with that character's personality changing dramatically in response to outside stress, especially stress related to that character's talent. Seeing the showoff Rainbow Dash suffering from stage fright in "Sonic Rainboom" or the usually steadfast and honest Applejack lying to her friends in "The Last Roundup" is mindboggling. The issue goes to outright terrifying with Pinkie Pie's laspe into depression in "Party of One", Fluttershy's lapse into Yandere at the climax of "Best Night Ever", and Twilight Sparkle's complete psychotic break in "Lesson Zero".
In "Lesson Zero", Princess Celestia flies over to Ponyville right after she fulfills her sun-related duties, fixes Twilight's mess, and sternly reprimands her. This is the first time in the series that Princess Celestia has shown any disappointment in Twilight, let alone the outright anger she expresses upon first realizing what has happened.
Earlier, near the end of Part 1, her disappointment in Twilight is such that it again moves straight into actual anger. The result is even more chilling than it was in "Lesson Zero."
Fluttershy does this all the time. She is normally extremely fearful, but when her friends are in trouble, she'll stand up to a manticore, a cockatrice, or a giant firebreathing dragon. And if there isn't a threat around, it means trouble for her friends (see "Putting Your Hoof Down" and "Dragon Quest" for examples).
Big Macintosh, who is normally calm, collected, and quiet, chewed out the Cutie Mark Crusaders for printing embarrassing details about him and Applejack in "Ponyville Confidential". You know you really screwed up when you got him mad enough to say more than a few words.
In "Keep Calm and Flutter On" when Celestia brings Discord to Ponyville in an attempt to reform him, the mane six are furious that she would bring the worst villain they've ever faced anywhere near them, even Twilight - who is usually intensely reverent of Celestia and terrified of disappointing her - outright yelling at her.
In episode "The Uncertainty Principle", Jameson spends the first half of the episode being very quiet and subdued as his son, an astronaut, encounters problems that could get him and his crew killed. Once he's safely back on the ground, though, Jameson only takes a moment of serene thankfulness before instantly reverting to his usual No Indoor Voice/Motor Mouth bossiness as he orders everybody to throw together an issue praising his son's success.
He also does this when he heard the victim of the heart attack was Peter's aunt, going from wanting it on the first page, to wanting to tell Peter himself.
The Simpsons: When pre-Flanderization Ned Flanders snaps in "Hurricane Ned", it very much has this effect, since the usually mind-mannered and nice-to-a-fault Ned absolutely rips into everyone in Springfield, and all he says to Homer is that he's the worst person he's ever met. It's not especially surprising when Ned checks himself into a mental hospital immediately after.
If there is ever a moment where Bart is studying or behaving, expect a reaction from everybody.
In the Dragon Tales episode "Hide and Can't Seek", Ord has so much fun playing hide and seek he asks if he could eat later, much to his friends' shock.
In your average episode, Phineas is almost spookily optimistic and cheerful. It makes sense that a few of the specials ("Summer Belongs to You" and "Christmas Vacation") and the movie have moments in which he's sad or angry just to let the audience know that these aren't normal episodes. One line in particular became Memetic Mutation, even though it would have been no big deal if someone else had said it:
Phineas:GET ON THE TRIKE!
"The Lizard Whisperer": Ferb must really love Steve the chameleon, because when Steve goes missing and Phineas and Isabella are on the verge of giving up the search, he delivers a long and epic speech to urge them on.
In the Beach Episode, Linda becomes very concerned when she doesn't receive a call from Candace about the boys' activities.
In Justice League Unlimited, a season finale sees Lex Luthor divide the League, make the public hate and fear them, and he tops it off by merging with Brainiac to be a limitless technological god-being who defeats the primary League members singlehandedly, leaving only the Flash left to kill. The normally happy-go-lucky Flash runs away... and returns having circumnavigated the globe in seconds to build up the speed to hit Luthor/Brainiac hard enough to hurt him. Appearing deadly serious, Flash does this nearly a dozen times becoming a literal bolt of lightning pummeling Luthor into dust. Until this episode, nobody realized that the most powerful member of the team was not Superman.
