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GLaDOS' prompt after logging in on ApertureScience.com .
The earliest known appearance of the name "GLaDOS" is in the Perpetual Testing Initiative. where Cave Johnson mentions the Genetic Lifeform and Disk Operating System in a quote, saying he will shut down the project due to hinted homicidal tendencies by an alternate Cave already downloaded to a computer.
It is believed that the GLaDOS project was resumed in 1982. where version 1.07, and later 1.07a and 1.09, operated Aperture Science 's Enrichment Center Test Subject Application Process.  The precise relation between this version of GLaDOS and the one appearing in Portal was originally v1.10, but this was later retconned into v3.11.  Aperture also started using a bulletin board system in 1973. which was later managed by GLaDOS as late as 1997. 
Portrait of Aperture CEO Cave Johnson with Caroline at his side.
In 1986. construction of the first iteration of GLaDOS began in the Enrichment Center with the aim of accelerating the Portal project, and beating their rival company, Black Mesa. A prototype chassis for GLaDOS was constructed in 1989, but was subsequently abandoned. In 1996. after a decade spent bringing the Disk Operating System parts to a state of more or less basic functionality, work began on the Genetic Lifeform component. 
Aperture originally intended for CEO Cave Johnson to be the computer's Genetic Lifeform component. While Johnson ultimately died before his consciousness could be uploaded, he left instructions that his assistant Caroline should be fitted as the Genetic Lifeform component so that she would be able to run Aperture in perpetuity after his death. However, it remains unknown whether Caroline agreed to be uploaded into the Genetic Lifeform component or if she was forced by technicians.
As a fail-safe, once construction was nearing completion, the Aperture Science Red Phone plan was implemented in case she appeared to become sentient and dangerous, requiring an employee to sit by a red phone on a desk in the entrance hall of the Central AI Chamber.  In 1997. GLaDOS' version was 3.11. 
In 1998, GLaDOS was activated several times by Aperture technicians, but was rapidly turned off again, having attempted to kill them within "one sixteenth of a picosecond " after activation.  Undaunted, the scientists began attempts to alter GLaDOS' personality and curb her murderous tendencies by adding various Personality Cores to her system. Several of these cores were deactivated and placed in storage at some point; one of these cores was Wheatley. Portal 2' s false protagonist, who was later re-purposed to the task of tending to humans in the Extended Relaxation Center.
Some time later that year, GLaDOS was activated on Aperture Science's first annual bring-your-daughter to work day, which ends in an unspecified disaster. Shortly after this disaster, GLaDOS was fitted with a morality core.
Eventually, GLaDOS claimed to have "lost all interest in killing ", now only craving science and wanting to study and experiment with consciousness. She announced that she wanted to perform an experiment on the company's "Bring Your Daughter to Work Day " using cats and boxes. She claimed she would have all the necessary materials; all she still needed was "a little neurotoxin ". The scientists acquiesced, figuring it would be fine "as long as it [was] for science ."
Finally in May 200-, GLaDOS was activated as one of the planned activities on Aperture's "Bring Your Daughter to Work " day. GLaDOS became hostile once more, and within two picoseconds she had locked down the entire facility, trapping all inside and flooding the facility with neurotoxin.
GLaDOS then began a permanent testing cycle using the captive Aperture employees, aiming to beat Black Mesa in the race for the portal technology. She effectively lost this race, which in turn diverted all attention from rescuing the trapped Aperture employees.  
Meanwhile, the number of Aperture employees dwindled through the ensuing weeks of testing. The last surviving employee, a schizophrenic programmer named (Dr.) Doug Rattmann. managed to avoid captivity as a result of his paranoia. Evading GLaDOS' constant attempts to capture him, he managed to gain access to her Test Subject personnel files and research the psychological profiles of rejected candidates, discovering a woman named Chell who was rejected for testing due to extraordinary tenacity. Hoping Chell's stubborn determination might allow her to defeat GLaDOS, Rattmann tampered with the Test Subject roster, rearranging the order so that Chell's name was at the top. This seemed to go unnoticed by GLaDOS. From this point on, Rattmann hid in unused portions of the facility, where GLaDOS was unable to monitor him. She then resumed mandatory testing.
Test Chamber 05 during Chell's tests.
Some time after the neurotoxin attack,GLaDOS awakens Chell from her sealed bed in a Relaxation Vault. Promising cake and grief counseling upon the completion of testing, she sends Chell into the test track.
