In the novels, Itsuki creates one to give Haruhi a foil and thus something to do. It quickly gets filled with members of at least two of the factions.
It's inverted before that, for the first half of the year, with the student council taking no action against the SOS despite their occupation of the Literature Club room and occasional other disruptive activities.
In Disappearance, Haruhi claims she's from the "Student Council Information Division" to convince Asahina to go with her. Invoking the name of the Council is persuasive, as is dragging Asahina away when she hesitates.
Adam and Eve Plot: Brought up by Koizumi at the end of the first season. Kyon is not amused.
Adaptation Dye-Job: An interesting case. In the original novels, Mikuru had chestnut-brown hair, Yuki had flat-gray hair, and Haruhi's hair was black. In the anime Mikuru's hair became bright orange, Yuki took up a few shades of purple, and Haruhi's hair became brown. But after the anime's release, in the later novels, Ito starts to use brown hair for Haruhi (though she retains Mikuru and Yuki's brown and gray).
The Disappearance of Haruhi Suzumiya has some shades of this as well. One notable example is Kyon's choice of "normal world vs. paranormal world", which was only about two pages long in the novel, but was expanded into an inner-conflictesque scene that lasted at least a good five or six minutes.
Cleverly played with. At first, it seems pretty obvious that Kyon is our Scully, and Haruhi is our Mulder. However, Kyon just keeps running into too much weirdness to deny that any of it exists, and by the end of Disappearance, he's become a willing, full-blown Mulder who is more than happy to do what he can to keep his friends safe by confronting all the weirdness in his life — and he openly admits he wouldn't have it any other way.
Meanwhile, with Haruhi... Kyon eventually confronts Haruhi over the fact that there really is a time traveler, an alien, and an esper in her club. Her deep-rooted cynicism, however, prevents her from even vaguely taking Kyon at his word.
All There Is to Know About "The Crying Game": Even without having ever watched/read/anything Haruhi Suzumiya, thanks to this series' raving fandom, it's pretty well known in anime communities that Haruhi is an omnipotent god; ironically, this "fact" is actually Fanon.
Alternate Timeline: Beginning in The Dissociation of Haruhi Suzumiya, the narrative splits into two parallel timelines (which Koizumi later designate as timelines α and β, respectively): α starting off with Kyon getting a call from an unknown girl, and β with Kyon getting a call from Sasaki. Accordingly, the concurrent stories begin to snowball as the conflict rises, until ultimately being reunited by the end of Surprise.
The subject of Disappearance, at first glance. It's actually the same universe with a different timeline.
While Haruhi wants to meet a slider, Kyon has stated that this is the one type who offers no advantages. So far he wins.
Alternate Character Interpretation: In-Universe this shows up a couple of times in Kyon's conversations with Koizumi. For example in Astonishment they debate whether Haruhi's unwillingness to be late is about making Kyon wait or simply about arrogance.
The anime practically revolves around this, with in-joke references to events that have transpired but that aren't shown until later episodes — for example, having random items lying around the club room that are obtained in later (earlier?) episodes. Several episodes in the first season even include set-ups from earlier events whose episodes didn't get animated until the second season. Not as hard as it sounds, since the novels were written before the anime, but still shows very remarkable attention to detail on the animators' part.
"The Rebroadcasting of Haruhi Suzumiya" mixes old and new episodes (including Episode 00) in the order that Kyon experiences them — chronological for the most part, but not in every instance. Thus the so-called "second season" is, strictly speaking, neither a sequel nor a prequel to the first, but more of an "interleafquel".
The novels include this as well, though to a lesser degree (1, 2, 4 and 7-9 are in chronological order, 3 takes place between 1 and 2, and the stories in 5 and 6 are scattered between the end of 3 and the start of the main storyline in 7).
Also Haruhi is prone to making throw away lines whose real meanings are found on the other end of a time trip.
Anchored Ship: The Love Dodecahedron seems to come down to this. (1) Haruhi likes Kyon. (2)And will subconsciously rewrite the universe out of jealousy. Kyon won't admit his (very apparent in the later novels) feelings for her and the second points keeps anything else from happening. Everyone seems more or less ok with the current situation also.
And I Must Scream: "Endless Eight". Yuki, who is supposed to be an Emotionless Girl (or at least really, really bad at expressing herself), is shown to be visually bored and possibly sad from having to re-live the same two weeks over and over again for over 595 years worth of time. (This reaction from her is comparable to a screaming hair-tearing fit from anyone else.) She's the only one who realizes that they're looping and she can't do a thing about it because her job is to "observe." Thankfully, for the viewers it's (only?) 8 episodes. Even more thankfully, for those that read the books it was only a few pages.
