To a somewhat less comedic effect, Kenny Ackerman shouts out "bang bang", "ping ping", and "clash" when getting into a gunfight with Levi.
Scared of What's Behind You: In the first episode/chapter, Eren and Mikasa go to save Armin from some bullies. The bullies prepare for a fight when they see Eren, but run for it when they see Mikasa. Eren, naturally, thinks he scared them off by his lonesome.
Schizo Tech: Humans have cannons and flintlocks for ranged combat. On the other hand, they have pressurized gas grappling hooks, hi-tech blades that appear to be mated to motorcycle handles, and literal Hand Cannons that look like they use .50 BMG cartridges. This is further hinted at in the anime, which shows a very distinct difference between the technology of the outer regions (Wall Maria and Rose) as opposed to the wealthy Interior (Wall Sina). The outer regions resemble Medieval villages, while the Interior has brick streets and people dressed in clothing closer to the Edwardian or Victorian era, including pocket watches and top hats.
Somewhat justified as of Chapter 55. The Military Police keeps technology that could "threaten the king" under wraps and kills the creators. We see a man developing a revolver look up in fear and a couple about to be shot as they jump on a hot air balloon among other people being murdered by the MPs. Neither of which technology has been seen in-series before.
Screw the Rules, I Have Money!: The merchant in Episode 6 whose cart is blocking the escape route for the civilians because its stuck in the narrow passageway. The civilians try to get a soldier to arrest him, but the merchant fires back by saying he's the one who brings the food for the peasants. He also tries to make Mikasa cooperate, but she instead forces him to remove the cart so the civilians could escape.
Secret Identity: Many are listed below, under Wham Episode: Chapters 31, 40, and 42. One that isn't: Krista Lenz is actually Historia Reiss, the bastard child of a prominent and influential Noble house privy to the secrets about the Walls.
Senseless Sacrifice: Most of the Survey Corps' missions end up this way. Unfortunately, the human race is in such desperate straits that continuing suicide missions in the hope that something will pan out someday is probably more sensible than turtling behind Walls that have been recently shown to be merely delaying the inevitable. And then there's the fact that many of their most promising efforts have been intentionally sabotaged...
Shaggy Dog Story/Shoot the Shaggy Dog: The best the Survey Corps can hope for is a Pyrrhic Victory, otherwise their missions turn out like this. One mission of theirs (the 57th) collapsed in one day and failed to accomplish their goal, resulting in what remained of them limping back to the Walls to get ridiculed and verbally spat on.
Shapeshifter Baggage: Titan Shifters don't have their human bodies become their Titan, they form a Titan body around their human one which controls and is connected to the Titan but is physically separate. Where that body comes from is mystery...
Reiner all but states that there is a limit though and it is heavily implied that it is physically draining to create and use the Titan form as Eren tends to pass out or look deathly ill after using his powers
Sheep In Wolf's Clothing: Used by Armin as evidence that Eren is human regardless of his powers. Normal Titans tried to eat him in his Titan form, so that means they recognize him as being a human.
Ship Sinking: In an interview, Isayama corrected on the guidebook describing Eren's feelings for Annie to be romantic, stating it leaned more towards respect/admiration. Annie's feelings however, are left unclear.
Ship Tease: Outright statements of romantic interest are very rare. Hints that certain characters may have such feelings are significantly more common.
Jean's crush on Mikasa is one of several reasons for his hostility towards Eren.
Mikasa is utterly devoted to Eren, and blushes when Ian calls Eren her "boyfriend". Much later, she tearfully thanks him for everything he's done for her and leans towards him in a manner suggestive of an Almost Kiss. This, however, snaps him out of his Heroic RROD and earns her a promise that they'll always be together.
Eren is close to Annie, being the only person thus far to make her genuinely smile. She teaches him to fight, to which Mikasa later accuses Eren of having "special feelings" for Annie when he hesitates to fight her in Titan Form, and appears willing to give her special consideration despite his pathological hatred of Titans and anyone who assists them . In the Middle School AU, Annie's feelings are portrayed as explicitly romantic.
