The order of the titles in the trilogy represent a Spectrum of Stability/Fortitude, or however you would say it. It starts with Unbreakable, being... well, unbreakable. Split, the second movie in the series, suggests that the split parts could still be fairly strong on their own, but suggests a breaking point, that has been reached. Finishing off with Glass, which is very fragile and prone to easily breaking. Unbreakable lampshades the significance of Unbreakable VS Glass in-universe, but the order of the titles just adds to the concept.
Also, the trilogy titles describes each of the main 'powered' people - 'Unbreakable' for the Overseer, 'Split' for the Horde, and now 'Glass' for Mr. Glass. 'Glass' becomes even more appropriate now that all three are in a facility, behind glass, to be examined, to go under the magnifying glass.
Elijah had shades of an Anti-Villain in Unbreakable, killing hundreds of people in order to find and mentor David, the world's first true superhero. If his reason for playing the villain was to bring about a greater good, then why, almost twenty years later, is he happy to work with the murderous Horde and help try to kill the Overseer? Because David was meant to be the first superhero, not the only superhero. Elijah envisioned the Overseer being a public figure, inspiring more superheroes and transforming the world into a Standard Superhero Setting, but the Overseer went The Cowl route instead and after almost twenty years, nothing has changed. So, how does "Mister Glass" force superheroes into the light? By forcing a powerful supervillain into the light first, leaving the Overseer no choice but to expose himself to the public in order to stop the Horde.
Or, he is truly anti-villain, as he found the Clover Group, who are apparently far worse than him by either imprisoning, lobotomizing or flat out killing anyone with superhuman abilities (as we've seen with what they do to the Horde and the Overseer in the end). And he knew the only way to expose them would more than likely result in all three of their deaths, and knew that he needed to get the Horde to be involved because he knew it would be the only way to get the Overseer on camera to be broadcast to the world. The Overseer wouldn't have agreed to it, as he's already spent 19 years keeping in the shadows, and Mister Glass knew that the Horde was the only way to get him to come out and to show everyone both of their abilities. It was for a greater good, because now other supers know they're not alone and the Clover Group cannot be able to cover up superhumans anymore due to the possible large amounts of superhumans who come forward at the end of the film. This was what he meant by "This was an origin story.": it's the origin of the superhero universe as supers are discovering their powers and each other and that they're not alone, all at the price of three lives (Mister Glass, the Overseer and the Beast).
Dr. Staple noticeably calls Mister Glass, the Horde, and the Overseer "superheroes" even though out of the three of them the Overseer is the only one who is heroic. Why does she do this? Because, as a member of the secret society, she doesn't think that there's any appreciable difference.
Who is the ultimate foe of the unbreakable hero? A villain who believes that only "broken" people are pure and worthy of survival.
The tattoo members of the Ancient Conspiracy all have? A three leaf clover. Common, easy to find. A symbol of their dedication to ordinary people, with the rarity of superhumans making them more akin to a four leaf clover.
The question is raised about why the Ancient Conspiracy only recently went after the Overseer, but the Overseer is a Reluctant Hero and if Mister Glass is correct, he was only using a fraction of his true potential when stopping street criminals. Dr. Staple even states that she would have preferred not having to get involved with the Overseer, and presumably if not for his confrontation with the Beast, he would have stayed nothing more than an urban legend and not encouraged the emergence of other superhumans. Because of the Overseer pursuing the Horde though, the Conspiracy's hand was (in their eyes) "forced" to intervene before their battles would draw out more and more superhumans.
A great deal of foreshadowing goes into the buildup and ultimate reveal about the Ancient Conspiracy. At time the question is raised as to why only three superhumans exist, even though Dr. Staple herself states that she has treated (and either "cured" or killed) many like the Overseer, the Horde, and Mister Glass before. Dr. Staple also apparently does not believe in the existence of superhumans and tries to disprove Mister Glass' comic book universe theory, but she, like the other major characters, is strongly associated with a single colour, hinting that there is more to her than she appears.
Dr. Staple has a Meaningful Name on a few levels. She is literally the one thing keeping three superhumans together the way a staple keeps a group of papers together but a "staple" is also something common, as in a staple food, a type of food that's so common as to be dominant in its culture.
In one of the first scenes of Dr. Staple being alone, she puts on her grey overcoat with a dramatic flourish that is evocative of a superhero or supervillain's cape. It's another subtle bit of foreshadowing that she's a supervillain.