There's one episode, in all the DCAU, where Batman laughs, and it's one of the darkest
Harley Quinn: I've never heard you laugh before...I don't think I like it...
So anyone who's seen Gargoyles knows that, in battle, Goliath is a force to be reckoned with. Off the battlefield, he's thoughtful, considerate, even downright philosophical at times. He's not afraid to pull out all the stops in the heat of combat, yet repeatedly chastises others for going overboard when it's unnecessary. But push him too far and he will get pissed. In "Hunter's Moon", the second season finale, his daughter Angela is beaten almost to death by the Hunters... at which point the noble, level-headed clan leader growls, his eyes glowing, and in a scene that's drawn like he's looking out from the very gates of Hell - on a DISNEY AFTERNOON show to boot - intones the following:
In the Kim Possible Episode 53, "Emotion Sickness", both Kim and Shego are victim of "Moodulator" chips and are subject to drastic mood swings, scaring Ron and Draken, respectively. It should be noted that both men are way more unsettled when Kim and Shego are acting very amorous toward them as opposed to angry.
Spoofed in Family Guy's "And Then There Were Fewer" two-parter:
Lois:(thinking) Peter, we've been married twenty years, please recognize when I'm acting out of the ordinary because I'm in danger! (out loud, grabs car keys) All right, here you go, Pete! Peter:(thinking) Why's she calling me "Pete"? We've been married fourteen years, she's never called me Pete. Why am I even thinking about this when I could be listening to my tapes?(out loud) Bye! (leaves immediately)
In the Jimmy Neutron episode "I Dream of Jimmy" Jimmy goes into Carl's dream and tries to wake him up. All his attempts to convince him he's in a dream fail... until Jimmy kisses his rival Cindy.
Carl: Jimmy kissing Cindy? Oh, that couldn't happen in a million years! I must be dreaming...
In an episode of Littlest Pet Shop, Mrs. Twombly (normally a very kind and sweet woman) was so enraged at Fisher Biskit for outbidding her on a doorknob that even the mention of his name angered her. After she hears about the open house he's having where he will be showing off his art collection, she slams her fist into the counter, causing Blythe to scream and shout "So out of character!"
In Dastardly and Muttley in Their Flying Machines, The Vulture Squadron's card-carrying coward Zilly becomes brave to gung-ho levels in the episode "Zilly's A Dilly," thanks to hypnotism. However, his devil-may-care bravery becomes more of a hinderance to the squadron than when he was a coward.
A soldier from the Second World War managed to invoke this trope unintentionally; he was well known for having a very poor grasp of punctuation, and once joked with his wife that if he ever sent her a perfectly punctuated letter, she should underline the first word of every sentence and it would reveal a coded message. When he was captured by the Nazis and put into a labour camp, he remembered the joke, and sent his wife a coded message hidden inside a well punctuated one. It worked, and his wife, with the help of the British government, managed to smuggle various items to him which he used to escape the camp.
Speaking more broadly, a sudden change in behavior can be a sign of mental illness.
It may also be a sign of neurological or even vascular issues as well. A sudden unexplained personality change in a close friend or family member should be treated as serious and indicative of a possible medical emergency.
A sudden uptick in someone's mood after a long depression may be a sign that they're happy that their problems will soon be over. Because they're about to kill themselves.
Before Hurricane Katrina hit New Orleans, the local National Weather Service office issued a bulletin. This is standard, but sentences like "PERSONS...PETS...AND LIVESTOCK EXPOSED TO THE WINDS WILL FACE CERTAIN DEATH IF STRUCK" and "WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS" are decidedly not. After the hurricane, authorities credited the bulletin with saving thousands of lives.
Many Republicans accused New Jersey governor Chris Christie of being a traitor when he supported Barack Obama's plan to bring financial aid to the victims of Hurricane Sandy.