Petra is noted to adore Levi, and her father cheerfully talks to Levi about how he's eager to see his daughter get married. Levi doesn't take her death well.
Reiner mentally proposes marriage to Krista whenever she's kind to him, and refers to her as being "cute".
Ymir is utterly devoted to Krista, and Krista yells at Ymir for risking her life to protect her, demanding she instead take actions that will endanger everyone to save herself. During a climatic battle, they come just shy of being a Battle Couple, as Krista declares she will never fear anything as long as Ymir is with her.
Reiner teases Bertolt and suggests he should confess his feelings to Annie If We Get Through This, earning much blushing and sputtered denials. Later, Armin successfully goads a reaction out of Bertolt by lying to him and reporting that Annie is in danger.
The Spin-Off Babies, Attack! Titan Junior High thrives on giving nods to the various Ship Teases throughout the main series. These include Eren x Annie, Bertolt x Annie, Ymir x Krista, Reiner x Krista, Jean x Romantic Failure, and Mike x Nanaba.
Side material reveals that Moblit is jealous of how close Levi is to Hange, implying romantic feelings for his Squad Leader. In-series, he's shown to be very protective when Hange is threatened.
Hitch appears to have got a thing for Marlowe, asking him if he wanted to be alone with her when they're patrolling by themselves, and looks disappointed when he states otherwise.
Shirtless Scene: It says quite a bit about this series that we've only gotten one after 53 chapters of manga, and it's barely noticeable since the scene that it takes place in is horrifying, quickly nullifying the usual connotations.
Shōnen: Despite the very grim story and the violence which would normally put a series like this into Seinen territory, this series runs in Bessatsu Shonen Magazine.
One of the gag previews from the manga has Eren waking up to discover that the entire series was All Just a Dream, and that he's actually a Japanese schoolboy with Mikasa as his best friend. So basically, the infamous Episode 26 of Neon Genesis Evangelion, but with Eren and Mikasa in place of Shinji and Asuka.
More officially, Isayama stated in a blog-post that the characters of Levi and Erwin were modeled after Rorschach and Ozymandias from the American graphic novel Watchmen. Levi shares Rorschach's body type (and is referred to derisively as being small, as Rorschach is), bizarre manner of speaking and behavior, horrendous upbringing, and white scarf, while Erwin shares Ozymandias' body type, facial features, and modus operandi: Both Ozymandias and Erwin are leaders who are unafraid to sacrifice many in order to save the majority.
A very roundabout one to JoJo's Bizarre Adventure: In JJBA, there is a character named Mark, as there is one named Marco in Attack On Titan. Both are friends of a character the protagonist butts heads with at first. Both are found dead, missing large chunks of their upper bodies, with Marco being bitten in half by a Titan, and Mark half absorbed by one of the Pillar Men. Incidentally, they share the same Japanese voice actor.
While Eren reminisces (unaware that it actually happened) about killing Titans in Titan form, he smiles, claiming out loud that he will kill them all. Unfortunately, people think that he's talking about killing them. Armin's horrified reaction to it is priceless. Eren also sports several Slasher Smiles while fighting the Female Titan, in both of his fights against it.
Annie pulls an extremely creepy one when Mikasa correctly accuses her of being the female Titan. The smile itself isn't as pronounced in the anime but the unsettling laughter that preceded it achieved the same chilling effect.
In Chapter 51, Erwin of all people briefly sported one when discussing the possibility that Titans were originally humans. Levi noticed and is completely unnerved by it.
Sliding Scale of Idealism Versus Cynicism: Zigzagged. On the one hand, humanity's prospects for the future and odds of winning any victories against the Titans are exceedingly grim, and characters drop like flies, usually suffering gory nightmarish deaths. On the other hand, the protagonist is a grimly determined optimist who has vowed that he will a) kill all the Titans as revenge and b) see humanity expand to the world outside the Walled City, both of which are ideas that most of his peers consider suicidally idealistic. His optimism keeps being challenged throughout the story, one notable instance being when the 57th expedition turns out to be a complete failure and the entire Special Operations Squad, bar Levi, dies in front of his eyes.Not that it makes him give up. From the looks of things, however, it seems to lean heavily on the cynical end, thanks to the combination of the tyranny and cunning treachery by the Military Police and the cowardice and stupidity of the common people hiding within the walls, severely hampering the efforts by the Scouting Legions in saving what remains of the humanity; at one point, Word of God even stated that he originally planned for a bitter ending where every single human dies, but took it back for the fear of Darkness-Induced Audience Apathy.
