GLaDOS has quickly become one of the most iconic characters of video games; there's a good reason for this. The character of GLaDOS, while seemingly fairly limited in scope, actually encompases several distinct, humanistic themes, seen throughout history.
Unreliable Narrator[]
Though it is hard to be less reliable than Leonard Shelby.
The Unrealiable Narrator is a subset of several narrator types. It's very often seen in horror, in stories with First Person Point of View, thrillers/mysteries, and most things that attempt to analyse humanity from the inside out. "Unreliable Narrator," has only existed as a term since 1961, coined by Wayne Booth. However, the concept itself has been around for much longer. For instance, Geoffery Chaucer's Canterbury Tales, written almost 1000 years ago, features several unreliable narrators.
This isn't something that's surprising. The unreliable narrator is such a longstanding theme in literature because it's a longstanding theme in humanity. We, as humans, constantly forget facts, struggle to see things from different perspectives, or misunderstand situations. In some ways this becomes even more prevalent as we become a text-based culture, where we lose several levels of meaning, including those from body language or intonation. We are obsessed with how completely unreliable we, and the people around us are -- and, unless we become 100% rationally thinking machines, we always will be. Perhaps this is why GLaDOS is such a fascinating character to us: she is a machine, yet she becomes human, almost completely through how untrustworthy she is.
GLaDOS is one of the epitomes of an unreliable narrator. In fact, it's to the extent that it even becomes a game mechanic (more about it here ). In a narrative perspective, though, GLaDOS' primary purpose is to quite literally narrate, or tell the game to you. It's just that, well, she tends to tell the game to you incorrectly. Consider the Cake. Chell not getting the cake -- "The Cake is a Lie" -- is one level of deception. But there are actually two ways that GLaDOS is unreliable here. First, she tells you that you will receive cake when you don't. She then tells you "all the cake is gone!" But this isn't true either! In fact, she was telling the truth the first time, when she said, "Cake...will be available at the conclusion of the test." It’s just not available to you. And this is the key to GLaDOS as an unreliable narrator: making her so unreliable that not only do you not know when she's telling the truth -- you don't believe when she is.
Both of the stories recommended are suspense or horror stories. The Turn of the Screw is primarily a suspense novel. It is presented as a factual representation, but throughout the reader becomes aware of the many sides of the governess, and how little way there is to tell which one is the best portrayal.
The Cask of Amontillado is a short story by Edgar Allan Poe, conveyed through the perspective of a murderer. (Generally, it's a good idea to assume that murderers are unreliable narrators.) The question of the story, though, lies in the motive. Unanswered questions are also indicators of people who are untrustworthy – why, after all, would a murderer so explicit in explaining his crime never explain his motive?
Source: Steve Bowler. http://www.game-ism.com/2008/04/04/still-alive-shes-free/
Bound Women[]
Bound Women is a concept that one only finds sporadically as a major theme throughout history. Until very recently (relative to how long the written word has been a thing), women haven't been that big of a deal in the written word -- and if they were, no one really cared if they were bound or not (notable exceptions can be given to Chaucer and certain Greek plays (though it's up in the air whether the Greek authors were looking to empower or make fun of women)). However, as we move into the 19th century, literature featuring women started popping up, especially as women more and more became literate. To no one's surprised, much of this fiction revolved around the concept of being metaphorically bound to certain standards and ideals; the obvious to point out in this regard is Jane Austen, whose purpose in writing was to show certain social stratifications for women.