Mr. Glass put together a genius plan, but it was Casey, Joseph and Mrs. Price who actually saw it through and used it to ruin the Ancient Conspiracy that killed the Horde, the Overseer, and Mister Glass. It wasn't just the superhumans who made the Clover conspiracy fail, it was the normal people who they claimed to be working for.
Had the Clover Group not intervened when they did, the Horde would have escaped and the Overseer would have recovered, with Mister Glass dying as he did anyways. This is a classic comic book scenario played out time and again: the hero and the villain having an inconclusive battle against each other, and with personal animosity cemented between them by the death of the hero's mentor. In a comic book setting, there would be more battles in the future... but that's when the Ancient Conspiracy acted to end the story... only for Mister Glass to turn it into an Origin Story for the whole superhero universe that they were trying to stop all along.
On a first viewing, it might seem like Dr. Staple's endless monologuing about how each room at the asylum is designed to contain the super-people is just typical Shyamalan over-expositing. On a second viewing, however, it becomes clear that she's actually engaging in a classic villain monologue. After all, she has the heroes and villains trapped; it only makes sense that she would gloat about it too, even at the risk of giving away the truth (that she knows they are superpowered and therefore need elaborate superhuman containment).
There's a lot of headscratching about the superheroes will always give rise to supervillains, because Mister Glass doesn't fit the Clover Group's professed pattern, but he does: he's not the supervillain that was given rise by the Overseer. That was the Beast. The Clover Group created Mr. Glass as their own super-*hero* instead. It took a lot longer than their time frame expected, and he is quite a dark, almost supervillain kind of hero, but Mister Glass wouldn't have had to engage in all those acts of terrorism looking for someone else like him if the Clover Group hadn't been erasing them for all of history.
For all their manipulation and stamping out of comic book tropes, the Clover Group embodies a superhuman-verse trope themselves - groups of supposedly "normal" people prejudiced against those with powers who try to control them, or exterminate them, or force them to hide from the world. Despite all their efforts to ignore it, their world was always a comic-book world.
In Unbreakable, Mister Glass comes to realize David must have a "kryptonite" of his own after he stumbles upon a comic in a comic book shop. That (fictional) comic is called "Sentryman Vs The Coalition of Evil" and he later described to David how The Coalition of Evil is a shadowy evil group trying to discover the weakness of all the superheroes and so they can use those weaknesses to defeat them. This effectively foreshadows the entire Clover Group reveal and their plan in Glass.
In Elijah's Comic Book art gallery at the end of that same movie: David looks at a framed sketch of a villain with Elijah's mother and says that the villain doesn't look very threatening. Her response? "That's what I said to my son. He said, there's always two kinds. The soldier villain who fights the hero with his hands, and then there's the real threat. The brilliant and evil archenemy who fights the hero with his mind." That is exactly what we get in Glass.
What Doctor Staple is trying to do to the main three characters (i.e tear them down psychologically) is all the more fitting once you remember "breaking" a patient is a slang for a psychiatrist/psychologist getting through their mental defenses.
Why would a video of people doing things like lifting a car or bending bars cause any sort of stir when it could just be called a hoax? Because of what the cameras caught afterward: the Philadelphia Police Department drowning an old man who wasn't fighting back, shooting another man even though an innocent girl was in the way, and not even trying to save the life of a black man. Either the police have to admit that they're randomly killing innocents or that those people were somehow dangerous. And if there weren't actually any police there, and just conspiracy members, an entirely different kind of problem opens up.
Earlier in the film, Dr. Staple nearly convinced the Overseer and the Horde that they didn't have powers such as pointing out there being videos of (ordinary) men and women performing incredible psychical feats. The key word is "physical". If the Overseer or the Beast had more fantastic abilities such as flight or throwing fire then yes: people watching would have cried CGI. Instead they only ever display displayed super-strength, a less cinematic superpower, and other abilities that are easier to swallow.
This is all assuming that Mister Glass' only plan was for the general public to believe the video evidence. The mastermind always has a second, deeper plan at work as shown in a split second on the news report showing the video which mentions a mass breakout at Ravenhill of patients who are displaying "superhuman abilities". The point of the video is to tell the world superhumans exist. It's that sane fight that also lets those with superpowers (who have already been treated by Doctor Staple) realize they have been lied to, by others and then themselves, and that yes you are special and you are not alone anymore.
