In chapter 24 Asuka wakes up and finds Shinji hugging her. Shinji (believing he is dreaming) calls her beautiful, says that he’ll make her breakfast in bed and wash her back when she is in the shower, kisses her, winks at her and leaves. She remained stunned for several minutes:
Asuka kept staring at the door he’d left through for a long time. “What the fuck just happened?” she finally asked the empty room.
In chapter 49 Asuka is very, very, very angry. Shinji decides to try to placate her (even if he has never manages to calm her down when she is exploding)… and he manages to tell the exact right thing for once.
Asuka: "Pretty smooth, Baka-Shinji. Who are you and what having you done with the Third Child?"
In chapter 54 they have to decide the punishment of a bloody dictator, mass murderer and rapist that their army has apprehended. Asuka thinks that Shinji will want to be merciful because he hates to kill… and then he told that he wanted to kill him because he was like the people that hurt Asuka. She got shocked and puzzled:
Shinji: “We… when we were talking about Don Barceló, and what to do with him? And you said he was like the ones who hurt you? When you said that, I… I wanted to burn him.” Asuka: “That is… not very like you, Shinji,
In chapter 4, when Shinji learns his father took Rei in after abandoning him, he is so furious it gets Asuka shocked:
Asuka blinked in surprise. Shinji was… furious. She'd never seen him this angry. The usual calm expression he gave the world, or the warm and loving one he showed her when they were alone was gone. His face was twisted in a violent combination of anger, pain, and betrayal. She'd seen the Third Child without his clothes a lot in the last two weeks, but she'd never seen Shinji this naked.
In chapter 8 Rei is undergoing a memory scan. It is a long, tedious process, but Rei never complains, gets bored or tired. So that when she actually displays resignation and impatience, Ritsuko -who oversees the scan- becomes startled and wonders if the emotion suppressants they fed Rei with are not working.
Ritsuko flicked another momentary glance at the First Child. That reply had been... no, that couldn't have been resignation. Rei didn't get bored.
Rei also experienced Hate at First Sight with Kaworu (even physically assaulting him), which everyone has a hard time believing.
Nope. I must be wrong. Rei did not drag the new transfer student off somewhere and slap him. Not our Rei. That… can’t be it.
After her initial –and very angry and volatile reaction-, after coming to terms with the idea of becoming a mother, Asuka starts displaying a mellower, kinder attitude gradually. It disconcerted Shinji, Misato and even Rei.
Misato and Shinji are completely amazed by their roommate's bizarrely calm (for her) behavior. As usual, the First Child could think of nothing to say.
In chapter 2 Maya is surprised and amused when Ritsuko tells her that Misato is panicking.
In chapter 4 Asuka woke up early, tied her hair behind her back, put an apron on and made breakfast. Shinji and Misato were left speechless.
Shinji (seeing Asuka cooking):"Gulp..." Asuka (frowning at him):"Hey! I CAN cook sometimes!" Misato:"Huh?....." Shinji:"W-what...you..." Asuka:"Oh, stop that! I have the right to dress any way I want and to tie my hair so you won't be hurt by its divine beauty!" Misato:"It's just...so unusual..."
In chapter 4 Asuka tries to be nice to Touji and Kensuke. They can not believe it.
She then smiles warmly and bows to them. Toji and Kensuke are floored yet again. To see such a display of politeness from the most arrogant girl they've ever known, who couldn't let a day pass without calling them some insulting name or other...they're on the verge of fainting.
In chapter 6 Asuka gives Shinji a chocolate box stating it was a Japanese tradition… something she usually does not care about at all. Shinji gets shocked.
Shinji (surprised):"You...? Obeying something? Let alone a tradition? You must be feverish!"
Children of an Elder God: Rei is usually calm, quiet and soft-spoken. It is hard to get her angry. Then in chapter 4 she saw Asuka wrapping her arm around Shinji's. She was so consumed with jealousy she actually growled and clenched her fists while she glared at Asuka. When Touji and Kensuke saw she was actually mad, they freaked out.
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'.
Higher Learning: In chapter 34, during a tense confrontation, Kaoru manages to get cool, stone-faced Gendo shocked and confused. Kaji stepped back when he saw that because he did not know what to expect.
Gendo's eyes widened behind their glass shields. Kaji had never seen such a reaction, and took a step back, not knowing what to expect.