Annoying Younger Sibling: Kyon's little sister, to him at least. Everyone else seems to think she's adorable, but then again, that's how it often works out in Real Life.
Apocalypse How: The possibility of Haruhi having a bad day and unconsciously recreating the universe, or a certain someone hijacking Haruhi's power. The former seemed to be creating a new separate universe rather than rewriting the old one.
Arc Words: After a point, it starts to seem like every past-tense sentence in the Myth Arc contains the words "three years ago." Eventually subverted when Itsuki starts a sentence this way, and Kyon interrupts him with "Screw three years ago!" Dissociation takes place a year after Melancholy, so the Arc Words have appropriately changed to "four years ago."
Artifact Title: For the anime at least, which takes the name of the first book. Those who haven't read the books will wonder why the show is called The Melancholy Of Haruhi Suzumiya, when she's anything but.
Aww, Look! They Really Do Love Each Other: Despite arguing every other minute, Haruhi and Kyon are shown to care for each other. Any nagging doubts viewers had were killed by the movie. Kyon wakes up after spending three days in the hospital to find Koizumi, who tells him that the Brigade members have been taking shifts watching him. Haruhi, however, is curled up in a sleeping bag next to his bed, where she has been the entire time.
During the fight between Yuki and Ryoko, Ryoko dashes at Kyon with full force, blade extended. Yuki halts her charge by grabbing her combat knife by the blade. Subverted in that she takes visible damage.
Played straight by Kuyo Suo.
Bavarian Fire Drill: "Which one of you is Mikuru Asahina? Hi, I'm Haruhi Suzumiya, from the Student Council Information Division. Please come with me!"
When the Data Overmind considers erasing Yuki in Disappearance, Kyon threatens to reveal the entire Masquerade to Haruhi and have her rewrite the universe to save Yuki.
Then when the Sky Canopy Dominion incapacitates Yuki in Surprise, Kyon storms off to confront their interface. Alone. And unarmed. It takes Asakura to save him, and even she only manages to fight Kuyo to a draw.
Considering how Haruhi reacted to Yuki's "illness", she is probably already very similar to Kyon in this aspect, towards the whole SOS brigade.
And a different button: When Haruhi's abuse of Mikuru went too far and he was willing to punch her. Let's be clear, he was willing to deck GOD because she was being a bitch.
Kyon finally snaps and actually tries to punch Haruhi after she takes her abuse and assumed ownership of Mikuru too far during her movie's filming.
Mikuru is kind, sweet, and an utter doormat who is forcibly stripped and dressed up in various costumes by Haruhi, and who is given strict directives she can't understand from her superiors in her time travel organization. The most Mikuru ever manages in response is a high-pitched, desperate "noooooooo!" You may be surprised to find that she has a character song about her wish to have revenge on those who have used her as a toy and a pawn. And let's not forget the morally dubious things her future self does...
Sasaki claims she's an example of this, that she gets angry every few years and "It scares even me," but we don't actually see it.
Yuki saving Kyon from Asakura. And later Emiri (another Human Inteface) joins the fight between Suo and Asakura. It makes you wonder if basic training to be an extension of the Data Overmind includes learning how to pull this off.
Also Kyon does it for himself! Well, actually, it's Yuki again, but he does organize the rescue.
Bland-Name Product: Espon laptops, Sicao cameras, Kyon's Pumu bag, and the characters eat at WcDonalds and at a WOLKS family restaurant (inspired by VOLKS). Also done with brand logos: one episode shows a box with a logo shaped like an unbitten apple.
Kyon is this and Cursed with Awesome for the largely the same reason. Pretty much everyone tells him that he has been "chosen" by Haruhi, but what this seems to entail in practice is that he is her Butt Monkey.
Kyon eventually decides he has been blessed with awesome in the movie.
As the novel series has continued it has been hinted that Haruhi herself is entirely an innocent victim of Cursed with Awesome that Kyon has imposed on at least two instant goddesses.
Koizumi, it is cool that he can go into some other realm and use lasers to kill giants, but he can only use his powers in that other realm, and he can't do things other espers from other series can do like read minds or levitate.