GLaDOS, however, cannot be compared quite so well to Austen. GLaDOS is much more of a literally bound woman, as much as a metaphorically bound one. Taking a step further, GLaDOS, in reality, is not a woman, but an object made to seem human. Rather than taking us farther from the bound woman concept, though, this actually takes us closer, in that for much of history, and even today in some cases, women have been traditionally treated as lesser humans than men; closer to objects than human. Traditionally, too, women have been, when showing emotion beyond what is expected, considered "mad," or "hysterical." (Hysterical, of course, being a word derived specifically from "Female Hysteria," an old medical diagnosis for women who, essentially, had emotion or desire outside of a very narrow range. It was treated very often "pelvic message," or, essentially, an orgasm. However, not often being a desired treatment, really we can say that this abundance of emotion was treated with sexual assault.) GLaDOS does suffer an, to quote Gaius Baltar, "Overabundance of emotion." However, GLaDOS' emotion lies in a rather manic, near-psychopathic area. The ironic twist lies in the fact that GLaDOS' hysterical emotion -- and her, as we learn in Portal 2, drive to maintain that hysterical emotion -- is first programmed primarily, if not completely, by men, and then is what propels her into a Godlike state (see: God is Dead (and We Have Killed Him).
It's thus this very dark, objectifying, emotion-driven area of bound women that we can look at when comparing GLaDOS to literature. There are several good stories, novels, and studies that one could read in looking at this, but the two suggested here are The Yellow Wallpaper, a short story by Charlotte Perkins Gilman, and the famous Jane Eyre, by Charlotte Bronte.
Jane Eyre here is used to examine the "madwomen hidden in the attic," concept. While the book does not revolve around the bound woman like other stories may, the ways that Bertha Mason, Mr. Rochester's wife, interacts with the plot throughout the novel is very similar to the way that GLaDOS interferes with the plot of Portal. And, of course, the ways that problems are solved in reference to GLaDOS and they ways that problems are solved in reference to Bertha are shockingly similar.
The Yellow Wallpaper, however, looks more closely at the bound woman concept. "Mad woman," is also somewhat appropriate, but where Bertha is obviously made out to be mad from the outset, The Yellow Wallpaper looks more closely at the madness forced on women, and a connection can be mad with GLaDOS in that aspect. The primary focus, though, can be placed on the similarities between how unaware the two narrators, GLaDOS and the woman in The Yellow Wallpaper, are of their evident "madness," and how they both, in their own ways, ascend the bounds they’re forced into.
God is Dead (and We Have Killed Him)[]
"God is dead. God remains dead. And we have killed him. Yet his shadow still looms. How shall we comfort ourselves, the murderers of all murderers? What was holiest and mightiest of all that the world has yet owned has bled to death under our knives: who will wipe this blood off us? What water is there for us to clean ourselves? What festivals of atonement, what sacred games shall we have to invent? Is not the greatness of this deed too great for us? Must we ourselves not become gods simply to appear worthy of it?"
—Nietzsche, The Gay Science, Section 125
Dying Gods have been a theme in humanity for about as long as Gods have existed. Today we call dead Gods, or Gods no longer believed in, "mythology." We study the dead Gods, but we do not believe in them -- and belief is the only thing that keeps Gods alive, at least as far as humans are concerned.
We need to take a pretty big step back to get at this theme, and start really looking at Portal as a metaphor. In this contained system, GLaDOS becomes god-like. She supposedly killed off Aperture, and now the fate of Chell rests in her hands. Hypothetically, GLaDOS even has the power to kill Chell at any second. The only reason she doesn't, again supposedly, is the morality core she has. In this way, at the end of the game, we as players are literally killing God.
But is GLaDOS really God? And, knowing that she is an unreliable narrator, are all the things we believe actually true? There are answers and arguments to be made on many fronts, but this isn't a section to convince you of anything. I can merely point to Nietzsche's The Gay Science, say that I found my answer in section 344, and challenge you to find one of your own. The Gay Science, where Nietzsche’s famous quote “God is Dead” (seen above) comes from mostly analyses poetry; however it does get into many aspects of science and faith. It takes more than a little thinking to piece things together, but it is well worth the effort.
The other book suggested, American Gods, by Neil Gaiman, is much more straight-forward. The premise of this book lies in a, as far as themes about Gods go, somewhat common theme: Gods, and mythological creatures, literally exist only so long as we, as humans, believe in them. Without belief, these beings cease to exist not just to humans, but in general. Think about GLaDOS, and about Aperture in general. Without human belief in science, would either of these entities exist? If we believed that GLaDOS was righteous in seemingly destroying Aperture, would we kill her? And, finally, can believe in science create Gods from men?