Story

Chell, as seen in Portal

Throughout the Portal series, you take on the role of Chell, a young woman trapped within the Aperture Science facility. Chell is forced to solve tests of varying difficulty in chambers designed by a psychopathic AI named GLaDOS. During the early stages of the testing, Chell is granted usage of the Aperture Science Handheld Portal Device (commonly referred to as the portal gun), a piece of equipment developed by Aperture Science that allows Chell to create portals that act as gates between each other, allowing Chell to quickly traverse areas or reach normally unreachable places.

Portal

Main article: Portal

Portal has two distinct parts, the test chambers, and the escape.

Act 1: The Test Chambers

Main article: Portal 1 Test Chambers

The game begins with Chell awakening in a Relaxation Vault, where she is briefed by the voice of GLaDOS coming from speakers, before being released through a portal. The player is introduced to the testing process and mechanics, shortly thereafter obtaining the Aperture Science Handheld Portal Device. As Chell makes her way through test chambers, it becomes clear the facility is devoid of human life and GLaDOS is testing Chell for her own warped definition of 'science'. Throughout the facility are hidden dens, containing mad scribblings from an unseen person warning others of GLaDOS. Motivated with the promise of cake at the end of the testing, Chell is put through tests of increasing complexity. When Chell is no longer of any use to GLaDOS, she attempts to kill Chell by lowering her into an incinerator. Quickly thinking, Chell escapes a fiery fate using the Handheld Portal Device, and she makes her way through the inner facility via maintenance shafts.

Act 2: The Escape

While Chell is making her way through the facility, GLaDOS attempts to lure her back with promises of cake and a party, and claims the attempted murder of the player was a misunderstanding. When she realizes her attempts are in vain, GLaDOS resorts to taunting Chell while continuing her efforts to kill her. Eventually, Chell reaches GLaDOS' lair, where she finally comes face to face with the rogue AI. It is revealed that GLaDOS had murdered everyone in the facility using deadly neurotoxin. GLaDOS now attempts to do the same to Chell. Using the Portal Device, Chell defeats GLaDOS by removing her personality cores and depositing them in a nearby Emergency Intelligence Incinerator, resulting in a large explosion that blows a hole in the roof dragging both Chell and GLaDOS upwards. Chell awakens to find herself above ground in the parking lot of the facility, with the burning remains of GLaDOS surrounding her. The March 3, 2010 Patch modified the ending so that Chell is dragged back into the facility by the unseen Party Escort Bot, that is connected to the Portal 2: Lab Rat comic.

Portal: Still Alive

Main article: Portal: Still Alive

Portal: Still Alive is an XBOX Live Arcade port of Portal, containing additional content in the form of new advanced chambers, inspired by Portal: The Flash Version, with no additional story material. This version of the game is not canon to the story, as it's confirmed by anonymous Valve developers.

Portal 2: Lab Rat

The Lab Rat comic bridges the gap between Portal and Portal 2, which introduces us to Doug Rattmann, a scientist at Aperture Science who survived the Neurotoxin after GLaDOS' first activation at the Bring Your Daughter to Work Day, which made her self-aware and initiated a lockdown on the facility, and killed most of the scientists with neurotoxin.

Part 1

Part 1 follows Doug Rattmann as he is tracking Chell through the Enrichment Center. He is having a monologue about reality and how the mind sees it and is shown to be psychotic, forced to take ziaprazidone [sic] to curb the effects of his schizophrenia. Through the story, he carries a Companion Cube that he hears talking to him and giving him advice. The main story is also intersected with flashbacks of the period during which GLaDOS was still being built, showing Rattmann's involvement in the project.

Soon after discovering Chell, it appears he has not taken his medication for a while, and he takes his two final pills, against the Companion Cube's advice not to take them. A first flashback is shown, with a younger Rattmann overhearing two colleagues saying they put cameras in the cameras, something that an unidentified person is not to suspect. While he runs through the facility and makes another mural, Chell reaches Test Chamber 19, and finally GLaDOS' chamber, where she destroys her.