The Smart Guy: Armin might be a bit meek, but is the smartest of the Power Trio in reasoning and deduction, comes up with why Titans are weak at the base of the neck due to Eren, and deduces the Colossal, Armoured, and Female Titan had to be human piloted and comes up with the most practical plans and strategies in the field.
Soldier vs. Warrior: Used within the narrative, and explicitly brought up by several characters. The enemy Titan Shifters refer to themselves as "Warriors", drawing a line between themselves and the human soldiers they oppose. On the surface, the trope is played straight with human soldiers serving the cause of humanity's survival and the Titan warriors being shown to be proud and even competitive. But then it becomes more complicated, with the lines becoming blurred as the warriors' identities are revealed. Reiner Braun best illustrates the blurring of things, struggling with his conflicting loyalties/identities. Both sides have much more in common than they would like to admit, and there is plenty of debate over what it means to be a soldier.
The Spartan Way: Military training is a 3-year process, and it's casually noted that deaths are not only common but considered just a way of weeding out those who wouldn't have survived battle, anyway. The 3D maneuver in particular is noted to result in quite a few training accidents. Cutting the ropes on recruits practicing using 3D maneuver gear is even noted to be way to weed out those who can't keep their balance when disaster strikes, since panicking will make them useless against the Titans.
Training from Hell: Annie underwent it as a child, prior to enlisting. She tutors Eren by putting him through similarly harsh training.
Spell My Name with an S: Eren/Elen, Levi/Rivaille/Revi, Erwin/Irvin/Elvin, Krista/Christa, Arlert/Arlelt/Arelet, Bertolt/Bertholdt... It would take too long to list them all.
Not to mention the various spellings of Eren's last name of Jaeger/Yeager/Jeager/Jäger etc. (though the official translation is "Yeager").
Spin-Off: Attack On Titan Levi Side Story: A Choice With No Regrets manga, which is based on the Choice With No Regrets visual novel included with the Attack On Titan Vol.3 Blu-ray. This spin-off features Levi as the main character and serves as a prologue to the main series.
Spin-Off Babies: The Middle School AU spin-off manga Attack! Titan Junior High. It is pure, unfiltered crack involving the main cast going to school with the Titans, and deals with it as a Slice of Life comedy. It gleefully parodies the primary canon, as well as including numerous Shout Outs to popular memes and aspects of the fandom. Eren still hates the Titans, but the trauma of his mother being Eaten Alive is replaced with his cheeseburger lunch being stolen on the first day of school. Jean's lovelife continues to be a joke, Annie is a blushing Tsundere, and the memetic "Moe Titan" is a reoccurring character.
Spotting the Thread: Armin can even identify the scratches and dings on Marco's 3D Maneuver Gear when he sees it in front of Annie.
Square/Cube Law: Titans are shockingly nimble despite their size because they weigh almost nothing.
The Colossal Titan also has very different anatomy, with legs proportionately thicker like an elephants'.
Squick: In-universe and out when Hange goes into explicit details of the practices of a group of human cannibals in Episode 15. Some soldiers from the Garrison even start to puke.
Stages of Monster Grief: An underlying element of Eren's characterization, as he learns to cope with his new status.
Stealth Hi/Bye: The Colossal Titan is noteworthy for this, since no one can figure out how a 60m tall monster can simply appear and disappear in a cloud of smoke. This ends up being very significant, as this is one piece of evidence that leads them to realize the Colossal Titan is a Titan Shifter with access to military training and equipment.
In the anime his appears with a flash of lightning, whereas in the manga he appears out of nowhere in the space of a single panel change
Stepford Smiler Krista Lenz as revealed in Chapter 52. Krista is the hollow type.