"Blind Idiot" Translation: There's a bit of this in the dubbed anime, where the Japanese honorifics are translated into Miss or Mr. X when referring to classmates, but this is because most Japanese honorifics really don't translate to anything in English and leaving them in can be very confusing for people unfamiliar with the complexities of the Japanese language.
Kyon, too. Only its Blunt Simile Trauma: "Haruhi's endorphins ran through her brain like a hamster in a wheel at Mach 3", "the Celestial in Haruhi's Closed Space glowed blue like a luminescent fungus" and so forth.
Book Ends: The second season ends with the screening of The Movie that opens the first season.
Boomerang Comeback: Ryouko uses this technique with her knife against Kuyo Suo. It doesn't work.
Bowdlerize: "Remote Island Syndrome" is changed from the book through the addition of Kyon's little sister, who in the novel attempted to come along, but was discovered and left at home. Once on the island, the SOS Brigade members avail themselves of as much alcohol as their host can muster, which can't be shown on Japanese TV, since the characters are still in high school. The TV show has them doing things appropriate for the presence of a grade-schooler instead. Minus the murder-mystery part, anyway. Though understandable, if you only watched the anime, it will cause a bit of confusion for the Disappearance movie. The movie is extremely close to the original novel, and even keeps Haruhi's line that went something like, "I'm never going to drink again." As she never drank in the anime in the first place, this creates a bit of a Noodle Incident by Plot Hole. The dub of the movie simply skirts the issue by having Haruhi say that she swore she would never drink ever in her life. (Which, according to the anime, is accurate.)
Bread, Eggs, Milk, Squick: Asakura complains about how Haruhi is not doing anything interesting and talks to Kyon about whether or not it is all right to enact a change to get a result, even if it is dangerous, right before trying to stab Kyon with a knife to get a rise out of Haruhi — all without changing the pitch in her voice.
Bug Catching: Competitive cicada catching is one of the Endless Eight activities. Though, as Kyon points out, this is a weird activity for kids their age.
Butt Monkey: Sometimes Mikuru, sometimes Kyon, and always the poor, poor Computer Club President, though he's closer to The Chew Toy, as his endless torment is meant to be funny.
Call Back: The scene where the Brigade finally reunites in Disappearance is comically similar to their original meeting in Melancholy. The Stinger also features Yuki watching a little boy help a little girl get a library card, just like Kyon did for her. Mikuru's entrance into the Clubroom was practically exactly the same as her original entrance in "Melancholy".
Call Forward: ENOZ can be spotted in the first episode of Sigh.
Can't Get Away with Nuthin' : Averted by Haruhi, whose main specialty (considering the non-awareness of her own powers) seems to be beating this trope to death and beyond.
Can't Hold His Liquor: Oh, man, Mikuru. It's worse in the anime, where she passes out after a bit of amazake (which is so weak you can give it to children) she was slipped for some Enforced Method Acting. Slightly more justified in the novel, where it's tequila, and in the dub, where they change it to sake.
Cassandra Truth/Sarcastic Confession: Kyon outright tells Haruhi that Itsuki, Mikuru, and Yuki really do have supernatural powers. Twisting Genre Savvy, she smiles sweetly and correctly guesses who has which powers — then promptly yells at Kyon for mocking her before storming out.
Mikuru — "Classified Information." Taken to absurd lengths in "EndlessEight": "I used classified information to contact the future or for classified information... But when I hadn't heard from classified information for a week I thought something was wrong. And then classified information... I was so shocked that I classified information, but there was no classified information... What should I do?" All while crying her heart out. It's a compulsion deliberately put into place by her superiors to prevent her from divulging sensitive information, even if she wanted to. Normally, she just avoids using the taboo words altogether, but here the mechanism repeatedly trips because she's too emotionally vulnerable to watch what she's saying.
Haruhi — "I'm so bored!"
And then of course there's Kyon's "Yare yare" (translating to something like "good grief"/"oh my"/"oh well"). Sasaki said it first, and Kyon picked it up.
In the DVD's previews:
Yuki: Watch it.
Lampshaded and subverted — in the first episode, Kyon notes that Haruhi has a habit of saying "totally", but the audience doesn't hear it enough for it to qualify as a Catch Phrase.
Cats Are Magic: Shamisen, the calico cat. He (male calico cats being extremely rare) originally started as an ordinary cat, but was briefly given the ability of speech. This was because Haruhi believes witches need magical cats, and this belief altered reality and made Shamisen magical. She never finds out that Shamisen could talk, but was originally a little disappointed that he wasn't a black cat.