Then another flashback set in GLaDOS' chamber is shown. There Rattmann is seen working with his colleague Henry, who compares their breakthrough with GLaDOS to Einstein discovering relativity and NASA reaching the Moon. Rattmann expresses his doubts about GLaDOS' reliability, since she always attempts to kill everyone when being powered.

Back to reality, Rattmann reaches for the surface, where he thinks Chell is. When he finds her, the Party Escort Bot is dragging her back into the facility.

Then a third flashback has Henry showing Rattmann the newly designed Morality Core, which is supposed to dampen GLaDOS' urge to kill.

Again back to reality, the Cube tells Rattmann to run away while he is outside, but feeling he is responsible for the whole mess, he prefers to get back inside, and save her.

Part 2

Part 2 opens with Doug Rattmann traversing the innards of the facility. The Companion Cube informs him that the anti-psychotic he took in Part 1 is starting to work, as the Cube slowly fades to silence. Doug finds Chell in her Cryo-Chamber in the Relaxation Center, where the Party Escort Bot has placed her. He decides to try to save her by getting to Cryo-Control, but the Sentry Turrets block his way. Finding a panel in the wall, he quickly realizes that GLaDOS' destruction blew the main power grid and that all the Cryo-Chambers have gone offline as a result, including Chell's. Doug then attempts to run past the Turrets but is struck down.

Time for another flashback, this time set after GLaDOS has flooded the Enrichment Center with her neurotoxin. Rattmann, apparently the only survivor, is taunted by GLaDOS about his schizophrenia as he escapes from the main testing facility. While GLaDOS continues to taunt and manipulate him, Rattmann manages to reach the file room where he finds Chell's file, declaring that she's "the one", then puts her on top of the Test Subject list.

Back to reality, Rattmann is lying on the floor, wounded by the Turrets, reaches out to his Companion Cube but loses consciousness.

Another flashback begins, involving Henry having a conversation with GLaDOS. During the conversation, she tells him she has lost all interest in killing since she was fitted with a Morality Core and that she would like to perform a recreation of the Schrödinger's cat experiment during "Bring Your Cat to Work Day". She says that added to the boxes and the cats, she needs a little neurotoxin. Henry, unaware of her malicious intentions, accepts, "as long as it's for science", thus sealing the employees' fate.

Doug regains consciousness, and his schizophrenia has returned. The Cube can talk again and asks about Chell being "the one" and how Doug knew she is, to which he admits it was just a hunch. The Cube then tells Doug to patch Chell's Cryo-Unit in the reserve grid to restart her life support, which works but keeps Chell in an everlasting sleep until she is woken up, "both alive and dead until someone opens the box".

Exhausted, Rattmann crawls into the bed of a Relaxation Vault and presumably falls asleep. It was later revealed by Valve that Rattmann was long dead before the events of Portal 2^{[citation needed]}. On the floor, Chell's files scatter on the ground, showing that she should not be tested, as she is "abnormally stubborn and never ever gives up. Ever."

Portal 2

Main article: Portal 2

Single-player

Chapter 1: The Courtesy Call (Act 1) / Chapter 2: The Cold Boot (Act 2)

Following the events of Portal 2: Lab Rat, Chell is awoken 50 days later in her relaxation chamber, which has the appearance of a motel room, for a 'mandatory physical and mental wellness exercise'. After a brief 'exercise', Chell returns to her sleep. She is awoken an undetermined amount of time later (a pre-recorded message says "Hello, you have been in suspension for - NINE NINE NINE NINE NINE NINE NI-"), to the room intercom warning of an imminent core explosion. Her room is in a state of disrepair, and soon, an unfamiliar voice greets her. Upon opening the door she finds herself face to face with a more modern-looking Personality Core whose name is later revealed to be Wheatley, the jovial AI in charge of the test subjects storage facility. After warning Chell of the likelihood of her having serious brain damage, Wheatley moves her relaxation chamber through the storage facility, crashing several times and largely destroying the room in the process, all the while ranting about the huge responsibility of taking care of the test subjects. After successfully navigating the room to the main testing facility, Wheatley instructs Chell to go retrieve a "gun that makes holes," as it will be needed for their escape from the facility. Upon successfully acquiring the device, Wheatley and Chell make their way to GLaDOS' chamber where Wheatley claims an escape pod to the surface is located. They find the chamber partially destroyed, with overgrown wildlife everywhere, and in the middle of the chamber lies the lifeless body of GLaDOS. After reaching the breaker room under the chamber, Wheatley attempts to find the breaker for the lift. In the process, he inadvertently reboots GLaDOS. Bitter at the cause of her death, she crushes Wheatley and tosses him away before dropping Chell into the Emergency Intelligence Incinerator, into the incinerator room. GLaDOS instructs Chell to retrieve the Dual-Portal Device, before guiding her back into the facility's test chambers by navigating backward through Test Chamber 19. Fixing the broken down facility while Chell is once again put through testing, GLaDOS, bitter at her murder, informs Chell that her black box forced her to relive her own murder again and again forever.