The Stinger: The very end of Episode 25 has a huge Sequel Hook after the credits: there is a TITAN inside Wall Sina!
Story Arc: Interestingly, the anime identifies its episodes as belong to these as well as each episode being part X of an arc. They are: The Fall of Shiganshina, The 104th Trainees Squad, The Battle of Trost, Night Before The Counteroffensive, 57th Expedition Beyond the Walls, and The Raid on Stohess District. Fans commonly refer to the last 3 as sub-sections as part of the Female Titan arc.
Strange Salute: With their right hand in a fist over their heart, and their left arm tucked across the small of their back. A Drill Sergeant Nasty explains the fist clenched over their heart symbolizes their commitment to sacrificing their lives for their king. Erwin later invokes this sentiment to ask the recruits if they are willing to give their beating hearts to humanity.
Sunk Cost Fallacy: All of the Titan Shifters are devastated by the things they've done, but refuse to stop doing them with the reasoning that they've "come too far to turn back now."
Special mention goes to DOA, which not only has grammatically perfect lyrics about what it's like to be a member of the Survey Corps, but is also pronounced perfectly as well. This one is because the song is performed by Aimee Blackschleger, an American singer living in Japan who has also contributed music to Guilty Crown and Final Fantasy XIII-2
Survivors Guilt: All over the place, with people losing comrades and/or loved ones left and right. The first ending theme of the anime directly invokes this, as pretty everyone has at one point or another wondered why they survived while their comrades died.
This is part of the deconstruction of Heroic Sacrifice: sacrificing yourself to buy your comrades time to escape and/or give them a clear shot at the Titan holding you is ultimately pointless if they sit there shocked and dumbfounded by the act, likely to become victims themselves. Those that live and are plagued by the guilt become shell-shocked and are less likely to stay effective fighters, making the sacrifice still pointless. The squadmates of Eren very nearly go down this path, in particular the person who witnessed the act, who completely shuts down for a while.
Sympathetic Murder Backstory: After their true identities are revealed, the three Titan Shifters are shown to be seriously messed up because of their crimes. Word of God states Annie is intended to be sympathetic, recalling her Freudian Excuse just before encasing herself in a Crystal Prison, while several chapters and a bonus epilogue are dedicated to showing Reiner and Bertolt to be traumatized and guilty over their crimes. Unlike most examples, however, they continue carrying out their mission.....though it remains unclear exactly why they're doing it in the first place. They claim that they have to do it, with Ymir expressing sympathy for their situation. Everyone else? They fully intend to hunt them down and make them pay.
Not that she wasn't already a badass, but after she and Levi fight the Female Titan, in the Raid on Stohess arc Mikasa is seen employing some of his techniques (notably the spinning, and slashing along muscle planes) to great effect.
Takes One to Kill One: Besides incredibly impractical human weaponry, the only thing that can easily damage a Titan is another one. Includes itself, since Titans often commit self-injury.
Talking Is a Free Action: In Episode 19, Levi gives one of his calm, rational speeches that goes on for paragraph after paragraph seemingly in the space of a dozen hoofbeats as the 104th races through the forest.
When Titan Eren's straddled the Female Titan to keep her down, he internally monologues for several minutes, while she apparently has no choice but to lie there and wait for him to finish. She might have been waiting for her eye to heal, but you'd think she'd still attempt to kick him off somehow.
Later, during their second fight, they both assume fighting stances and Eren similarily has another internal monologue that goes on for a while as they just stand and stare at each other. Of course, the monologues in both these instances may have lasted only a few seconds in real-time, and the scenes were simply slowed down for the viewer's sake and comprehension.
A priest preaches that the Walls will remain impregnable as long as clergy's faith is held fast. They form a human wall, linking arms, and praying in a circle. A Titan promptly smashes through the walls of the church, crushing the people inside.
In the first episode, Eren calls the Garrison soldiers cattle due to how lazy and unconcerned they seem to be, including some who are drunk on duty. One of them mentions that if they're seen fighting, then things have really gone downhill fast. Which is exactly what happens when the Titans breach the Wall...
