Chapter 1: The Incinerator
The game starts with Mel exiting the human vault for testing, but as she has been stored since 1952, she is slightly unstable. GLaDOS has completely redone the first 10 chambers of Test Track A (Portal 1). The place is still destroyed and overgrown quite a bit. The more tests Mel goes through the more her vision and aim of the Portal Gun become off-track. In Test Chamber 08, GLaDOS is distracted by her supervisor who is telling her that the new wing of the enrichment center that was almost completely destroyed by Wheatley has been tested as safe. However, as this is happening, Mel passes out, due to her being unstable from her stasis. GLaDOS sees this and orders her supervisor to transport her to the human incinerator. The scene begins to fade away as Mel begins to be dragged out of the chamber by the supervisor.
Mel wakes up on a moving platform edging toward a fire pit. Her Portal Gun has been taken off of her and she is here to die. But, she escapes through a broken gap in the wall and navigates her way through maintenance corridors that linked to the observation rooms observing the now dilapidated Test Chamber 19 of Test Track A. It's been abandoned by GLaDOS, who is now working on an entirely different part of the facility.
Mel finds elevator controls, controlling the pneumatic diversity vent controlling chamber 19's elevator. She directs it down to chamber 00 and gets into the elevator. Upon arriving, she walks through the abandoned chamber and gets into the relaxation vault after the portals open when detecting a lifeform outside the vault. Mel gets inside and lays in the relaxation pod. It closes, putting her into relaxation until further notice.
Chapter 2: Dilapidation
After 16 years, the relaxation pod power has been completely destroyed and Mel is forced awake by emergency protocols so she doesn't die in eternal sleep. The test chambers are even more destroyed than before, but she manages to get her way to Chamber 08 until the entire floor in front of the exit collapses and Mel finds herself in an office corridor. Getting through, she comes across a personality construct who's management rail out of the office corridors is broken. Mel gladly helps this core, Terry, out of the office corridors. Terry's voice sounds familiar. Does Mel know him?
There is an optional segment that Mel is able to go through, behind a broken wall is a pneumatic diversity vent entrance that's turned off, approaching it will cause Terry to deny any access to it, but if Mel were to stay there longer, he finally gives in and turns on the vent taking him and Mel into it. The two are then transported through the same tubes that Chell and Wheatley were in during the escape in Portal 2, but everything in this section of the facility is broken and abandoned. The two find themselves in a maintenance room but going further finds them in an office corridor. There's a broken bridge to GLaDOS' old central core. They both go in and Terry is glad to find that GLaDOS' old body is also here, but her head is missing. Possibly meaning that she has a brand new body. He activates an elevator in the old core room and they both descend downward and the two find themselves in an office they would have ended up going through anyway, Mel hops out of the elevator that is in a vent by the wall and it closes and ascends back up.
In this office are elevator controls for an old elevator at the back. Terry messes with the controls and he redirects it upward into the more modern facility that GLaDOS still controls. Mel rises up into an office segment gets her way through some more office corridors, alongside her new friend, Terry. They then stumble across the massive facility, looking as better as it was 16 years ago! The two can hear GLaDOS mocking and talking to test robots she uses for testing, they're not as good as humans though, but they're good enough. Terry directs Mel toward a control room for Test Track 5. He says to her that the test chambers have a strong firewall, and that getting through it would prove to be tough. Thus, he puts Mel through Test Track 5. After multiple chambers with Terry commentating over, later test chambers that are still under construction then become easier, panels moving to make it easier for Mel to complete the tests with her Single Portal Device. Terry is confused by this, but goes along with it.
Terry manages to get Mel out of an incomplete test chamber and onto a catwalk outside the track close to the ceiling of the enrichment center. He opens a door into an old office with a vent elevator up to older areas of the upper offices. He bids farewell as Mel rises up to Upper Aperture.
Chapter 3: The Ascent
Mel rises up into a modern-looking office. Exiting through a maintenance door, she finds herself inside an old junkyard. She opens a giant quarantined vault door. Mel activates the power in Test Shaft 10 labelled 'Lima Whiskey. Mel finds some offices that then begin tests in enrichment spheres. A detector detects that Mel has contraband (the Single Portal-Gun) and must hand it in. She does so and the doors then re-open. Whilst she approaches the elevator upward, she is given a new Portal Gun, similar to the Portal 1 design, but it is a dual one, and can shoot both blue and orange portals.