Chapter 3: The Return / Chapter 4: The Surprise

When GLaDOS isn't watching, Wheatley pops out from behind a test chamber wall and reveals he survived their encounter with GLaDOS. He asks Chell to play along with the testing until he figures out a way for them to escape. GLaDOS' taunts become more vindictive, at one point pretending to reunite the 'orphan' Chell with her family. It becomes clear that Chell does not have much time left, as GLaDOS insinuates her usefulness is coming to an end. While in a test chamber, the power is cut out and Wheatley reveals himself from behind a wall panel, under the false impression GLaDOS cannot detect him. When she does, he and Chell make a run for it through the inner facility with GLaDOS attempting to halt their progress.

Chapter 5: The Escape

Along the way, they pass a 'potato power' exhibition, held on the ill-fated 'Bring Your Daughter to Work Day. While making their way through the Turret production facility, Wheatley reveals he plans to sabotage the Turrets and neurotoxin supply so that when they face GLaDOS she will be unarmed. They successfully carry out their plan by replacing the master Turret template with a Defective Turret and using portals to redirect a Thermal Discouragement Beam to cut off the neurotoxin supply lines. Hopeful, they make their way to GLaDOS' chamber once again for a showdown. GLaDOS, once again, attempts to kill Chell but is unsuccessful due to Wheatley's and Chell's sabotage. It is at this point that the Announcer informs them that the central core, GLaDOS, is 80% corrupt and because Wheatley is present, a core transfer is initialized. This requires both cores' approval, and when GLaDOS objects, a stalemate is reached. The Announcer informs them that a stalemate associate is required to press a stalemate resolution button for the core transfer to occur. GLaDOS desperately attempts to block Chell from doing so but is unsuccessful, and the core transfer occurs. Wheatley is transferred into GLaDOS' body and she is removed from power. In a jubilant mood, Wheatley sends Chell on her way to the surface. He begins laughing, but it becomes unusually powerful for Wheatley. He lowers Chell back down, going on about how he did it. GLaDOS taunts him, telling him that Chell did all the work, and in a fit of rage, he takes her core apart and places her in a potato battery. He tells Chell that he is the boss now and that she can no longer order him around. PotatOS is then shown off; Wheatley's attempt is to humiliate her. It is at this point GLaDOS reveals that Wheatley was designed to be a moron, in order to dampen GLaDOS' brainpower so that she wouldn't attempt to murder everyone in the facility. Angered by this revelation, Wheatley throws her in the lift with Chell and in a fit of rage smashes the lift downwards, where the lift floor collapses, and they fall into the depths of the facility.

Chapter 6: The Fall (Act 3)

Falling several miles down, Chell awakens to find herself in the very bowels of Aperture and the ruins of the old facility. She witnesses the potato GLaDOS being abducted by a bird before making her way through the ruins and entering through a closed-off area to find the old Aperture Science facility. A voice recording plays, welcoming the visitor to Aperture. The speaker introduces himself as Cave Johnson, founder and CEO of Aperture, and introduces his secretary, Caroline. As Chell makes her way through the old facility via enrichment spheres, Cave Johnson guides the player through the tests while gradually revealing the history behind Aperture. It is discovered that Cave Johnson founded the company in the 1950s as a curtain manufacturer, becoming a self-made billionaire, before expanding into a science research company. He built the facility in large salt mines beneath Michigan with the intention of competing with Black Mesa. In between lawsuits against his company for various mishaps and his personal rivalry with Black Mesa, who he claims stole much of his company's research, He built the facility in large salt mines beneath Michigan with the intention of competing with Black Mesa, Cave slowly runs the company into the ground.