And most egregiously, before the Titan invasion: the heroes are discussing the Titans, and Armin says that even though the Walls have stood for a century, they could still be broken today. After about 10 seconds of silence, a colossal Titan appears out of nowhere and busts a hole in the Wall.
In Episode 4, after Eren looks at a lot of things humans have done in the last five years since the Titans entered the territory behind Wall Maria. He notes that they're ready for another Titan attack. Guess what happens next?
They Look Just Like Everyone Else: The Titan Shifters are a major source of paranoia for the military, once people realize such a person could exist. How many of them there are, or what their true goals might be, are among the many mysteries of the series. But they are completely undetectable, unless they do something that blows their cover.
Those Two Guys: Reiner and Bertolt. Jean and Marco, especially in the anime, prior to Marco becoming the Dead Sidekick. Krista and Ymir. All manage to subvert the trope, by being much more important as the story goes on.
Thousand-Yard Stare: As one might expect from a series as dark as this. Sporting one is basically short-hand for "I survived a Titan encounter", to the point that in-universe the Drill Sergeant Nasty skips over the recruits who already have one, as they don't need to be broken further. Many experienced soldiers also have one whenever something particularly traumatic happens, like losing a good friend.
Throwing Your Sword Always Works: In one of Levi's fights, he chucks his blades into the eyes of a Titan before slashing out its nape. Justified, in that every soldier carries multiple blades because they wear out quickly. Levi probably just weaponized blades that would otherwise just be thrown away.
Title Drop: As grammatically close as one can get, anyway. During the speech that Dot Pixis made before the attempt to re-take the Trost District, he says, "When this plan succeeds, it'll be the first time we've reconquered land from the Titans! It will mean mankind has finally managed an attack on the Titans!"
To Serve Man: The Titans think humans are very tasty. Evidence suggests that they don't even need to eat in order to survive, nor do they prey on any other animals besides humans.
Tragic Villain: The three Titan infiltrators: Annie Leonhart, Reiner Braun, and Bertolt Hoover. They were sent on their mission at a young age and have began to show varyinglevels of trauma as a result of what they've done. All three express that they just want to go home, and are rapidly driven into a corner with no choice but to complete their mission or die trying. Reiner claims they didn't fully understand things when they started their mission, while Bertolt expresses remorse over their crimes while claiming they haveno choice but to do it.
Implied between Krista, Reiner, and Ymir, with Reiner (though we don't know if he really has a crush on Krista or is just messing with Ymir) and Ymir both looking at Krista, but Krista herself never giving any confirmation on any possible romantic feelings. Reiner only has feelings for Krista when he is experiencing dissociative episodes, which arise as a result of his attachment towards his former teammates and his deep immersion into the role of a soldier. A part of him does like Krista, but it is the part that interferes in his fight to destroy humanity.
The slightly melancholy chorus of the Insert Song 'The Reluctant Heroes' returns as a stirring Leitmotif in several other pieces on the soundtrack, including 'Ri-body-ki-motion' and 'counter*attack-mankind'.
The slightly sad and calm melody of 'eye-water' comes back as a victorious (but equally melancholic) theme in 'Call Your Name' a few times during the anime.
Troubling Unchildlike Behaviour: Eren. He took it upon himself to save Mikasa, planning out how to kill the criminals that had abducted her. His explanation to his father: "I merely put down some rabid dogs. Sometimes they just happen to look like people."
Tyke Bomb: Annie, Reiner, and Bertolt were all still children when they began their mission to exterminate mankind. Annie is shown to have been in training since an early age, though it's unknown how early Reiner and Bertolt began to prepare for their mission.
Laser Guided Tyke Bomb: Eren becomes one for the military, and his memories of being injected with something by his father suggest he had a hand in Eren developing his powers.
Eren, a heroic Titan Shifter looks less human than a normal Titan thanks to its skull-like face, making it a little less creepy. Reiner, a Titan Shifter who became sympathetic to his comrades in the Trainee Corps despite his mission also looks less human. Annie and Bertolt, who hate humans and are more loyal to their mission respectively, are smack dab in the Valley.
