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"These next tests require co-operation. Consequently, they have never been solved by a human. That's where you come in. You don't know pride, you don't know fear, you don't know anything. You'll be perfect."

ATLAS and P-body, referred to as Blue and Orange by GLaDOS, are a pair of bipedal Personality Construct-based androids that are the main protagonists in Portal 2’s cooperative campaign.[3]

Designed by GLaDOS sometime during the single-player campaign, they are to complete the Cooperative Testing Initiative in the Aperture Science Enrichment Center, previously uncompleted by human Test Subjects.[4]

Gameplay-wise, ATLAS is played by the host of the co-op session (the player who sends an invitation), while P-Body is played by the guest (the player who accepts an invitation). PlayStation 3 players are automatically assigned as the host during cross-platform games, to prevent the use of the console by the PC player.



Portal 2[]

ATLAS, P-Body and GLaDOS Portal 2

ATLAS, P-Body and GLaDOS as Chell wakes up after sending Wheatley to space.

GLaDOS mentions that she had been working on the Cooperative Testing Initiative before Chell escaped, (it is assumed she means the second escape, when Chell escaped with Wheatley, as she says "It was nothing personal, but you DID kill me, fair's fair.", showing that she could not have meant the first time Chell escaped in Portal).

While Wheatley was in control of the Aperture Laboratories facility, he discovered the C.T.I. and decided that he no longer needed to keep Chell and GLaDOS alive for further testing, as the replaceable robots could serve in their place, leading him to try to kill his current test subjects. After Wheatley is forcibly removed from control, GLaDOS comes to much the same conclusion, finally giving Chell her freedom (and her original Weighted Companion Cube).

Portal 2 Co-op Campaign[]

Following Chell's exile from Aperture Laboratories, GLaDOS begins testing on ATLAS and P-body. They are sent through a series of test courses designed to prepare them for the final chamber which takes place in the abandoned basement of the facility. Over the course of their testing, GLaDOS tries to drive them apart in various ways, only to fail each time. She eventually concludes that they simply lack the capacity to betray each other. For their final test, ATLAS and P-body are sent to unlock a vault containing hundreds of humans in stasis, since GLaDOS has determined that testing with robots (which can't die) just isn't the same as human testing, although she tells them there is still much work for them to do. She then explodes them and brings them back for testing.

Portal 2: Peer Review[]

GLaDOS reassembles ATLAS and P-Body, informing them that they are 100,000 years in the future, where testing is just a form of art. After they explore several of her "exhibits", the disassemblers break down and she reveals that it's only been a week, all the humans are dead, and someone else has plugged themselves into an old GLaDOS chassis and is trying to take over the facility.

Portal 2 coop jan 22 8

P-body jumping through a portal with a Weighted Pivot Cube.

As the facility continues to break down, GLaDOS tries to turn ATLAS and P-Body into "killing machines" by provoking and insulting them. Even though this fails, she sends them to inspect the old chassis anyway and murder whoever has taken it over, because the reassembly machines are failing.

ATLAS and P-Body enter the old chassis room to find that the bird from the single-player campaign is making a nest in the chassis. Although GLaDOS, suffering from a phobia of birds, urges the robots to retreat, they succeed in shooing the bird out of the facility. GLaDOS then hatches the eggs in a specially-built relaxation vault, and begins to treat the newborn birds as test subjects, observing that they are the perfect "killing machines".


P2 robots blueprints1

ATLAS and P-body blueprints, as seen in the video Aperture Investment Opportunity #2: "Bot Trust".

The robots were designed from scraps. ATLAS' design is based on a Personality Core, while P-body is based on a Sentry Turret. Both had cores that were originally used in scientific calculators.[1] To facilitate their humanization, they were given their own personalities, and clearly anthropomorphic designs and behaviors. Gender-wise, the robots have their own genders, as stated by Chet Faliszek in an interview (ATLAS as male, P-body as female).[5]

Each robot has its own Aperture Science Handheld Portal Device that bears the color of its user (blue for ATLAS, orange for P-body), as two lines running along the barrel. Each robot's portal gun produces two distinct colors of portal (ATLAS' are blue (primary) and violet (secondary); P-body's are yellow (primary) and red (secondary)). Both pairs of portals can exist at once, and either can pass through each other's portals, a vital means of completing the tests. They are respawned through Vital Apparatus Vents if destroyed. Duplicate robots are constantly built by automated machines, apparently keeping the memories and behavior of the previous incarnations.

Their heads function independently of their bodies, allowing them to control their limbs even if it is removed. This aspect of their design allows them to play pranks on each other by taking or knocking off their heads.

Personality and skills[]


ATLAS hugging P-body after the latter's reconstruction.

As said above, the robots were designed with anthropomorphic personalities to facilitate their humanization. These personalities are expected to develop during the course of the game.

Examples of anthropomorphism go from simple to complex behaviors. For instance, the results of the Aperture Science Collaborative Disposition Test tell that ATLAS is brave and fearless, willing to take on any challenge, while P-body is inquisitive and sensitive, examining the situation with care before proceeding, however, the co-op intro shows the opposite. Both value friendship, making them the ideal testing partners.

Other anthropomorphic behaviors include making gestures to each other to indicate the other what to do or where to go, using some form of speech embodied by an apparently unintelligible robotic chatter (ATLAS having a masculine voice, P-body having a more feminine voice), using portals for fun and not only for testing, using some form of laughter, playing rock-paper-scissors, or hugging each other.[6] Co-operative work also requires them to trust each other, and they also undergo tests for that purpose and eventually will tend to develop a tendency to betray each other like humans would do, and in the end trust each other only 6 seconds longer than humans.[7]

The skills and personality are obviously influenced by the players' behavior toward each other. Tests or achievements require being selfless as much as being selfish.