Chapter 7: The Reunion

It is revealed that in a misguided move in the 1980s, Cave bought $70 million worth of moon rocks to grind up. The resulting gel was toxic, and Cave Johnson falls gravely ill. Chell is reunited with the potato GLaDOS, found in a bird's nest, and GLaDOS insists they need to stop the corrupted Wheatley before his actions cause the destruction of the facility. While traveling with Chell, GLaDOS comes across a portrait of Cave Johnson and Caroline, whom she finds vaguely familiar. She then finds herself unwittingly parroting a conversation between Caroline and Cave Johnson. Highly stressed, she manages to overload her battery and shuts it off temporarily. Cave Johnson's voice on the recordings now sounds frail and it is clear his health is quickly deteriorating. In a last-ditch attempt to survive, he instructs his engineers to start research into artificial intelligence, so that his mind can be transferred into a computer. Angry at the state of affairs, he instructs his employees that if he dies before the AI is complete, Caroline is to take charge of the facility, against her wishes. He also informs them that she can take his place in the AI. No more recordings are made, but it becomes clear that Caroline's mind was inserted into the AI, and is now a part of GLaDOS. Learning this, GLaDOS' attitude slowly changes. She begins praising Chell's progress and claims to have turned a new leaf. While making their way back up to the facility, GLaDOS observes a poster about robot paradoxes and comes up with a plan to stop Wheatley when they face him.

Chapter 8: The Itch (Act 4)

Chell, and GLaDOS return to find the facility in chaos. Several core meltdowns are in progress while Wheatley has been busy modifying the test chambers to his liking, including constructing Frankenturrets - crudely made walking Turret/Weighted Storage Cube hybrids. They confront Wheatley and GLaDOS attempts to shut him down by presenting him with a logical paradox. It fails as he nonchalantly provides a false answer, apparently too stupid to understand it. The Frankenturrets, however, short-circuit, humorously indicating that they are smarter than Wheatley. Having Chell and GLaDOS back in his clutches, Wheatley forces them to carry out his tests, revealing the need to test is an 'itch' hardwired into the AI system. Initially, Wheatley is satisfied with the testing but soon the euphoria of watching Chell and GLaDOS being tested wears off, as he builds up a resistance to the euphoric response. Growing frustrated with them, Wheatley hints he has found other test subjects (Atlas and P-body) and that he has a 'surprise to die for' coming soon. He unleashes his surprise early when Chell steps on a booby-trapped Aerial Faith Plate, which transports Chell and GLaDOS to a platform surrounded by spiked crushing plates.

Chapter 9: The Part Where He Kills You

Escaping the trap, Chell and GLaDOS make their escape through the inner facility, avoiding Wheatley's attempts to kill them. They come across a room containing rejected corrupted cores and GLaDOS formulates a plan. She stays behind to carry it out while Chell makes her way to Wheatley's lair for the final confrontation, where he reveals the facility will self-destruct in six minutes. They do battle and during its course, Chell manages to attach 3 corrupted cores onto Wheatley. This results in a core corruption of 100% and the Announcer intervenes to initiate a core transfer. GLaDOS inserts herself as the substitute core and hurries Chell to press the stalemate resolution button. Wheatley, anticipating this outcome, has booby-trapped the button and it explodes as Chell attempts to press it. She survives the explosion, to the disdain of Wheatley. With the last of her strength, she grabs the Handheld Portal Device and shoots a portal at the Moon's surface. The resulting portals cause everything in the room to be sucked into the vacuum of space, including Chell, but she manages to hang on by grabbing hold of the panicking Wheatley. GLaDOS uses a mechanical arm to detach Wheatley from his body, who is then sucked into space and pulls Chell back through before closing the portal. Chell wakes up later to find a worried Atlas and P-body watching over her and GLaDOS back in her body and back in charge of the facility. She thanks Chell for helping her find the Caroline inside her, before promptly deleting all traces of her. She reveals she has become weary of trying to kill Chell, and that the best course of the solution is to give Chell what she wants: her freedom. She sends Chell on her way to the surface, where along the way she is serenaded by a Turret Opera. Reaching the top, a door opens, and Chell steps out into a picturesque sunny cornfield where the door promptly shuts behind her. Taking in her freedom, GLaDOS surprises Chell by throwing out the Weighted Companion Cube she incinerated in Portal and the door down to the facility is closed shut.