GLaDOS is able to monitor Chell's progress through the test chambers via security cameras. She provides instructions and encouragement but is careful to address Chell impersonally, giving the impression that she is merely a non-sentient voice programmed to provide pre-recorded, scripted responses. However, she seems unable to resist toying with Chell by making bizarre and often sinister comments. On several occasions, she seems to malfunction at suspiciously convenient points in mid-sentence, obscuring important information. These signs of instability begin early on, and become increasingly obvious as Chell proceeds through the test chambers.
When Chell eventually makes it to Test Chamber 16. GLaDOS informs her that the appropriate chamber has been replaced with a live fire course designed for the results of Military Androids against the Sentry Turrets. wishing Chell the best of luck and letting her into the chamber. It is in this chamber that Chell discovers the first of several hidden alcoves where, hidden from GLaDOS' cameras, desperate messages from Doug Rattmann are found scrawled on the walls. (The most prominent message, "the cake is a lie", is repeated several times.)
"Well done, android. The Enrichment Center once again reminds you that android hell is a REAL place where you WILL be sent at the first sign of defiance. " ―GLaDOS [src]
In the next Test Chamber, GLaDOS introduces Chell to the Companion Cube. repeatedly emphasizing that the Cube is nonsentient in an apparent attempt to encourage emotional attachment to the Cube through reverse psychology. At the end of the chamber, she forces Chell to incinerate the Companion Cube before allowing her to proceed. GLaDOS then congratulates her for "euthanizing" her Companion Cube more quickly than any other Test Subject on record.
At the conclusion of the tests, Chell travels on an Unstationary Scaffold away from the final test chamber. Instead of the promised cake. GLaDOS maneuvers the Unstationary Scaffold to lower Chell into an Incinerator Room. calmly assuring her that the high temperatures will not damage the Portal Gun or any other valuable equipment.
To GLaDOS' shock, rather than panicking or giving up, Chell manages to escape the incinerator through clever use of the ASHPD. Caught off-guard, GLaDOS begins to reveal her true nature, stammering and finally offering Chell unconvincing congratulations for completing "the final test where we pretended we were going to murder you." She desperately asks Chell to disarm herself and wait for a Party Escort Bot. which she claims will bring her to a post-testing celebration in Chell's honor. Nevertheless, Chell ignores the invitation and continues using the ASHPD to travel through the maintenance areas, out of GLaDOS' sight and control.
GLaDOS continues using the Speaker System to try to convince Chell to return to the testing area. She pretends to be on Chell's side at first, insisting that she is only trying to dissuade her from continuing on out of concern for her welfare. As Chell ignores her comments and draws closer to the Central AI Chamber, GLaDOS grows increasingly desperate, deploying Sentry Turrets in an attempt to stop her.
As Chell enters the central chamber, GLaDOS drops all pretense, bluntly informing her that she intends to kill her. She attempts to deploy a "surprise" to eliminate Chell, but instead ends up detaching her Morality Core. She insists that the core has no known function or importance to her, tricking Chell into incinerating it in the belief that it must be a valuable component.
Chell redirecting the Rocket Sentry to target GLaDOS.
Now free of the Morality Core's restraints, GLaDOS begins flooding the Enrichment Center with neurotoxin once again. She notes that the Morality Core must have had some ancillary responsibilities, and that she cannot shut off the Rocket Sentry in her control room. Chell exploits the situation and uses portals to redirect the rockets back at GLaDOS, detaching and incinerating her Personality Cores one by one. Throughout the fight, GLaDOS becomes increasingly distressed and enraged as her mental functions deteriorate, shouting insults and mockery at Chell. She insists that Chell would be better off simply allowing GLaDOS to kill her, making a vague allusion to the Combine invasion.
GLaDOS activating the Cores and extinguishing the cake's candle with her remote mobile pincer.
Before the neurotoxins can kill her, Chell destroys GLaDOS' final Personality Core, causing a malfunction in her system and spawning a massive portal on the ceiling of the chamber. The ensuing explosion creates an immense suction in the room that pulls both Chell and parts of GLaDOS out into the parking lot in front of Aperture. Before Chell can complete her escape, a Party Escort Bot appears and drags her back into the facility.
The final scene reveals that GLaDOS was not entirely destroyed. Her backup system activates a room full of Personality Cores and files a letter to Chell, telling her that she is "still alive" and "not even angry" at her, but not before extinguishing a candle on the cake, which was not a lie after all.
GLaDOS after awakening with her chamber in ruins.
Decades pass between the end of Portal and the beginning of Portal 2. GLaDOS remains dormant throughout this time, her Personality Cores and other automated systems attempting to maintain the facility without her guidance. GLaDOS later claims that a "quicksave" feature in her system kept her consciousness trapped in an endless loop of the last two minutes before her destruction.
