Story

The Portal series is story-driven, and as such the scenario takes an important place in the gaming experience.

In the games you play Chell, a young women stuck in an Aperture Science complex forced by the Artificial Intelligence GLaDOS to solve tests in specialy designed chambers using for solving them the Handheld Portal Device.

Portal
The game has two distinct acts, the test chambers and the escape.

Act 1: The Test Chambers
The game begins with the player awakening in a Relaxation Vault where they are briefed by the disembodied voice of GLaDOS before being released through a portal. The player is introduced to the testing process and mechanics, eventually culminating in the procurement of the Handheld Portal Gun. As Chell makes her way through test chambers it becomes clear Motivating Chell with the promise of Cake at the end of the testing, Chell is put through tests of increasing complexity.

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

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 appearence of a motel room, for a 'mandatory physical and mental wellness exercise'. Returning to her long sleep, she is awoken an undetermined amount of time later by an unfamiliar voice at the door to find the room in a state of disrepair and the room intercom warning of an imminent core explosion. 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 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's chamber where Wheatley claims a lift to the surface is located. They find the chamber partially destroyed and 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 inadvertently rebooting 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 forced her to relive her own murder for decades.

Chapter 3: The Return / Chapter 4: The Surprise
While in a test chamber, when GLaDOS isn't watching, Wheatley reveals he survived their encounter with GLaDOS and asks Chell to play along with the testing until he figures out a way for them to escape. GLaDOS's 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's 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's body and she is removed from power. In jubilant mood, Wheatley sends Chell on her way to the surface before having a change of heart as he revels in his new found position of power. GLaDOS taunts him and in a fit of rage he takes her core apart and places her in a potato battery. It is at this point GLaDOS reveals that Wheatley was designed to be an 'idiot', in order to dampen GLaDOS's 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 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, who 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 revealed 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 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 $70m 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 nest, who 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 large 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's 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. It fails as he nonchalantly provides an answer, apparently immune to it's effect. 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 it 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, regretting his actions