Unfriendly Fire: Jean briefly discusses this in Episode 18, when they're ordered to stand guard in the forest of giant trees, mentioning that an unpopular commander may find themselves getting attacked from behind by one of their troops. Armin wonders if he's really going to do that, but Jean tells him he was just thinking out loud and will follow the orders.
The Unreveal: The identity of the "true enemy". Later, Ymir almost reveals a possible answer before being stopped, and refuses to answer when asked a second time.
Unskilled, but Strong: Almost all Titans. They have very little intelligence but can do a lot of damage because of their gigantic size.
Unspoken Plan Guarantee: Erwin invokes this by keeping everyone but a handful of trusted individuals in the dark about his real plan to capture the Female Titan because he suspects (rightly) that an infiltrator would alert the Female Titan to the plan. Subverted in that she manages to break free and escape anyway. Fortunately, the protagonists are still able to identify the Female Titan, thanks to Armin's encounter with her.
Unstoppable Rage: Eren snaps when the Female Titan kills all the people protecting him, and transforms to kill her.
Mikasa when she thinks that Eren has died at the hands of a Titan. During the Battle of Trost, she flies into a Roaring Rampageof Revenge and cuts down several Titans before running out of gas.
Villains Blend in Better: While Sasha is shown to have difficulty adjusting to life outside her isolated village, none of the Titan Shifters from outside the Walls seem to have had any issue passing themselves off as refugees from Wall Maria. Considering that the society within the Walls was supposed to have been isolated for a century, it gives an early nod to the Ancient Conspiracy at play within the upper ranks of society.
Villain Episode: Multiple chapters, as well as one episode of the anime adaptation, could be considered this through their relatively sympathetic focus on the villains. Episode 23 and its counterpart, Chapter 31, focus primarily on Annie prior to The Reveal that she is the Female Titan. Later on in the manga, Chapters 46 through 48 primarily focus on Reiner and Bertolt and provide significant Character Development for them.
Villainous Friendship: Reiner and Bertolt are very close and protective of each other. They, especially Bertolt, also get mad when Armin bluffs about Annie being tortured, though Annie's feelings for them are unknown.
Walking Spoiler: All of the Titan Shifters tend to qualify for this. Annie, Reiner and Bertolt are almost never mentioned without a spoiler tag referencing their status as the moles. Ymir isn't quite as bad. Eren supposedly dies early on in the series, so almost any indication of him surviving being eaten by a Titan, in addition to his shifting ability, is basically spoiler material.
Wall Around the World: Humanity's last settlement is three concentric walls, built to keep out the Titans.
Wardrobe Flaw Of Characterization: Mikasa constantly wears a red scarf that doesn't quite go with her uniform, because Eren gave it to her to keep her warm on the night that she lost her parents.
Warfare Regression: The military is primarily trained in double swords and hand-to-hand combat because flintlock rifles are much less useful personnel weapons for fighting Titans, though cannons still get used in Titan defense and rifles are kept around to enforce the law and to deal with possible civil wars or uprisings.
Was It All a Lie?: Eren wonders this after Annie is revealed to be the Female Titan, and later when Reiner and Bertolt are also revealed to be Titans. Connie states he won't be satisfied until he can ask them face to face. When he does get to ask them, Bertolt breaks down and states that not everything was a lie - he really did consider them comrades, despite his mission, and Eren even wonders if Reiner and Bertolt cracked and developed split personalities from having to both carry out their mission and see the results of it up close.
Was Once a Man: The Titans. When the destruction of Connie's village reveals this, the officers of the Survey Corps are understandably horrified at the implications.
Watching Troy Burn: In Episode 2, as Eren, Armin, and Mikasa, along with many other refugees attempt to flee Zhiganshina, they see smoke and fires rising in the distance, along with cries of terror as the Titans enter the human territory for the first time in a hundred years. Bonus points for their hometown actually being surrounded by walls previously thought to be impregnable.
Weak, but Skilled: The only way the inherently much physically weaker humans can survive multiple Titans encounters is to be very skilled.