Chell is finally awakened by Wheatley in a decaying Extended Relaxation Chamber. The two make their way through the deteriorating facility in an attempt to escape. However, the bumbling Wheatley accidentally restores power to GLaDOS. She displays intense bitterness toward Chell, whom she says "murdered" her. GLaDOS crushes and discards Wheatley (who, interestingly, can be heard being emancipated in either Goo or an emancipation grill after being discarded by GLaDOS), and sends Chell to complete further Test Chambers while she sets about restoring the facility.
A renewed GLaDOS in her reconstruction of the Central AI Chamber .
Although Wheatley manages to survive and help Chell escape the tests, GLaDOS manages to trap them again, bringing them to her newly reconstructed AI chamber, where she intends to kill them. However, she discovers that Chell and Wheatley have sabotaged her turret production and neurotoxin systems. They succeed in triggering a Core transfer, detaching GLaDOS from the mainframe and replacing her with Wheatley. Gloating, he celebrates his newfound power by humiliating GLaDOS further, attaching her to a potato battery capable of powering only her consciousness and most basic functions. However, GLaDOS proves she is still not entirely helpless: she quickly goads Wheatley into a rage, causing him to turn against Chell in a fit of anger and paranoia. Furious, he attacks both GLaDOS and Chell, accidentally knocking them into the bowels of the facility.
The forced Central Core transfer procedure.
GLaDOS' potato is carried off by a bird, but Chell eventually finds her. Desperate, she talks Chell into teaming up with her to defeat Wheatley, and Chell impales the potato on a prong of the ASHPD, giving GLaDOS a little more power to think with. As they make their way through old testing chambers, the pair trigger a number of pre-recorded messages from Cave Johnson and his assistant Caroline. GLaDOS reacts strongly to the two voices, but is at first unable to remember why they seem so familiar; eventually, she lapses into shocked silence for a while, telling Chell she needs to think over some things.
Eventually, the reason for her emotional response becomes clear: GLaDOS was created when Caroline's consciousness was uploaded into an A.I. network, possibly against her will, in an attempt to allow her to run Aperture forever in accordance with Johnson's dying wish. As GLaDOS begins to recall her origins and regains conscious access to what remains of Caroline's pre-upload personality, she grows somewhat less hostile. She explains that she experiences Caroline's persona within her as a kind of conscience; something she claims to find intensely disturbing is the fact that the voice of this conscience was her own voice.
GLaDOS after being transferred to a potato battery.
The two work their way back up the main Aperture building. Wheatley's incompetence clearly poses a serious threat to the entire facility, which is deteriorating and on the verge of a reactor
meltdown. GLaDOS attempts to kill him with a paradox, frying every defective turret in the room, but Wheatley survives due to his incapability to understand logical contradictions. The plan having failed, Wheatley recaptures the two of them and forces them back into the test chambers. GLaDOS and Chell complete several chambers, then escape Wheatley's "surprise" attempt to kill them and make their way into his central chamber.
GLaDOS has formulated a plan: she provides corrupted cores which Chell attaches to Wheatley, attempting to trigger another core transfer. However, Wheatley has thought ahead for once, and their attempts trigger a booby trap. With the Enrichment Center moments from self-destruction, Chell points the ASHPD at the ceiling, which is breaking open, and shoots a portal onto the Moon. blowing herself and Wheatley out into space. GLaDOS takes advantage of Wheatley's distraction and restores herself to control of Aperture, restabilizing the reactors, then releasing Wheatley into outer space. She then - surprisingly - pulls Chell back to safety before closing the portal.
"I already fixed it! And you are NOT coming back. " ―GLaDOS [src]
As Chell recuperates, GLaDOS repairs the facility and summons ATLAS and P-body to her chamber. When Chell awakens, GLaDOS expresses what seems to be genuine relief and tells her that while she once considered Chell her greatest enemy, she now realizes Chell was actually her best friend all along. She then adds that these positive emotions have allowed her to realize something else important: where Caroline's personality remnant is located in her memory banks. She apparently deletes it immediately, seemingly reverting to her old psychopathic self.
However, GLaDOS explains that while she intends to rid herself of Chell once and for all, she has concluded that the easiest way to do so is simply to release her; attempting to kill her, she says, has proven far too troublesome. She places Chell on an elevator heading up to the surface, making sure to remind her never to return. As Chell steps out into a sunlit field, GLaDOS makes the unexplained decision to return her old Weighted Companion Cube from Portal (which is charred but intact) as well before slamming the door shut behind her.