Also by Yuki to Kyon in Disappearance when he was about to leave her to have dinner alone with Asakura.
Caught with Your Pants Down: A double entry when Kyon was closing the pictures of Mikuru's chest with star-shaped mole: He forgot to close the folder named "Mikuru". He also neglected to name the folder something other than the obvious "Mikuru".
The novels are primarily focused on the character development. It is often left to the readers' interpretation just how far the characters have changed within the progress of the story.
Best example, Yuki Nagato: From a stoic "machine-like" Extreme Doormat, to a person who is not only kind and caring, but also independent from her boss. Hell, her rampage in Disappearancebecause she developed feelings must not be forgotten. Furthermore, the relationship between her and Kyon gradually expands over the time, to the point where Kyon stated that no one would "shake the bell in him" quite like Yuki. Nagaru Tanigawa himself stated that he likes focusing on Yuki's development.
Haruhi: From a self-absorbed, misanthropic loner, to a cheerful and hot-blooded, yet still quite sociopathic jerk who doesn't really get what she's doing wrong... Eh, well, see Kick the Dog. Then, in the later novels, she has become far more sociable, even to strangers, and generally has come more to terms with "this boring world" (and has come Out of Focus).
Kyon: From an apathetic, cynic and distrustful Deadpan Snarker who cares little for anyone besides "his" Mikuru and tells himself that he hates the brigade, to a True Companions-guarding, occasionally-BadassKnight in Sour Armor who freely admits that he's a member and would follow their commander Haruhi.
Mikuru: From a self-sacrificing group mascot who lets Haruhi do whatever she wants with her (Present Mikuru), to an assertive, empowered, and even morally ambigious woman who controls the situation from behind the scenes and is responsible for setting the entire plot in motion by masterminding Bamboo Leaf Rhapsody (Future Mikuru). The exact details of how this transformation takes place is somewhat sketchy (time travel is involved), but its seeds are present in some of the later novels.
Koizumi: From being a vague, mysterious representative of the Organization whose interest in the group seems purely professional, to a person who genuinely cares very deeply for the the Brigade, even stating that if he had to, he would choose the SOS Brigade over the Organisation. Which means a lot, considering he's in charge of the Organization!
Chekhov's Gun: Offhandedly mentioned objects usually play an important role later in the light novel it is mentioned in or in the whole novel series itself.
Kyo Ani is very careful about this. Objects that serve a purpose in a story are seen in the club room WAY before the second season was made (ex.- the bamboo leaf potted plant). Even more interesting is the fact that a couple of these were retroactively added to the DVD release, which weren't present in the original broadcast. This video, based around changes between the broadcast and DVD release of "Remote Island Syndrome", where one of the changes made was adding the bamboo plant to the background.
The anime's adaptation of "Remote Island Syndrome" ends with a conspicuous close-up of a mole on Kyon's neck. This is popularly considered foreshadowing toward "Snowy Mountain Syndrome", where Itsuki encounters a doppelganger of Kyon. He has to have some kind of distinguishing mark, right?
Based on a hunch, Kyon tells Tsuruya to dig at a specific spot on her property. She finds a strange artifact buried hundreds of years ago by one of her ancestors, but made with materials and craftsmanship that ancient Japan (and the rest of the planet, for that matter) simply could not have had access to. Although they don't know what it is, Tsuruya agrees to keep it, and from then on will remind Kyon to call once he decides he needs it.
Chekhov's Gunman: Seemingly minor characters, if named, will usually have some major significant role in the plot later in the series.
A rather major example would be a character so minor she isn't even directly mentioned. Sasaki, a friend of Kyon's from middle school, is mentioned offhand by Nakagawa as the precedent for Kyon "liking weird girls," which Kunikida had said in the first chapter of the first novel. She doesn't appear until the ninth novel, where it is revealed that she is the cause of that particular misconception. Once again, Kyo Ani is on the ball with this when in DisappearanceSasaki's name can be seen at the top of Kyon's cell phone address book (See Early-Bird Cameo below).
Kimidori. Tsuruya. The esper girl (though really, who thought she WOULDN'T come back up again?), Kyoko Tachibana. If they get a name and they're not Taniguchi or Kunikida, expect them to be important. Those two are probably only still unimportant so that they can be Those Two Guys... and the light novels aren't finished, so it's hard to know if it'll stay like that.