We Hardly Knew Ye: Marco Bodt, the first member of the top ten of the 104th Trainee Corps to die, does so off-screen and with hardly any Character Development. The horrific anonymity of his death serves as one of the triggers for Jean's Character Development. Of course, it's heavily implied that the reason he died somewhere where no one was there to see was because Annie killed him. Nifa as well.
Eren and Armin's squadmates Thomas Wagner and Mina Carolina are the first named soldiers to die in the Battle of Trost, and both did so with little screentime. Their other two squadmates Nac Tius and Mylius Zeramuski also die with even less screentime; their names weren't even known before Armin recalled them later.
We Have Become Complacent: Most of humanity got comfortable with 100 years of peace and were completely unprepared for the first Titan attack. Eren even chewed out Hannes and the other Garrison troops for drinking on duty since they didn't think that the Titans would actually breach the wall. After they learn their lesson, the Garrison is at least somewhat more capable by the time of the second attack. The Survey Corps never got lazy during the long lull though the Military Police Brigade was never particularly concerned by the Titans.
Deconstructed with the Survey Corps who regularly suffer countless deaths every mission. Eventually, the Corps faces a serious problem of personnel shortage, as most of their veterans having been killed off in a short time frame and graduating Trainees aren't exactly rushing to sign up for a Red Shirt Army.
Chapter 9 (Episode 8): Eren is alive with all his limbs intact, and was the Titan that attacked the other Titans.
Chapter 31 (Episode 23): The Female Titan is Annie.
Chapter 33 (Episode 25): There are Titans within the Walls.
Chapter 40: Ymir is a Titan as well — and, years ago, killed a childhood friend of two of her comrades.
Chapter 42: Reiner and Bertolt are the Armored Titan and Colossal Titan, respectively.
Chapter 50: Eren is indeed the Coordinate, and it grants him the power to control Titans.
Chapter 51: Titans were once human, and are innocent victims transformed into monsters by some unknown force.
Chapter 53: Pastor Nick is found murdered, and the Survey Corp's investigation of this reveals that there's a Government Conspiracy responsible for both the Wall Titans and the murders of Krista's family.
Chapter 54: Erwin is preparing to stage a military coup d'état.
Chapter 55: Because the Reiss Family is the royal family, Historia will be placed as the new queen by the coup forces.
Chapter 56: There's a group within the Walls actively suppressing humans, and apparently work for the king. Levi's full name is Levi Ackerman and there's a captain in the human-supression task force who called Levi his "pride," and also has a last name of Ackerman.
Chapter 57: Three revelations in a row: That Titans may be able to consume other Titans and obtain their abilities (including Titan-shifting) like Kirby, that Eren could be eaten by one of the Millitary Police's Titan Shifters/captive Titans and inherit his ability to control Titans, and that Ackerman Senior just killed three members of Levi's squad- WAIT, WHAT?
Chapter 58: Jean is seemingly gunned down by Kaney's henchwoman.
Wham Line: The identities of the Armored Titan and Colossal Titan are given freely and unprompted to The Hero by the villains themselves. In a background conversation.
In the OVA episode, during the Apocalyptic Log, it's mentioned that the Titan speaks, says "Ymir-sama", then bows.
"Do you know a man by the name of Levi Ackerman?"
What the Hell, Hero?: In Episode 2, Eren insults Armin for wanting to stay away from the danger while relying on meager handouts. He then throws the bread his friend's grandfather gave them, prompting Mikasa to punch him in the face. She tells him someone so weak who couldn't even have left the city on their own two feet, nor gotten the food without help, would be unable to even stand up to one Titan. She then force feeds him the bread, telling him to survive for now.
During the attempt to capture Annie once she's outed as a traitor, Jean and Mikasa chew out an injured Eren for refusing to fight her due to his feelings for her, bringing up all the people who have put their lives in his hands, including the ones that actually died for him.
Where The Hell Is Springfield?: Due to mention of a Far East and factoids like Chapter 1's title implying a future setting, the world's geography is assumed to be the same. It doesn't help that the Walls is officially have a combined radius of 480 km (almost 600 miles across) or larger then most European countries or American states. This is all only assumption though, as the world outside the Walls is never unknown.