Behind the scenes[]


ASCII art image of the first revealed concept art of the robots, shown during the Portal ARG.

  • ATLAS and P-body, along with the Cooperative Testing Initiative, were first introduced during the Portal ARG, in one of the ASCII art images given by the BBS. In that image, actually concept art for Portal 2, ATLAS is holding an Aperture Science Handheld Portal Device, and they hold each other's hands: this gesture is said to be a sign of innocence more than an indication of romance between the two, and also describes the whole co-op idea, that Portal 2 also means playing with a friend.[1] The ARG also revealed through the Aperture Image Format program two images referring to the completion of the trial phase of the Aperture Science Cooperative Testing Initiative, referring to Portal 2’s co-op mode. Their second appearance is at the very start of the "Portal is Free" video promoting Portal being free from May 12 to May 24, 2010, where they can be seen within the isometric offices in a small room on the bottom right. They then appeared in a teaser for the co-op mode of Portal 2 shown at Gamescom 2010, in a dramatized version of an example of co-op gameplay, where ATLAS elbows P-body so that it subjects itself to ATLAS's portal to be sent thanks to momentum to a button located beyond a trap and allowing the completion of the Test Chamber. In the video, they appear to use some form of speech, consisting of computer-like sounds. They then appeared in the full version of the co-op trailer and other variants of it, and weekly videos leading up to Portal 2's release, such as a TV spot, Aperture Investment Opportunity #1: "Panels", and Aperture Investment Opportunity #2: "Bot Trust".
Atlas P-body first

First revealed concept art.

  • Originally, the two Portal 2 co-op characters were to be human females, with player one being Chell, and player two being a new character named Mel. They were replaced by robots in order to create an in-universe reason for the characters respawning after death,[8] and making them the first playable robot characters in the Half-Life universe.
  • As seen in other concept art images, the two robots have come through several other iterations, including color variants, and more humanoid appearances,[9] with influences from the film Westworld, as the team at some point wanted them to look human and feel robotic at the same time.[1] As seen in more recent concept art, they also originally both had a red eye, later changed to blue and orange for ATLAS and P-body, respectively.
  • The robot names are apparently a reference to their body shapes, though this has not been confirmed yet. ATLAS may be related to the Titan of the same name, which is often represented as supporting Earth on his back, a task which would be eased by the size of ATLAS' shoulders, another way it could be represented is the fact that both the Mythical Atlas and ATLAS carry a spherical object, the mythical one carries the earth, while ATLAS carries a personality core. "ATLAS" being written in caps, this may also be an acronym of a currently unknown significance. P-body's name, meanwhile, refers to a label on its back describing the robot's 'Frame Type' as 'P'. It may be a pun on "pea body", the robot's body shape somewhat resembling a pea pod.
  • The robots are referred as "ballbot" (ATLAS) and "eggbot" (P-body) in game files.
  • Three custom skins are available for those who pre-ordered or buy the retail version of Portal 2, depending on the place of purchase.
    • Roll Cage (featured in the informational video Aperture Investment Opportunity #2: "Bot Trust"): pre-ordering through GameStop (USA) or EB Games (Australia).
    • Paint Job: pre-ordering through Amazon.de (Germany), Amazon.fr (worldwide) or CDON.com (Sweden, Denmark, Norway, Finland).
    • Antenna Topper: pre-ordering through Fnac (France), Webhallen (Sweden), Alcom (Swiss) or Softridge (Swiss), buying retail version in Russia or CIS.
  • Several unused P-body textures can be found in Portal 2 game files: white dirty, white clean, blue and red, possibly used by placeholder robots model (not existing in game files). The red light can be seen on the textures.
  • The original idea for their robot appearance was to have them identical. This idea was scrapped early in development in order to add a more creative style to them. This made them look less like two machines and more like two friends, thus making them more human-like while with different significant features, directly identified by Valve as a close homage of Laurel and Hardy.[source?]


  • P-body makes a cameo appearance during the single-player campaign, in Chapter 8: The Itch. In Test Chamber 15 of Wheatley's Testing Track, Wheatley attempts to make an exit chamber for Chell, P-body can be seen briefly by the exit before realizing she can be seen and running through it.[10]
  • ATLAS' portal colors are similar to the colors for Chell's ASHPD.
  • In the developer commentary, it is stated that ATLAS was constructed well before P-body. Moreover, it's explained that their designs reflect their age. Where ATLAS displays an abundance of supports, a sturdier, albeit clunkier and messier design. P-body's design in comparison is considerably cleaner and more streamlined, indicative of a newer build.
    • Additionally, P-body is seen displaying what has been referred to as a "pee-pee dance" where she bobs from side to side in order to maintain her own balance. The commentary describes this as a deliberate design choice by GLaDOS.
  • The scene in the Bot Trust video where ATLAS smashes himself with a frying pan is a reference to the pancake-flipping robot arm.
  • One of the acid death animations for ATLAS is a reference to the movie, Terminator 2: Judgment Day, as when he falls in acid he will sometimes stick up his thumb as he sinks, similar to what the Terminator ( who is also a robot) does at the end of the film.
  • Atlas is male, and P-Body is female. They have male and female voices, male if Atlas, and P-body, as feminine.
  • ATLAS has a personality core inspired design for his base, and P-Body has a turret inspired design.
  • P-Body used to have red eyes, making her even more related to the turrets.
  • In the events of Portals 2's ending cutscene, wee see ATLAS, and P-Body checking up on Chell. It is unaware if they helped Chell in anyway, although knowing them, they might actually have.



Concept art[]



List of appearances[]


Imagecat The Half-Life Wiki has more images related to ATLAS and P-body.

External links[]