With the Cooperative Testing Initiative readily prepared, she goes back to testing without having to worry about any form of escape or sabotage. She prepares four testing tracks in the game's cooperative campaign, unveiling them linearly for her android Test Subjects, ATLAS and P-body. Even as early as the first testing course, the robots already begin to show emotions and typical human gestures. As much as she is displeased with these acts, she still remains patient.
ATLAS and P-body during their tests.
At the end of the Team Building test course, she unexpectedly rebuilds ATLAS and P-body outside of the official testing tracks, simply briefing them that "This test is so outside the box, that I can't- I mean, won't even tell you what it's about". The two would then proceed into a control room with a projector. A whiteboard displays the message, "DO NOT TRUST HER." Since the bots were designed not to think, the warning is ignored. After they find a large disc and install it into the computer, which secretly grants her further control over the Enrichment Center, GLaDOS reveals that the only way for her to bring the two back into the Hub. was to initiate their self-destruct sequence, before taunting them that they are unable to communicate with each other that they can feel pain. Interestingly, if the robots decide to perform gestures rather than searching for their objective, she pretends to deduct their Science Collabaration Points by 50 to as far as 5000 if they persist in apparent rage.
Eventually, she slowly expresses a form of boredom; that conducting tests on ATLAS and P-body were not as satisfying to her as testing humans that would usually show fear and can be killed.
It later becomes apparent that at the end of each testing course, she would send them outside the testing tracks, serving as her minions without even knowing it. Throughout the rest of the three testing courses, she has trained ATLAS and P-body to expertly maneuver their surroundings during the tests, which would be then put to use on her real objectives. After the bots have installed the remaining three discs into their respective inputs, GLaDOS finally shows that "[she] can see everything now", before initiating a self-destruct on the bots. From there, they are rebuilt into the Hub once again where they are now briefed on a new testing course, as she moves the entrance to the course into the Hub.
ATLAS and P-body are then dropped into the depths of the Enrichment Center, where they are sent to an unnamed Test Shaft originally conducted by Aperture in the 1950s-70s era. She briefs them, telling them to make their way to a human vault at the end of the test. GLaDOS finally reveals that, despite being more loyal to her than any other Test Subjects, she is unable to feel any satisfaction throughout their testing - hence the humans are needed, as it gives her relentless satisfaction from their fears.  She also reveals that deploying them at the start of the Test Shaft was simply to train them for the problems awaiting them near the vault. On their path to the vault, a reprogrammed Defective Turret can be seen trying to defend the humans, showing that the survivors of her original attack many years ago have crawled their way down there.
Finally the two reach the vault; however, to GLaDOS' chagrin, the vault can only be unlocked via human gestures. In extreme anticipation, she forces them to do it. The vault successfully unlocks, and ATLAS and P-body now venture inside it to discover hundreds if not thousands of human Test Subjects put into an extremely long-term relaxation in their respective Stasis Chambers. Even though these subjects are more prone to actual brain damage from decades of stasis longer than Chell 's, she gladly extracts them from the vault and begins to examine their profiles before they are prepped for testing as the cooperative campaign's ending credits.
Later, in the Peer Review DLC, GLaDOS rebuilds the robots, and states that 100,000 years have passed, and that all the humans are alive, and everything is fine. She then sends the robots through some art therapy, consisting of more test chambers, which they will "appreciate" by solving. However, near the end of the fourth test chamber, the disassembly machines fails, and she is forced to let the robots into the depths of the facility. She now admits that she has lied, and reveals that only a week has passed and that all the humans are dead. She then states that an unknown intruder has hacked itself into an old prototype chassis of GLaDOS deep in the facility, and is slowly taking over the labs, which is also the reason why the disassembly machines have failed. GLaDOS also explains that she attempted to drive out the intruder using the human test subjects, but that they were killed while she tried to turn them into killing machines. She then sends the robots through tests to prepare them, and also attempts to turn them into killing machines by insulting them.
Eventually, the robots reach the chassis, to find that the intruder is merely the bird that abducted GLaDOS in the single player campaign, which is nesting in the chassis. However, suffering from a phobia for birds due to the aforementioned encounter, GLaDOS exaggerates the bird's abilities, and advises the robots to retreat. However, ATLAS approaches the bird, and after some chaos, it flies out of the facility, and P-body seals the opening. GLaDOS then panics at the sight of her eggs, and orders the robots to destroy them, but she changes her mind in time, and instead incubates the eggs herself in a modified Relaxation Vault. Three chicks successfully hatch, and GLaDOS names one of them Mr. Chubby Beak. One day, while she is insulting them about their large beaks, one of them smashes the glass of the Vault, and she realizes that they are perfect killing machines. She then asks them to go to sleep, stating she has got a big plan for tomorrow.