The whole movie can be seen as "Epic of Gilgamesh" retold or repeated in the modern age, with the Overseer playing the role of Gilgamesh and The Beast playing the role of Enkidu. Even the hero name "The Overseer" tells of what the job of the king mostly is, the king oversees things and metes out justice. In ancient times, the Overseer might have become the King, Conan the Barbarian style, on his natural abilities alone if it were the world of might makes right and it would be one of his duties to bring justice to people and punish wrong doers, possibly by beating them up. In modern times, there are fewer Kings and society does not look kindly to people enforcing their own justice. On the other side of the coin, Enkidu is described as half man half beast which was terrorizing the countryside and was made to come to his humanity and to the light of civilization by a woman, a priestess of Ishtar (Patricia "brings Beast to the light" in the movie. Her name is spoken like Pa-trisha and in the real world often shortened like Trish or Trisha, the latter of which is anagram of Ishtar.) He is sent to the city of Ur, fights Gilgamesh and they destroy a lot of the city in their battle. Once they realize nobody is a clear winner or stronger than other, they team up and have many adventures together. In fact, that Epic, one of the oldest in the world, might have been how ancient conspiracy in that world started! With common people getting sick of people with supernatural abilities ruining their day and deciding to stop them. The point of the Epic, the ultimate conclusion, is that everybody is mortal, even the mighty creatures such as Gilgamesh and Enkidu. Thus, the conspiracy has learned their lesson well: you see two "supers" fighting, you stop them before they settle their differences and start adventuring together!
The history of the Ancient Conspiracy reaching back thousands of years givens another meaning to Dr. Staple's line about superhumans being "gods amongst men." Anyone with a passing familiarity to the original myths that the gods weren't what you call "model citizens." Like Mister Glass' theories about the truth about comics, the old myths could have been stories of those with superpowers who were less than responsible with their abilities. Leading to the necessity of Cape Busters to protect ordinary people. They just take too far with eliminating anyone with superpowers.
If we push it even further, almost all ancient myths and legends (especially those from Ancient Greece) end up with a hero dying or being punished for his hubris, often by the gods themselves. It makes sense that "a hero" dies ignoble death if you consider all those myths were changed by the conspiracy to their current form. What will happen to the one who was once a hero, became a king and then he suddenly decides to climb to Olympus and see the gods? He will fall down from his flying horse and die in the gutter. And a dozen more examples. Those myths are meant to be a lesson and warning for superhumans: You are not a god. Try to take that mantle, try to boss people around,try to climb too high, become too big for your sandals and you are going down!
In the theatrical poster displayed on the main page, Dennis is curiously absent despite being a member of the Horde. Then he's banned from the Light after showing his unwillingness to blow up Osaka Tower, revoking his Horde status.
Why do we not see the homeless/disabled people who witness the Beast emerging getting killed, when Split pulled no punches in showing people being eaten alive or crushed to death? Because they weren't killed - if homeless/disabled people were turning up dead seemingly eaten alive, that would have been mentioned at least one on the police radio, so Joseph Dunn would have heard it on the police scanners he has, and that would have given the Overseer something to investigate. Instead, the Beast says that 'he is like them' and it cuts away - they were spared because their experiences of homelessness and the disability of the wheelchair person makes them pure in his eyes.
With Patricia raising the number of The Horde members who believe in The Beast's cause from three out of twenty-four to twelve out of twenty-four, The Horde is more evenly 'split' than ever.
From a YouTube comment
One of Mister Glass' final lines is about how this isn't the climax/showdown, it's actually the origin story.
This isn't the main character dying in a pathetic way, this is the main character's mum and dad being shot in a dirty alleyway. Mister Glass, the Horde, and the Overseer are the martyrs that inspire and drive an upcoming world of heroes and villains. This is the origin of supers, and new heroes seeing the Clover Society drown one of their own in a puddle will put them on guard and position them in opposition to that shady group.
That's the Shayamalan twist. You thought this was a full superhero arc. But it didn't end like one because it was actually the opening incident before the story really begins. Normally 3 full movies aren't devoted to such a small part of a story. This microscope view of things is what made this story different.
Dennis complaining about the pants being ruined when Kevin has been shot is a classic example of skewed priorities. But consider that Dennis was the one who transitioned to the Beast for the first time. Meaning the shirtless Beast running around on all fours and getting blood everywhere is wearing his pants. Dennis must expect his pants to be ruined everytime he takes the light after the Beast.
The Overseer never touches Dr. Staple and she deliberately never let it happen. At least not until before he's killed.