In chapter 10 of Once More with Feeling, Asuka admits that she screwed up in front of Rei, Rei apologizes for Asuka, And Shinji goes slack-jawed for a bit wondering why nobody told him that the Earth had started rotating from West to East overnight.
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.
Hobbes stared at Calvin. Never in his entire life had he saw Calvin break down sobbing.
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?", stating that Kenshin would never insult her cooking (and is also probably thinking that her legendarily bad cooking shouldn't be news to anyone).
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 Shizune's 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.
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 Mikaela.
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 she's not even consciously aware of 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.
For someone who isn't afraid to swear, Valkron appears to be limited to "hell", "arse(hole)", "damn" and "bloody". This is because he only does a Precision F-Strike when he is seriously angry.
Insufferable Genius Samaroh drops his entire pompous smarter-than-thou attitude for a more gentle and softspoken bedside manner when caring for the injured. The biggest Deadpan Snarker of the story is surprised at this.
Combined with Precision F-Strike in The Next Frontier. If Bill Kerman uses a real swearword, the situation is serious. The first time he does it in the fic, the normally unflappable Jeb is appreciably freaked out.
In the Megamind fanfic Rain On The Just, Megamind has been working hard to say "hello" at least closer to correct way. So when he comes to rescue Roxanne from the Beetle-Bomber/Fire Bug/Owen and says "Ollo," she knows that her boyfriend is serious ticked off.
In the ×××HOLiC fic Transitions, when one of the main characters switches universes without realizing it at first, Doumeki wonders if he should get a doctor for Watanuki, because after spending several minutes in his presence he wasn't insulting or yelling at him. He really begins to freak out when Watanuki starts holding his hand. Meanwhile in the neighboring universe, Watanuki gets weirded out when Doumeki is smiling and acting affectionate. In both chapters, the alternate universe versions start panicking when they realize the other is suddenly on a Last Name Basis.
In the MLP Fanfic What Have You Done, Twilight Velvet, Twilight's mother goes to talk to Twilight, who was kicked out of her brother's wedding. She gets very worried when she can't find Twilight in any of the libraries or bookstores in town, which is where Twilight goes when she is upset. When Velvet learns about her fight with the Mane 6, and the fact that they don't know where she is, she starts panicking.
Joker becomes extremely worried when EDI starts drinking, using contractions, and violating regulations frequently. This turns out to be caused by EDEN's hacking of EDI having scrambled their programming together.
In the sequel, Misato surrenders much easier than most of the Wunder crew expected. That's because she's been replaced by EDEN.
Jinx in The Measure of a Titan can't even imagine how bad things must be for Starfire to rip through about a foot of solid metal and explicitly threaten the Hive Five with death. Answer: Robin got shot in the chest.
In xLilyStarkx's Avengers fanfiction "Chained", Tony manages to make Loki cry. Everyone who sees Loki in this state reacts with this trope.
Yukari leaves without telling (20XXIII) and, when she does, it is made note of how worrying that is because it's unlike her to do so, as she would usually be sticking around to suffer with them and/or for them and that if she did leave, she will have told someone and, if she had wandered off, being so mentally unstable, they would have found her. Naturally, their prompt assumption is that she left to die so she would be one less mouth to feed when food is so scarce. In 20XXIV, it is given more weight when she says something coherently instead of rambling.
In chapter 93, 20XXV, Marisa did note that Reimu typically didn't talk much and not once swore (specifically, she said "ass" to them) at Ran and Ren and neither did she go against them and hold her ground, instead of submitting, be that reluctantly, as seen in earlier chapters. Eight chapters later, she says something shocking, during which she challenges Baka to kill her.
In Foundling (a branch off), chapter 13, when Reimu becomes sick, Yukari opts to leave the house without her veil, an escort, doing her hair, putting on some makeup, decent clothes or even shoes, which meant the situations was serious, doubly so since Yukari is mentioned to hardly even leave the house.
Steve realizes that he's done something bizarre or wrong after breaking some robots in The Joke when even Agent Coulson is gaping at him.
In The Many Doors of Níu Heimar Steve draws a caricature that Loki finds so funny he bursts out laughing. Everyone else, particularly Thor, stares at him in concern.
In Marching Orders, Xander makes a nurse and doctor understand just how serious the situation is when he explains that as Sunnydale residents, they have an idea of what goes on at night. He and his friends dealt with it everyday for years and they're leaving Sunnydale immediately.