In a way, Kyon himself is a Chekhov's Gunman. To quote Haruhi's extremely inconspicuous line: "Have I met you somewhere before?" She has in fact met him before, and the encounter is what led her to North High. This is also invoked when Kyon wonders what criteria Haruhi used to pick her high school.
How inconspicious is it? In the anime, it makes sense in context of the conversation so much so that it can simply be taken as an example of Haruhi's eccentricity! (That and the fact that it's the stereotypical pick-up line in Japan...)
How many times have the characters made a point about not yet having a slider around?
There's also a really inconspicuous one in Disappearance. While reading out the class roster, Kyon also mentions the person before Haruhi, Sakanaka. Later on in the eighth novel, she appears as the second client of the SOS Brigade.
Remember Taniguchi's girlfriend in Disappearance whose absence in the Alternate Universe is Kyon's first hint that something is wrong? In volume 10, it turns out she's Kuyo Suo, the alien interface from the Sky Canopy Domain which opposes the Data Overmind. She was trying to establish contact with Kyon, but was unable to tell him apart from Taniguichi.
Cherry Blossoms: The opening of the first chronological episode. Cherry blossoms are also at the center of an important event in Sigh, when they bloom in autumn just so Haruhi can have them in her movie. Kyon is also constantly telling us the time of the year and season (especially in the novels), which often involves evocative statements about whether the cherry trees have blossomed yet, are currently in blossom, or how long it has been since the blossoms fell.
Chick Magnet: Check the audience of the play at the school festival. Who are they there for?
Childish Pillow Fight: In "Remote Island Syndrome" Haruhi is extremely good at it during the club trip. Just before the murder mystery starts, Haruhi throws one into Arakawa's face unerringly. The Mood Whiplash is quite hard, especially if you haven't read the light novels.
Cicadian Rhythm: One of the various summery activities Haruhi forces the Brigade to participate in during their endless summer vacation is cicada-catching.
Clarke's Third Law: Clearest with the human interfaces' data manipulation (Yuki is even cast as an alien witch in Haruhi's movie for brevity), but also apparent with the technology of humans from the future, where mechanical devices seem to have been phased out. Kyon also quotes the law in the narration of Melancholy when Taniguchi asks him, "What kind of magic spell did you use?"
Discussed at the beginning of Sigh, when Haruhi demonstrates that the concept of The Climax completely goes over her head:
Haruhi: There's something I've always wondered about. You often see people die in the last episode of TV shows and the like. Doesn't that feel unnatural? Why do they just happen to die at that time? It's strange. That's why I hate anything where someone dies at the end! I would never make a movie like that!
The series' plot itself seems to agree with Haruhi, The Climax happens in the chronological middle of the season, while the chronological ending is a generic filler episode.
Consequently, Haruhi's failure to drive the movie's plot toward some sort of conclusion and the consequences of it turn out to be a major plot element of Sigh.
Season 2 actually has two climaxes, since that season is split pretty evenly into two "mini-seasons."
Closed Circle: Remote Island Syndrome. Haruhi wants to do one for fun, and Izumi's esper organization obliges because they think she will be less likely to use her powers if she becomes afraid of excitement. It's invoked actually. Izumi and the Organization provided the actors, island and mystery; Harui closed the loop by providing the typhoon! Kyon even lampshades it by name.
The Brigade had specific colours for their "battle stations" when battling the Computer Club; out of these listed above, only Mikuru and Yuki had different colours. Mikuru was pink (to represent her status as a girly-girl), and Yuki was a sleek, whitish silvery-purple that wouldn't look out of place in an Apple store.
The image song albums had this first, but a few were switched around. Kyon's color is Yellow, Yuki's is Light Blue (which might have something to do with her seiyuu), and Itsuki's is Purple (The Movie's opening credits actually goes through these colors in the beginning). While we're at it, the covers also give us colors for Ryoko (Dark Blue), Tsuruya (Green), Emiri (Light Green), Kyon's Sister (Pink), and Taniguchi (Gray).
The English paperback novels are, in order: red, yellow, green, blue, purple, and orange.
Comforting Comforter: Last episode "Someday in the Rain". It's left unclear whether it was Yuki or Mikuru.
Compliment Backfire: Kyon slowly learns to talk about what he likes in general, instead of telling the Tsundere that he likes whatever she's doing at the moment.