Upon entering the offices, it's furnished quite classically with a painting of Cave Johnson from the 1980's before died. Cave Johnson suddenly begins speaking off of recordings aiding you through the test shaft. On the side of the shaft are years. It goes all the way up to 1996 in this shaft. When reaching the 1984, all recordings from then on are not of Cave Johnson, but of his assistant, Caroline.
After going through four enrichment spheres testing mechanics such as pneumatic diversity vents, excursion funnels (with a different look to the modern ones) and high energy pellets, Mel manages to get out of the enrichment shaft and into the maintenance areas of Upper Aperture. Mel activates power in all the maintenance cores within Upper Aperture, upon doing so however, she then also activates an intrusion artificial intelligence designed to protect the Aperture scientists.
The voice begins to speak about an "Organic Lifeform detected in C-SECTOR MAINTENANCE CORE" and begins to track Mel's every movement. The more and more Mel gets closer to the control core in the C-SECTOR the more her threat level begins to slowly increase. When in the control room, Mel activates an elevator out of Aperture forever. However, seeing this, the voice then sees this as her running from doing something guilty, such as killing all of Aperture's scientists... The elevator stops and begins to move back down to the control room and Mel's threat level immediately shoots up to 150%!
Mel presses a button that says "REACTIVATE EMERGENCY ELEVATOR EM TETHERS" but it was a hoax, it in fact gives the voice full control to the enrichment center below by tapping into GLaDOS' control. The elevator opens again but goes down into a room with a more modern vent elevator back down to the enrichment center. Mel steps into it, and decends back into the enrichment center...
Chapter 4: Back to the Enrichment Center
Mel begins to slowly descend into the enrichment center, suddenly, test chambers on their tracks begin to suddenly move out of place, as the voice then says "Artificial Lifeform detected in TESTING CORE #42" and then "Artificial Lifeform threat level increasing to 100%... shutting down lifeform". The voice tries to shut down GLaDOS but she manages to resist and not shutdown.
Mel ends up in Test Track 6 which begins to get slightly rearranged by the voice above. A new testing element known as the 'Destruction Fizzler' is introduced, nothing (including lifeforms) is allowed to pass through. It's a laser field and fizzler in one! GLaDOS does a quick scan of the voice and ends up knowing of it's name: AEDAS (Aperture Employee Defense Artificial System). GLaDOS constantly tries to help you out of the Test Track. In Chamber 22, GLaDOS distracts AEDAS by beginning to move Test Chambers on an entire different side of the facility. This gives her the chance to open up the side of the chamber and let Mel out on a light bridge.
On the catwalks, AEDAS immediately notices this activity and then smashes another chamber into the side of Chamber 22. The light bridge stops working and there's no way back now. AEDAS begins to torment Mel, dispensing Turrets, Rocket Turrets and even trying to gas her with Neurotoxin. AEDAS begins to give up on the neurotoxin as he is overusing it and begins to push Test Chambers in her way for her to complete and slow her down. Mel gets past them all that pass and eventually finds the outside shell of GLaDOS' core. It's a massive octagonal shaped shell with the main core on the inside. As Mel approaches GLaDOS' core, test chambers begin moving on their tracks by AEDAS because he's trying to crush Mel to death. Luckily, she gets out just in time and gets her way inside the central core of the enrichment center.
Inside the octagonal shell is a central core that is extremely reminiscent of Wheatley's core, just advanced and actually useful. AEDAS has almost no control in this shell and it should be relatively safe. GLaDOS gets Mel to use all three gels to make her way inside of the control core. When inside she finds herself under on catwalks toward the elevator in the old breaker room, which has been relocated. GLaDOS raises this elevator so Mel is in the core and gives her a transceiver to put on her portal gun so she can communicate with her when out of her reach. She hurries Mel into an elevator and she begins to descend downward to Test Shaft 09 so that she is safe.
Whilst going down, AEDAS redirects the elevator from Test Shaft 09 all the way to the abandoned parts of Aperture that GLaDOS has no control over anymore, but surprisingly AEDAS does. AEDAS puts Mel onto a moving platform toward the incinerator in Test Chamber 19. GLaDOS mocks AEDAS for thinking that Mel was too stupid to escape. She escapes (to no surprise) and ends up following catwalks behind areas no one has any power over. She finds her way inside a test chamber through a wall and is inside the room with the Emergency Intelligence Incinerator in Chamber 17. GLaDOS says it's the only way out, Mel activates it and thankfully it's not working. She drops down a deep hole into a junkyard by Test Shaft 01, 'Cromo Triton'.