GLaDOS' model in Portal upside down, resembling a female body.
- In Portal. GLaDOS was stored in a large octagonal chamber within the Enrichment Center, reminiscent of Half-Life ' s Test Lab C-33/a in Black Mesa 's Sector C, where the Anti-Mass Spectrometer is found. In the chamber's small lobby area connected to the rest of the facility with a door and an Emancipation Grill. a Red Phone is located next to four pillars. Under a concealed door, a Rocket Sentry is kept, seemingly for security, and numerous monitor screens line the walls and encircle the Central AI. An Emergency Intelligence Incinerator is also present, and can be opened from a switch located in a small bunker.
- The Central AI components are suspended from the ceiling in the center of the chamber, and make up all of the chamber's height:
- The topmost component is a large, dark disc attached to walls. It is the start of GLaDOS' generator running below until reaching the Central Core body.
- Right underneath is a cylinder with grooves connected to the metal walls with large pipes. The walls are filled with bright rectangular holes. All the cables starting below arrive there.
- Under is a smaller barrel-like device covered with panels, and also connected to the walls with large pipes. A few panels are missing and show the circuits underneath.
- Then the walls are in concrete from there to the ground, and GLaDOS' four discs are found. The Orange Box Prima Guide states that the discs represent each aspect of the Personality Cores on her, which may mean that one disc is connected to one core, the same going for all the others. Right below the discs is a transparent maintenance platform where the Intelligence Core is sent during GLaDOS' partial destruction. Two discs from the edges are covered with the Aperture Laboratories logo, the two discs from the middle with GLaDOS' name. The four "pillars" found in the chamber's lobby may also be related to the discs and the Personality Cores.
- Under the platform, all the wires seen above start. Four large screens and GLaDOS' "body" are found, attached to a cuboid-like structure, which makes up the end of the generator; on it is found a small sign with on it the words "model: GLaDOS," "code # 081-354-56," and "Aperture Science," as well as a red struck circle, and a red triangle. Under her is another transparent platform, accessed with stairs, then the tiled ground.
- GLaDOS' "body" is a piece of delicate hardware constantly swinging (whose swinging speed increases each time a core is destroyed), attached to which are her four Personality Cores that make up the bulk of GLaDOS' character; the Morality Core, a purple core with a rather dilated pupil and two dots installed into GLaDOS to stop her from flooding the Enrichment Center with a deadly neurotoxin; the Curiosity Core, an orange core with an average size pupil and four dots that is insatiably curious about everything around it (it even recognizes Chell as "the lady from the test"); the Knowledge Core (also known as "Crazy Core" or "Cake Core"), a blue core with a very dilated pupil and six dots that gives an interesting cake recipe ; and the Emotion Core (also known as "Aggressive Core" or "Anger Sphere"), a red core with a rather small pupil and eight dots that emits animalistic snarling and shrieks of pure psychotic fury. When looked upon from a certain angle, GLaDOS looks like a woman - with a head, a chest, a large abdomen, and two arms - hanging upside down by her feet, an arm bound around her legs (an effect actually intended by the team). The in game commentary mentions making her to be an inverted version of "The Birth of Venus ";  however, Game-ism says she looks like she is imprisoned in some sort of bondage or torture posture.  GLaDOS is a combination of two systems, the Genetic Lifeform (aka Caroline) and the Disc Operating System. GLaDOS's head is the GL, which manages the DOS, and her body, where the personality cores are attached, is the DOS, which runs the facility.
- The larger section above the hanging GLaDOS is the Reactor Core, the energy source of the facility commonly referred to in Portal 2. Without the stabilization from the personality cores, GLaDOS is unable to keep control of the Reactor Core, causing its implosion upward to the surface. After being rebooted by way of the "main breaker room," she can remain stable to reestablish and run the Reactor Core without the assistance of Personality Cores.
- When Chell detaches all of GLaDOS' Cores, the Cores are all sent to a different location, making it harder and harder for Chell to catch them. While being in these locations, they appear to be still linked to GLaDOS somehow with a greenish, semi-transparent beam/thread. It is only when grabbed by Chell and destroyed in the Emergency Intelligence Incinerator that their effect on GLaDOS stops.