The Computer Is a Cheating Bastard: Yuki plays by the rules when she's asked to, but has no qualms with fixing a game, computer or otherwise, to keep Haruhi happy. Of course, Yuki playing by the rules is like asking Stephen Hawking to do elementary school algebra. She's still a highly advanced lifeform capable of simultaneously controlling 20 independent units in the above mentioned game while at the same time hacking into said game, rewriting/reprogramming while said game is being played (at super speeds flipping through multiple windows), and casually carrying on a conversation.
Itsuki's favourite activity, much to Kyon's irritation. And, well...Shamisen too.
Towards the end of Disappearance, Kyon holds a good, long conversation with himself about whether he prefers a normal, quiet life, or the crazy, fun life as part of the SOS Brigade. The movie version is significantly longer, and includes mental imagery to represent Kyons thoughts.
Contemptible Cover: The Japanese covers don't have anything like tacky battle scenes featuring Chain Mail Bikinis, but they are emblazoned with large pictures of anime girls. The English translation seems to be trying to play both sides of the issue by offering admittedly rather classy and mainstream-friendly redonecovers for the paperbacks and retaining the Noizi Ito artwork for the hardcovers.
Covert Pervert: In the novels (and sometimes in the anime), Kyon is frequently filled with inner squee when Haruhi makes Mikuru cosplay. He also secretly likes how Haruhi's bunny costume shows off her curves and has a ponytail fetish.
A number of characters qualify (especially considering how many of them are hiding supernatural abilities), but the top of the list for being a formidable Badass Normal amongst the bunch is Tsuruya-san.
In The Sigh of Haruhi Suzumiya Part V, Tsuruya is seen in the background waiting for Mikuru while Mikuru and Kyon discuss Haruhi. It's unclear if Tsuruya actually heard what they were saying.
Kyon is both this and Blessed with Suck for the same reason. Despite him constantly moaning about how he wants to have an average life, his bond with Haruhi means that he probably has the most control over her powers than anyone else in the series (even Haruhi on certain occasions).
Cute Little Fangs: Tsuruya, also known by her Fan Nickname LOL Fang-tan. Played straight in that it actually gives her a speech impediment, which can be heard clearest in the school festival's restaurant speech.
The novels and anime frequently play with this. Since we almost never hear/read Kyon talking, only thinking, it is even more surprising when people reply to thoughts they really shouldn't have heard.
Made ambiguous when Kyon narrates with his mouth off screen, so the audience can't tell if he's speaking out loud or not. Making for even more ambiguity, Kyon's expressions aren't exactly opaque, so it would be quite easy for someone to guess what he's thinking and respond to that. And even if he was speaking everything aloud, Haruhi's selective hearing could steamroll right past it.
And even more confusingly, sometimes people around him reply to thoughts that were clearly not supposed to be said out loud, but without noticing the parts in the same sentence that were not addressed at them, like how much he wants to punch Koizumi in the face, or how much he adores Mikuru.
Did You Just Flip Off Cthulhu?: In Disappearance — Kyon vs the Data-God that created Yuki. Kyon wins, by simply pointing out that he knows how to end the world with 4 little words: "I am John Smith." The official translation gives it a whole second level of defiance.
Before that, Kyon saves the universe by kissing Haruhi... which would make this something more like "Did You Just Make Out with Cthulhu?"
Kyon comes within a hair's width of this when Haruhi takes her abuse of Mikuru too far.
Dispense With The Pleasantries: Remote Island Syndrome, Haruhi starts out extremely polite to the owner of the mansion. He then mentions that he's rather surprised since he has heard she's rather... direct. At this point she dispenses with the pleasantries and launches a barrage of questions about how many mysterious events, murders, etc. have taken place there.
Disturbed Doves: Sigh. They actually started out as ordinary pigeons, but changed to match the trope after Haruhi invoked it.
For a girl as smart and generally talented as she is, Haruhi is capable of being incredibly dense at times.
The Day of Saggitarius showed that Haruhi is no Patton — she puts so much emphasis on being Hot-Blooded that she seems genuinely perplexed and irritated that "All ships charge!" is not an adequate strategy to win a tactics-based computer game.
Divine Date: According to Itsuki, and others, Haruhi really wants to do this with Kyon. But she won't admit it, and he won't believe it.
Does Not Like Men: Haruhi at the beginning, though she mainly doesn't like humans in general. Half of the time she barely acknowledged that men exist, or that there's some difference in social behaviour between boys and girls.