Played for laughs in Monsters In Paradise. Marisa, the setting's local Kleptomaniac Hero who never returns the things she "borrows", admits to returning a book and entering the Mansion through the front door. In response, Patchouli and Sakuya both decide who will inherit their belongings in the event of their deaths, while Koakuma tearfully denounces her prank-loving lifestyle. Since the situation wasn't all that serious, their comments annoy Marisa and nothing more.
The Fifth Act: Angeal cherishes his honour and takes pride that he will do the right thing. That goes out the window when he slowly starts to die of degeneration. Then he deliberately tricks Cloud and sells him out to Hollander in search for a cure.
In A Different Path, Soi Fon (normally Lawful Neutral at best and a Knight Templar at worst) starts contemplating disobeying orders, and indirectly helps Ichigo's friends by informing Yoruichi, when Yamamoto declares Ichigo's arrancar allies are to be killed and Ichigo brought in for questioning. If Ichigo resists, he's to be killed as well. Even Soi Fon admits Soul Society owes Ichigo too much to go through with such madness.
In the Buffy the Vampire Slayer/Stargate-verse story Trick Or Treat, O'Neil realizes something very very bad happened when Xander calmly asks, "Who is Kinsey?" when, upon being asked if he knew the man a day prior, Xander showed no recognition at all. The reason: Kinsey ordered a raid on Xander's place and got one of his Slayers killed.
In Rewriting Mistakes, Glynda realizes that something's wrong with Ozpin when he starts drinking coffee, which he hates. The reader knows that Ozpin just foresaw a Bad Future.
Enforced in Butterflied when Xander tells his padawan Obi-wan that they're on Obi-wan's quest and Xander will only step in to save his life, thus making every decision Obi-wan's. So when Xander prevents Obi-wan from entering a cave, the young padawan is notably alarmed.
True to the Bat-series, Stephanie Brown/Spoiler is one of the most upbeat, goodhearted characters in Angel of the Bat... With two notable exceptions. During her rematch (from her time as Robin) with Scarab, when the villainess openly taunts her for her failures as Robin and Black Mask sexually assaulting her, she flies into an Extreme Melee Revenge and it takes Batgirl's pleading for her to not kill Scarab with her bare hands. Later, when Cassie is capture by the resident Church Of Evil, she confronts Jason Todd/Red Hood, the only person who knows her location. Steph is almost unnervingly quiet throughout their fight, and, recalling the experience to Cassie, is pretty sure Jason pissed himself towards the end.
In The Nighthawk Chronicles, Xander realizes the Slade he's fighting isn't the real one because his fighting style is too flashy and relies too much on raw power.
In Code Geass: The Prepared Rebellion Euphemia, normally the friendliest and least confrontational character in the story, rips Cornelia a new one for both her attempts at recreating the Shinjuku Massacre and for hiding it from her. Euphy coldly tells her that Cornelia's refusal to perform her own duties as Viceroy and not informing the Sub-Viceroy (Euphy) of military operations within her jurisdiction are both serious crimes, even for an Imperial Princess. Likewise, Euphemia is sick of Cornelia monitoring her finances, reading her mail, and having her Knights follow Euphemia everywhere.
Whenever Keitaro becomes serious in Ancestor, he's talking about something very important/serious, even more so when he raises his voice. Such topics include having to disown Kanako if she stops training before she's mastered their style and massacring an entire village for what they didto his daughter.
In Naruto: The Gamer Files the normally laid-back Kakashi becomes dead serious when he warns Sasuke that if he uses the Chidori against Naruto or any other Konoha shinobi, Kakashi will kill him.
In Eroninja, Tier Harribel the Gobi deeply values her subordinates and is generally a fairly peaceful person, so it shows how deeply she cares for Naruto that when Apacci threatens him (thinking he'd somehow subverted Harribel into sleeping with him), Harribel warns all three that if they do anything to harm Naruto, her retribution will be swift and terrible.
Lucina Reacts: Maribelle spots Tharja crying. This is revealed to be due to Tharja being heartbroken to having permanently lost Robin to someone else.
In one chapter of the Weasley Girl trilogy, Neville Longbottom stuns the entire house of Gryffindor into a shocked silence when he loses his temper with them and delivers a furious "The Reason You Suck" Speech. As the narrative points out: "This was Neville Longbottom. Neville Longbottom did not get angry and start yelling at people. It was like a natural law had just been broken or something."