Chapter 5: The Descent
Mel descends into an abandoned junkyard and finds her way through the burnt rubble. There are easter eggs here including an old burnt rocket turret and even a radio playing a rock version of 'Want You Gone'. Mel finds herself at the very bottom of the Test Shaft. She activates the tests, with GLaDOS over the transceiver still struggling with AEDAS who is now fully tormenting her. Nonetheless, GLaDOS tries as hard as she can to help Mel through the Test Shaft.
Mel gets into an enrichment sphere, it's extremely damaged though, there is hardly any goo near the bottom and the top is completely broken open. The test chamber in the sphere is completely dilapidated and testing cannot be done. Mel gets through and climbs down the sphere's steel and concrete struts. She gets into a control room where she activates all the power in the Test Shaft. Doing this however, caused an explosion on the damaged sphere's struts and it collapses into the shaft, taking the rest of the spheres with it.
The power also activated emergency maintenance elevators, allowing Mel to elevate downward into a maintenance area that connects to Test Shaft 02, 'Gerus Photon'. Here, Portal testing isn't being done, but testing for thermal discouragement beams and the discouragement redirection cube. But, because of the dilapidation, portals must be used to direct the beams in ways they weren't originally supposed to. Mel activates a pump station known as 'Delta'. She activates it and a new gel known as 'Reflection Gel' that reflects lasers pointed toward it is pumped into the enrichment spheres. Mel gets here way inside one by climbing across the pipe.
After 5 of these enrichment spheres have been completed, Mel descends down the elevator of the last one but the lift falls out of it's shaft and Mel falls deeper into the Test Shaft and lands onto a support beam. Mel climbs over to the side to find yet another control room. Mel finds her way into a maintenance corridor leading toward the bottom of the shaft. Behind some gel flow pipes and grated wall is a giant vault. Mel gets the pipe and stuff out of the way by collapsing an entire observation room above onto it. After this, she opens the giant vault with a switch in a control room that not only opens the vault door but also bugs out and allows access for all AIs in the enrichment center to have access to the Test Shafts!
Mel walks through the giant vault, hearing AEDAS' voice once again occupying GLaDOS' too. She makes haste into a pipe maintenance room. It's large and filled with gel and water flow pipes. AEDAS cranks up the water pressure to the point where it breaks the pipes and he begins to flood the Test Shaft and plans to flood the entirety of Aperture Science: Innovators and the enrichment center above! Mel finds an old door that gives her access to the old salt mines that Aperture was built in. She gets in and ventures forward!
Chapter 6: The Salt Mines
Stepping into the old Salt Mines, Mel is told by GLaDOS that she has maps of the entire underground mining facility. She tells Mel that there is another exit from the mines that was never closed off. Water begins to slowly rise upward as Mel avoids obstacles and blockages. GLaDOS, being tormented by AEDAS, is able to tell Mel to beware as she has reports in her files about a freight train that vanished just before the Salt Mines were abandoned. It was labelled '43-D45'. Mel continues forward and ends up coming across this very train, it's completely on it's side, collapsed by rocks from the ceiling, allowing a shortcut toward the exit.
Shakes in the ground from above keep occurring. GLaDOS tells Mel they have a day to live before the 'CORE' explodes as AEDAS has took complete control of it. She has calculated that the explosion would reach a 10km radius around the facility, destroying everything with the explosion, including AEDAS itself, whose intelligence is obviously too low to realise what it's actually doing as it's protocols are making it focus on destroying GLaDOS and Mel over it's own protection. Even if Mel would escape through the Salt Mines, she would surely be killed by the dark energy reactor's explosion.
GLaDOS encourages Mel to return to the enrichment center to regain control of the CORE using a fail-safe that activates emergency coolers in case the heat raises excessively, and AEDAS is doing that right now! Mel manages to find an entrance to Test Shaft 9 in the vitrification shaft Chell fell into back in Portal 2. Going inside, the shaft is much more modernized and GLaDOS is now able to speak over the intercom instead of a transceiver.
GLaDOS says that because the modernization of this shaft is still incomplete, Mel will have to go through the enrichment spheres testing the High Energy Pellet as GLaDOS has moved all testing of gels into Shaft 8 which is also modernized along with 7 and 6 with 5 being planned. After going through all 10 enrichment spheres, Mel gets to the top of the shaft and finds her way into the enrichment center through an elevator as more quakes are shaking the ground. She rises into the enrichment center once again to now activate the fail-safe within the CORE...