Double Standard: There is a big difference on how Kyon treats Mikuru, and how he treats Haruhi. Also, Haruhi is way nicer towards Itsuki than to Kyon, and never gives Kyon credit for what he does, but congratulates Itsuki for everything. Bamboo Leaf Rhapsody provides examples on the two cases.
Subverted: Narrator Kyon implicitly threatens violent retaliation when Itsuki seems about to act out this trope with Mikuru in their film, as far as the viewer knows. Behind the scenes, he nearly does carry out this threat against the person he holds responsible for it. It's not Itsuki.
In a Season 2 episode Mikuru takes Kyon back in time 3 years, then promptly loses conciousness. Then Future Mikuru shows up to give Kyon a mission, saying she put her younger self to sleep because she didn't interact with herself in her memories. Kyon asks if he gets a reward for carrying out the mission, future Mikuru suggests that he can steal a kiss from her younger, unconscious self as reward. Try not to think about it too hard.
Dynamic Entry: Haruhi gives the Computer Club president one with both legs at once.
Arakawa (the butler from Remote Island Syndrome), appears as the cab driver in episode five of Melancholy. Because of the Anachronic Order, though, this appearance was actually broadcast after RIS.
Sasaki's name (佐々木) can be seen at the top of Kyon's cell phone address book in the Disappearance (here◊ and here◊)
Easily Forgiven: While it could be argued that Haruhi managed to avoid crossing the Moral Event Horizon, Kyon still forgives her a bit too easily after she drugs Mikuru and he almost punches her for it. Granted that this was her beginning path towards Character Development and he partially did it to avoid the universe being destroyed, it is still aggravating considering how she didn't even apologize for what she did.
Egocentric Team Naming: Haruhi's SOS Brigade doesn't look like this... until you expand the acronym and find that the second S stands for Suzumiya.
Elemental Rock-Paper-Scissors: Haruhi gets three of the four types she wishes for and usually missions will require the powers of multiple types.
The goddesses are strategically as important as Kings in the game of chess and as tactically useless.
The data entities are the strongest in tactical combat, and can dominate the environment like a Queen in chess, but are unable to effectively coordinate with each other, have limited social skills, and can't heal closed spaces.
The espers hunt in packs and their ability to enter and heal closed spaces resembles knight moves in chess.
The time travelers can rapidly advance or withdraw, but like rooks in chess they have limited flexibility once deployed and can get trapped.
And ordinary human beings are pawns that get in the way of the others, but Kyon seems to be getting dangerously close to the final rank.
Yuki Nagato, which is somewhat justified by the fact that she's a computer program. Sort of. There are a few hints dropped to suggest that she isn't devoid of emotion, but rather she's just really bad at expressing them. The other constructs that have shown up didn't seem to suffer emotional constipation in the way Yuki does, suggesting they all have emotions, or at least can ape them convincingly.
By Disappearance, she's had enough Character Development to show visible sadness, surprise, and gratitude when Kyon places her under his protection from the Data Overmind.
In Snowy Mountain Syndrome, which takes place immediately after Disappearance, at one point Yuki displays what is best described as loneliness.
Do NOT let Haruhi direct you in a movie, she's worse than James Cameron. She will resort to extreme measures to get you to do what she wants you to do, including everything from getting her star drunk so she can't protest against doing stuff she'd normally never do to subconsciously giving you lethal eye beams right in the middle of a scene
Haruhi likes Kyon, no matter how deep in denial he is about it. This is so obvious that alternate!Itsuki in Disappearance can tell just from Kyon's cursory explanation of how things were back before the world-switch.
Sasaki figures it out immediately when meeting Haruhi. She then teases them about it.
Eye Beams: In Sigh, Haruhi keeps coming up with colored contact lenses that each have a different type of eye beam. First is a laser, second is some sort of Razor Floss; Kyon states there are a few more, but the one we're shown shoots large metal spikes. The official English translation mentions four contacts: the blue, for Mikuru Beam; the silver, for Razor Floss; the gold, for the spikes up above; and the green, for miniature black holes.
Eyelid Pull Taunt: The final shot of "Someday in the Rain." This is actually a nice reference to the cover of volume 6 (The Wavering) of the light novel where Haruhi is doing just that. Volume 7 (The Intrigues) features Mikuru, and volume 8 (The Indignation) has even Yuki getting in on the gag.
Eyes Always Shut: Itsuki, and in some cases, Kyon, as seen in The Day Of Sagittarius.