In Through Thick and Thin, chapter 4, when Ryuuko ties a red a ribbon instead of the usual blue one, Satsuki immediately thinks that the former's illness (subtly implied to be cancer) has begun to hit terminal.
In the sequel, Piano Notes, what gets Ryuuko to visit a critically ill Satsuki in the hospital is that she heard the latter's voice call her "Ryuuko", instead of "Imouto", like she normally would. Earlier in the fic, Ryuuko comes home to find her not at the piano for their lessons but, instead, resting in bed, having grown tired and weaker from her illness
In Odds and Probabilities, a prequel to the aforementioned Through Thick and Thin, Mako mentions that Ryuuko normally wouldn't admit she was scared and would say "Hell no!" or "No way!" and laugh it off, so when the latter doesn't do that, it tells her how sick Ryuuko is.
Dumbledore is generally a polite and friendly old man who will generally just sternly warn someone when they go too far. So it says just how tired he is of Snape's prejudice against Harry in Heir to Zod when he essentially tells Snape to shut up before Dumbledore makes him shut up.
Given that Tabitha only rarely shows emotion and never raises her voice, it shows just how furious she is in Soldier of Zero that she's driven to murderous rage at the revelation that her mother has been poisoned regularly for the past few years (Tabitha thought she'd been poisoned once saving her life). Saito has to tackle her to the ground to keep her from killing her staff until she finds the traitor.
Peeves is universally unhelpful and antagonizing (befitting a poltergeist), but he's still willing to help in The Werewolf Conspiracy; he opens a locked door which had been preventing several students from helping a group being attacked by werewolves and asking Harry to once more defend Hogwarts.
Blaise Zabini realizes the attack was planned after Malfoy's sole reaction is to say it's a shame Daphne had to die since she was quite the looker. Ordinarily, he'd have been ranting about filthy half-breeds daring to lay a hand on a pureblood.
Given that Kirche always refers to Ranma as "Darling" in Zero Interface, Louise realizes something seriously wrong and/or bizarre must have happened when Kirche responds to her questions with a simple, "We're going to find Ranma."
Gai in Desperation Attracts Vultures shows just how far out of line he thinks Neji is for his behavior, when he insists that Naruto report Neji for attacking him twice outside of the exam - which is grounds for immediate disqualification.
Lydia gradually cottons on to the fact that something's really not right with BJ when he tells her to go home and never come back, in Cinderjuice. It does take her a little while to understand this, since his hostility triggers a brief Heroic B.S.O.D. for her, but it's so unusual for him to not want her around that their friends are also very confused.
In Kill la Kill AU, whenever Rei, aptly called "the Drunk Secretary", doesn't drink - or rather, stops drinking (as is the case in Room 002108), it is a sign of something very wrong. Likewise, it is considered odd when she's actually coherent and talks as such.
In Thousand Shinji, when Touji and Kensuke see usually stoic and emotionless Rei Ayanami smiling and acting giddy, they get scared and wonder what Shinji has done to her.
“Toji... are my glasses busted or is Rei running towards us? And smiling?” Kensuke asks rather worriedly. “She is,” Toji answers fearfully. “I’m... I’m scared. Hold me Toji,” Kensuke asks. “Only if you hold me back,” Toji demands and the two of them grip the other in abject terror.
Wonderful: When Taylor says to Sophia's face that they shouldn't put up with her crappy attitude and Sophia shrugs her off, their teammates wonder if she's been brainwashed or mind-controlled.
“Can you speak louder Red? I barely heard that!” “I said to NOT PUT UP WITH ANY OF YOUR SHIT!” Taylor yelled back as Vista’s eyes widened. Her eyes widened further as Sophia called back. “Got it!” “… OK, that’s a bit freaky.” Kid Win spoke up, looking between her and the room where Sophia was in. “I feel like I should be calling Master/Stranger protocols just about now.”
Quicken: When Danny gets angry as he mentions that Taylor was hospitalized after a bullying-related incident, Emma is shocked and a bit frightened because he's the mellowest person she's ever known.
I was startled to see his face reddening with what looked like intense rage, a fury comparable with what I had displayed before, with all the shit I had dealt with. It passed almost instantly, but it had surprised me all the same. Mr. Hebert was the most mellow, low-key person I had ever known. I hadn’t even thought it was possible for him to be angry, let alone to this extent.
