Story

Throughout the Portal series, you take on the role of Chell, a young woman trapped within the Aperture Science complex. Chell is forced to solve tests of varying difficulty in chambers designed by an AI-gone-rouge named GLaDOS. During the early stages of the games, Chell is granted access to the Handheld Portal Device, a piece of equipment developed by Aperture Science that allows Chell to create portals that are large enough for her to travel through. These portals 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 Handheld Portal Gun. 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. Motivating Chell 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 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 neurotoxins. GLaDOS now attempts to do the same to Chell. Using the Handheld Portal Device, Chell defeats GLaDOS by removing her AI 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 awakes 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.

Portal: Still Alive

Main article: Portal: Still Alive

Portal: Still Alive is a Xbox 360 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.

Portal 2

Main article: Portal 2

Portal 2 was released simultaneously on PC & Mac, Xbox 360 and PS3.

Single player

Chapter 1: The Courtesy Call / Chapter 2: The Cold Boot

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 asleep for - NINE NINE NINE NINE NINE NINE NI - days."), 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 Personality Core who introduces himself as Wheatley, the jovial AI in charge of the test subjects storage facility. After bringing Chell up to date, Wheatley moves her relaxation chamber through the storage facility, crashing several times and almost destroying the room. After successfully navigating the room to the main facility, Wheatley instructs Chell to go retrieve the Handheld Portal Device, 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 a lift 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. Navigating to 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 Handheld Portal Device, before guiding her back into the facility's test chambers. 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 for thirty millennia.

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 use 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 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 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 deep into the depths of the facility.

Chapter 6: The Fall

Falling several miles down, Chell awakens to find herself in the very bowels of Aperture and the ruins of the old facility, before witnessing the potato GLaDOS being abducted by a bird. Chell makes her way through the ruins and enters 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 testing 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 1950's as a curtains 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. Inbetween lawsuits against his company for various mishaps and his personal rivalry with Black Mesa, who he claims stole much of his company's research, Cave Johnson slowly runs the company into the ground. It is revealed that in a misguided move in the 1980's, he 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.

Chapter 7: The Reunion

While travelling 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 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, and Wheatley, GLaDOS observes a poster about robot paradoxes and comes up with a plan to stop Wheatley when they face him.

Chapter 8: The Itch

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 immune to its effect. 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 (P-body and Atlas) 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, but Chell 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 P-body and Atlas 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 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 has one last surprise. The Weighted Companion Cube she incinerated in Portal is thrown outside with her and the door down to the facility is closed shut.

The game ends with a wistful Wheatley floating aimlessly in space, admitting that he regrets his actions.

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.