The game ends with a wistful Wheatley floating aimlessly in space, admitting if he was able to go back, he would say he was sorry.

Co-op

The co-op campaign is set after the events of Portal 2's single-player campaign. In it, the two testing androids ATLAS and P-body of the Cooperative Testing Initiative carry out a series of tests in six different courses, each consisting of about eight or nine chambers. At the end of each course, GLaDOS sends the androids outside of the testing chambers and into the facility itself, claiming their help is needed to retrieve several Compact Discs "innocently" left lying around by the humans. In reality, she appears to be using the androids to help her gain control of the facility and gain information on "Area 219.32". After each out-of-chamber task, both androids are self-destructed and then reassembled in the Hub.

Calibration Chamber

The initial cooperative course whose main purpose is to 'calibrate' ATLAS and P-body for each other, as well as their own controls. During this course, GLaDOS implies the idea that most of this course is a competition of who is faster, as well as initiating her general attitude of creating friction between the two.

Course 5: Mobility Gels

With the previous courses finished, GLaDOS can now access a vault in the lower levels which contains hundreds of human test subjects. She has determined that, given their inability to die, Atlas and P-body just aren't the same as human test subjects. They are sent to open the vault. These final chambers take elements from all the previous test courses while adding the Aperture Science Mobility Gels as an additional element. In particular, the creative use of Hard Light Bridges and Excursion Funnels in conjunction with the gels is a necessary aspect of completing the test. Upon reaching the vault, ATLAS and P-body open it by making similar gestures to the camera installed on the lock. GLaDOS claims to have more work for them as she destroys them. As the credits roll, GLaDOS scans the identities of the test subjects and makes remarks about them, both positive and negative, though in the end the comments are apparently all directed at one subject.

Course 6: Art Therapy

GLaDOS rebuilds Atlas and P-Body, claiming that 100,000 years have passed since the conclusion of the 'Mobility Gels' course. She also claims (unconvincingly) that all of the humans are still alive. She guides the two of them through a new set of courses (which are supposedly designed to be art exhibitions), though a number of mechanical failures occur, which GLaDOS attempts to cover up.

At the end of Portal 2 Co-op Course 6 Chamber 4, the disassembly machinery fails, forcing ATLAS and P-body to make a detour through an incomplete test track. GLaDOS admits that she has been lying and reverses her original claim of the humans being fine, revealing that she has already killed them all during testing. She also comes clean that it has only been a week since the humans were "rescued," not 100,000 years.

GLaDOS believes that Chell has returned and has gained control of an old mainframe chassis, posing a threat to the facility. ATLAS and P-body spend the remaining chambers being "trained" as killing machines, though this merely involves solving further tests and being plied with generic insults. In the final chamber, GLaDOS informs the two that the reassembly machines have broken down and that if she doesn't regain control, their next deaths will be permanent.

The robots reach the chassis, but find that it is being controlled mindlessly by a crow nesting. Despite GLaDOS' calls for a retreat (due to her phobia of birds following her experiences as a potato), ATLAS gets the bird from the control panel and P-body manages to lock it out of the facility. GLaDOS then notices that the crow had been harboring three eggs, which she hatches in an "oviparous warming vault," planning to breed the chicks as "little killing machines". This reinforces speculation of using birds as test subjects as seen in Portal.

Trivia

• In order to flesh out the story in Portal 2, Valve originally intended to include an exhibition within the Aperture Science facility, one composed of different dioramas showcasing various aspects of the company and its philosophy. The dioramas were ultimately cut before the final release due to pacing issues and the Cave Johnson voice lines have replaced that level so the player can solve Test Chambers while also getting to know more about the old Aperture Science chambers and trivia.