After taking him prisoner in Reaching for a Dream, Naruto found it immensely odd that every so often Hidan would say he wanted to die. After Jashin possesses Hidan and Naruto kills him, Hidan calls Naruto an asshole and thanks him as he dies. This causes Naruto to realize that Hidan's requests to die were likely his only lucid moments, when he realized something was deeply wrong with his body and soul.
Regularly in Team 7's Ascension: Blood Wings, one of the characters does something off to show how different they and/or the situation is from the norm. After eight weeks in the Forest of Death, Naruto spends several days barely talking at all, having not spoken a word in the forest until he met up with Sakura. While in the capital, Sakura keeps hugging herself to keep her hands near her hidden weapons, regarding everyone not on her team as a potential enemy. Likewise, Sasuke kept his hands in his pockets where he could hold shuriken unobtrusively. Lastly, any time Kakashi goes easy on his team, either he's about to make their training far more brutal or he's got orders from the Hokage that interfere with his plans.
Lampshaded in Breath of the Inferno when Dumbledore's and McGonagall's search for Harry Potter brings them to an abandoned Goblin Gold Cave. Given that goblins will literally wage war over a single stolen piece of goblin property, both are terrified of the thought of something that would make them abandon one of their underground palaces filled with mountains of gold, silver, and precious gems. Said something turns out to be a dragon of Smaug like proportions and power.
In White the other Sternritter warn Yuzu to be cautious around Giselle whenever she stops acting cutesy and starts acting more lucid and paranoid as that's when she's the most dangerous. Turns out her cutesy behavior is just an act and her paranoia is because she wants out of the Sternritter but doesn't know who to trust.
This happens multiple times in Pokemon Opal And Garnet. In Chapter 7, "Esmeralda Takes Flight," Kaylie's Pokemon are genuinely concerned when their Trainer, a Genki Girl, falls into a depression. The reason? The next day will be the tenth anniversary of her father's death from cancer.
In Chapter 4, "An Evolutionary Justice," Kaylie is stunned when Quasimodo, who is just as shy as the Disney version of his namesake hunchback, decides to battle an opponent. Usually, he would run away.
In "A Very Rocky Start: Part One," when the normally bold and dedicated Rocky is suddenly seen quivering in fear at the sight of his abusive father, you know just how much abuse his father has been giving him. As it turns out, he's been doing illegal things- including burning Rocky with a Flame Wheel move- to his own son!
Even more than the forming lynch mob, Apple Bloom shows how dire the situation is in The Man With Two Names when Lucky frames Jeremiah for attempted murder. When her friends exclaim that she's earned her Cutie Mark, she urgently yells that it doesn't matter right now.
Oversaturated World: After the pony Mane Six defeat Starlight Glimmer, Discord pops in and cuts off his own banter to get them back to Twilight's castle as quickly as possible. Even he is worried.
In Wagging Tail Ashikabi, Sirius Black spends twelve years as Padfoot and drunk off his ass. But when he spots Wormtail in the paper, he becomes Sirius for a short time and books a flight for him and his Sekirei Kazehana to England. On the way, she concludes something is seriously off when she realizes Padfoot is sober for the first time in the roughly twelve years she's known him.
Each of the future Straw Hats in The Dream act considerably different than normal after being knocked unconscious or in a coma. The reason being that unlike when they sleep, they don't go to the dream world with everyone else, but instead are stuck in a black void where they can't move, hear, sleep, or see. Afterwards, Luffy is always clingy, Zoro stays close to everyone, Sanji becomes more obedient, etc. Despite not knowing about the Blackness, Zeff is notably confused how Sanji went from wanting to kill him to being completely obedient after being knocked out.
A Brighter Dark. Pretty much any time BrighterDark!Corrin is shown taking anything seriously or reacting to events outside of her usual loud, violent nature, you know something serious is going on with her. Most notably is when she's trying to convince her father to spare an enemy. Despite being fully willing to kill them herself, upon realizing that they were family of one of her closest friends, she becomes so increasingly desperate to sway her father that she actually gets down on her knees and begs.
As big of a Determinator as he is, Ranma finally reaches his breaking point in Hell is a Martial Artist after the failed wedding when he realizes Akane still doesn't trust him and so long as he's cursed, will always consider him a pervert. On top of that, his mother all but states she won't truly accept him as her son unless his curse is cured. Hild later finds him in her office crying his eyes out.