Wide-Eyed Idealist: By comparison, every military recruit that hasn't been mentally broken by encountering a Titan yet and expects good things after training. Some examples stand out, especially Eren, Marco, and Marlo, who are prime examples of soldiers wanting to enter the Survey Corps (Eren) and Military Police Brigade (Marco and Marlo) for the right reasons. Everyone gets a quick dose of the reality that battle with Titans is, though.
Some civilians can be like this, too. Eren sees a young brother and sister admiring the Survey Corps and thinking how awesome they are, just like he did only 5 years ago with his own sister. He can only look away and try not to cry the same way Erwin looked away in shame last time.
World of Badass: Averted. Despite several people in the series being highly proficient at fighting, the vast majority of humans are just regular people that enlist in the military hoping to never actually have to fight, which explains the high casualty rate of every expedition.
Grappler In All Of Us: Eren in Rogue Titan form utilizes this a lot in his second fight against Annie, who is the Female Titan, breaking out an assortment of moves ranging from the triangle choke, armbars, and knee bars.
Considering that, according to Word of God, his Titan formwas based on MMA fighter Yushin Okami, this makes sense.
Xanatos Gambit: No matter what happens, Erwin wins during the 57th expedition beyond the Wall. If they succeed in capturing the Female Titan and prying out its human, the Survey Corps shuts down one of its biggest threats and learns a lot, including about any spies in their ranks. Major victory. If they fail or it manages to escape, because he was using Feed the Mole, he can still identify the infiltrator(s) helping the Female Titan (and by extension the Female Titan itself) based on its belief of Eren's location. Smaller victory.
Also Erwin's plan to capture the Female Titan the second time. If Annie doesn't help, Eren escapes with 3D-manuever gear while Jean distracts the military. If Annie does help, they lead her to the tunnel. If Annie isn't the Female Titan, they use the tunnel to smuggle Eren outside the city and delay his execution until they can find evidence for his trial. If Annie is the Female Titan, people restrain her to stop her from transforming. If she transforms, Eren and the military try to fight and capture her. If she loses, she is captured and used as a reason to keep Eren alive. If she escapes, they exposed a spy and use that to keep Eren alive.
You Killed My Mother: In Chapter 46, Eren confronts Bertolt with this, reminding him of the time he mentioned that a piece of the gate the Colossal Titan kicked landed on his house, breaking his mother's leg so she couldn't escape. Bertolt says that he felt sorry for him back then. Eren... doesn't react well to this and vows to make his death as painful as possible. It is unclear whether Eren believes he is being mocked, is angry that Bertolt felt pity and not guilt, incapable of believingthat someone who has caused so much destruction and death can have "human" emotions like that... or that he doesn't want to believe it, as not doing so makes Bertolt easier to hate and kill.
You Can't Go Home Again: A major theme, with several characters losing their homes and/or families and realizing that they can never return to their former lives. The refugees from Wall Maria, in particular, have lost everything and are forced to struggle to build new lives in Wall Rose.
You Monster!: Eren spends a good portion of Chapter 43 monologuing about how much he hates Reiner and Bertolt for having ruined his life but still having the gall to infiltrate the soldiers and act righteous.
Bertolt to Armin in Chapter 49, when the latter lies and claims with a creepy smile that they've been torturing Annie.
You Shall Not Pass: Mikasa decisively shows how much of a Badass the other humans consider her in-universe by invoking this when the military surrounds her, Armin, and Eren right after his first Titan-shift. No one dares to advance on them with swords because she's stated to be worth one hundred regular soldiers.
Zerg Rush: A large horde of Titans rush to the Female Titan and eat their target before they can be stopped.
Also how the Rogue Titan falls after its rampage in Trost (but not before murdering all the titans in said rush) and how Erwin tries to deal with the Armoured and Colossal Titan kidnapping Eren.
Pretty much the only tactic that normal Titans have, which is also what makes Abnormals and the Shifters so dangerous.
Thanks to his new found power as the coordinate Eren is able to use normal titans in this way, siccing huge horde on Reiner and Bertolt