Queen Of Shadows: The Generals are so shocked by Jade/the Queen "birthing" Hishu that among other things, Sanshobo drops his Large Ham tendencies and starts talking and acting like a normal person. The others find it disconcerting.
Robb Returns: Eddard Stark asking about legends? Something must be seriously wrong.
A long lull in the fighting against the Vale clans is enough to make the Blackfish worry. When all the clan leaders arrive to the Bloody Gate, he realizes it might be worse than he thought.
The Company of the Rose, formed by the descendants of those Northmen that chose exile over bending the knee to Aegon the Conqueror, seeking passage to the North? That's a red light for sure.
Played for Laughs: When Baelish demands to be tried in front of his peers, Stannis replies that weasels cannot speak and are not allowed in trials. Jon Arryn is quite shocked at the fact that Stannis actually made a joke.
Many in the Seven Kingdoms are surprised when they learn that Robert has suddenly started to become more active.
In Chapter 25, the normally courageous and manly Boss scouts underwater after Soundbite drives off a giant octopus, and promptly jumps back on the ship shouting that they have to leave now! Turns out a giant tortoise (large enough to have an entire city on its back) was surfacing under the Going Merry.
Cross manages to cause two in Chapter 26, one without even realizing it.
First he breaks Robin's facade as The Stoic by telling her he'd explain his otherworldly knowledge when she tells the crew about the day Ohara died.
Second, during his SBS broadcast, Cross speaking out against the inhumanity of slavery and the evil of the Marines for allowing it causes Boa Hancock to declare him and anyone associated with him to be exempt from Amazon Lily's Lady Land law.
Terry drops his usual serving of Large Ham when he and Isaiah tell the Shandians exactly what happened to Jaya and Shandora.
Played for Laughs in Chapter 31 when Nami is so ecstatic over getting an entire pillar made of gold that she not only agrees to give massive amounts of money away, but even lets Cross take some tangerines from her orchard. However, she still won't forgive Zoro's debt.
Cross convinces her to set aside most of the gold after he explains the gravity of the Going Merry's situation, namely that Merry simply wasn't built for the Grand Line and is currently dying from the damage that's built up.
In Chapter 35, Luffy goes back on his hatred of spoilers and tells Cross he can reveal anything he wants if it'll help them get stronger.
How serious is Garp recognizing Baron Omatsuri from his glory days? Serious enough to make Akainu falter.
Even though none of the Straw Hats realize it themselves, everyone listening to the events of the SBS as they unfold with Baron Omatsuri can sense something's wrong as the crew's bonds slowly fall apart.
The transmitted horror that is Lily Carnation has even stoics like Basil Hawkins in flusters and Jewelry Bonney devoid of her appetite.
And the aftermath of Baron Omatsuri's attack has Garp calling and telling Luffy that he's So Proud Of Him, and Sengoku offering Luffy a Warlord position, knowing it'll be refused, and even showing a hint of respect.
The Rin Okumura from Veränderung does Exorcist work in freelance and knows his demonic lore pretty well, and he finds outright creepy Astaroth's reaction to his blue flames. Because demons are supposed to be swearing and trying to rip your face off, not calling you their young lord and show you reverence.
In The God Squad, if Shining Armor's first response is violence, then you know you've screwed up.
When Tydal tells Chrysalis and Sunset to run rather than help him fight Tirek, Sunset instantly realizes something is VERY wrong. Tydal knows he can't win and knows he is going to die. He told them to run so they'd at least survive.
Harry Potter dropping his Immortal Immaturity and becoming serious in I Still Haven't Found What I'm Looking For, things have become serious. After rescuing a group of slaves, he drops all his innuendo towards Aayla Secura and wearily tells her to get the hell of his ship. Several chapters later, Harry and company head towards an unknown blockaded system that might have Sirius Black on it. Once Harry gets a good feel of the place, he stops joking and outright scowls as he tells the others that someone has been blurring the line between life and death there.
Lovehammer Inc has the Primarch Angron as a large ham who has no indoor voice, a broad violent streak and poor impulse control. Planets have surrendered at just the suggestion he might be sent to invade them, so brutal is his reputation. The one time he actually lowers his voice, his equerry Kharn (who has worked for him for centuries) notes that even he's NEVER heard Angron sound so bloodthirsty.
In Chapter 29 of Origin Story, Tony Stark, Alex Harris, and Natasha Romanov have what is effectively a strategy session while the two women are sitting topless, sunbathing next to the Black Panther's swimming pool. The fact that Tony Stark isn't ogling the hell out of the naked women is a sign that he's taking the situation much more seriously than he normally takes any situation.
In Chapter 2 of Luan's Problem, Luan Loud's silence and morose behavior is immediately worrying to her mother and Rita doesn't believe her daughter when she claims she's fine.
In spite of a glamour preventing people to guess anything relating to Ladybug and Chat Noir's identities in What the Cat Dragged In, Natasha manages to peg them as teenagers after remembering Tony Stark didn't even try to flirt with Ladybug, since he subconsciously knew she was underage by American standards.
In All This Sh*t is Twice as Weird, it sends a shockwave of surprise through the entire court at Skyhold when Victoria not only sentences Erimond to death, but wants to carry out the execution herself. Mahanon has to intervene because he realizes just how much this will damage her if she goes through with it. It's all related to her Crisis of Faith.
In Xendra, when the titular character puts on her Xena gear, it quickly becomes apparent that Dracula's mind control wasn't neutralized like the Scoobies thought. Instead of her sports bra and flat sole shoes, she grabs her best push-up bra and four inch heels and neglects to don the heavy panty that goes with her outfit. Sure enough, she and Buffy are still mind controlled and head straight to Dracula after getting ready.
In Black Sky, a pissed off Xanxus will throw his subordinates out of the window, burn the furniture and snarl. A truly irate Xanxus will go silent and later explodes in a spectacular fashion, Cradle Affair-style.
In Chapter 3 of the spin-off, Parenting is not a Varia Quality, Tyr knows that his partner Mainomai doesn't like jewellery at all. When he sees the guy outright admire a heirloom necklace, he immediately understands something's fishy and prevents Mainomai to put the necklace on. Good thing he did, because it held a nasty Curse.
In Neon Genesis Evangelion all the pilots essentially mutiny when they learn of the nude sync test coming up. All of them refuse to participate in what Asuka calls a degrading experiment of no actual benefit. When Ritsuko tries to force them to go through with the sync test, including suspending Asuka, threatening Touji's sister (who receives medical care from NERV so long as he pilots), and trying to physically attack Rei, Shinji enters a state of Tranquil Fury and Rei lashes out at Akagi with her AT-Field.
In Biology Say What every member of the board of the New Watchers Council has the right to issue a formal request/order for a change of policy that can only be overturned by a unanimous vote by the remaining board members. Giles is shocked when Xander utilizes his right for the first time ever after meeting a slayer who was noted as being a real problem child. Xander calls for a female social worker, preferably one with nurse training, to handle all intakes from now on and all intakes of the previous year to be reviewed, after learning the problem child slayer had been sexually abused.
Despite almost everyone reviling Lelouch as the Demon Emperor in Entropy, when Chiba tries to insist Lelouch didn't even care who killed his mother, everyone present backs up Nunnally when she coldly demands Chiba apologize.
In The Tempest, when faced with Discord’s return, Burro Delver only realizes how serious the matter is when he realizes that Celestia is worried.
Celestia was worried. They were all going to die. Probably while screaming and on fire.
Later in the same story, Celestia snaps and angrily chews out the other world leaders for never putting aside their pettiness and power hunger, even when in a Discord-made magic cage hundreds of feet in the sky and powerless in every way that matters, stating that she seriously considered taking over the world on past occasions when it seemed like the only way to get everyone to act civilly to each other. Everyone else is rightly freaked out.
When Major Jennifer Hailey openly freaks out at seeing the corpse of Harmony Kendall in Xander and Yet ANOTHER Demon, Carter figures out something is seriously wrong and correctly guesses the girl has some unconfirmed intel she didn't share. Hailey figured out that vampires exist and recognizes that if Harmony is in that good a condition after seven years, she must be one.
Asuma is a very laidback and easygoing man in Black Flames Dance in the Wind: Rise of Naruto with Ino noting she'd never even seen him angry before. So his utter rage at the fact she was throwing live steel in a training ground really drives home how much she fucked up, especially as a similar incident before the village formed caused a blood feud when a kunoichi's shuriken accidentally slit the throat of another ninja.
Hana notes to Tsume that Kiba hugged her and said he loved her that morning, something he hasn't done since he was eight. The end of the chapter reveals Kiba killed himself later that day.