Chapter 7: Complicated Competition
Mel rises into an office that is hardly ever used by GLaDOS, she gets onto the catwalks and begins to make her way toward the CORE in the distance, a giant metal structure in the distance converting dark energy into electricity. The air around the CORE is waving as it is slowly and slowly heating up and is ready to explode at any given moment. Mel goes through Test Track 234 which has been completely edited by AEDAS, making it much harder.
After going through the Test Track and edging closer to the CORE, GLaDOS evacuates Mel from the track to the nearest catwalk that gives Mel access to the CORE. GLaDOS sends a special Activation Mechanism that will activate the fail-safe. Mel goes into the CORE and GLaDOS suddenly stops speaking, worrying her. However, to Mel's surprise, Terry was there to meet her! Terry guides her through the CORE, deactivating traps set up by AEDAS using his terminal functions. AEDAS then begins to make makeshift test chambers and is making makeshift vents and pipes transporting objects around the centre. Terry says that AEDAS is doing this because he is suffering from the euphoric test feeling as he has tapped into GLaDOS' control, meaning that he gets an itch when he doesn't see any tests completed.
After completing a bunch of tests in the CORE that Terry couldn't have any control over, Mel finds a control room with an elevator. She activates the fail-safe and the CORE begins to cool down. However, AEDAS, pretending to be GLaDOS, leads Mel into an elevator. This elevator however, leads Mel straight to GLaDOS' Central Core Chamber! She rises up into the maintenance areas in the octagonal shell around her chamber. Mel is lead over a large gap through an excursion funnel placed by AEDAS. The octagonal shell is now being filled with test chambers along with the main central core. Mel goes through the same way she got into the chamber earlier before falling into shaft 01.
She confronts a monstrosity; GLaDOS has become completely delusional because AEDAS has forced brand new 'AEDAS Control Constructs' onto GLaDOS as if they were personality cores! They give AEDAS complete control of GLaDOS and everything she is able to do. GLaDOS attacks Mel as AEDAS has completely brainwashed her. Mel fights back. This fight is a kind of combination of both final fights from the previous Portal games. You have to use bombs that she fires to break pipes and stuff to allow Mel to hit her with them and get the AEDAS Cores off her and put them in the incinerator. GLaDOS can still talk to Mel over the transceiver as it is her conscience that is left that is speaking over it. Mel fights GLaDOS, hitting her with bombs to knock the cores off and incinerating them. After all of them are completely destroyed she is finally in control of everything. She manages to use her elevator to get Mel back into the control room in Upper Aperture she was inside before being taken back down by AEDAS. Who would have known that this elevator was actually connected to that room?! GLaDOS even says she didn't even know it was connected either! When Mel rises up, the room is much more destroyed and the elevator she tried to use is out of service. Mel finds a way out of the room and into the maintenance corridors of Upper Aperture...
Chapter 8: Intrusion
Mel gets into the maintenance areas of Upper Aperture. She gets her way into Test Shaft 12, 'Ingrid Prestige'. She goes through a few of the enrichment spheres before finding a way A-SECTOR MAINTENANCE CORE. AEDAS' server room is located inside this core. GLaDOS gives instructions to Mel to find her way through the core while AEDAS constantly tries to stop her. While in the maintenance core, Mel comes across an observation room looking over a room with broken screens that are flickering with pictures of a wheat field on them. There is also a fake wheat field with a dilapidated companion cube and a skeleton in an Aperture jumpsuit. GLaDOS begins to freak out and breaks down. She explains to Mel that the skeleton is that of someone who helped her... albeit with violence but helped her regain her 'real' consciousness, that of Caroline. She said she didn't know that that elevator she sent Chell up in would actually end up in a dead end.
GLaDOS recollects herself and manages to direct Mel into the turret production line that AEDAS uses and tells Mel it would be impossible for AEDAS to pump up the turrets in the enrichment center up to his central core. Mel shuts down the turret production, dodging the turrets in the meantime. GLaDOS also gets Mel to open up the vault to AEDAS' core by going into a security room and overthrowing AEDAS' control. Mel couldn't do this before as there were turrets in her way, but now because the program has recieved a notification about production shutting off, all turrets that were originally deployed have been put back into storage until production is reactivated.
Mel overthrows the controls and the giant vault door opens. Mel gets inside and AEDAS suddenly goes awkwardly quiet. There is a control panel in the extremely large room. Mel sees a button that says 'ESCAPE'. As if Mel would fall for that again? Mel begins to walk out of the room until the door shuts and AEDAS forces her to press it. Pressing it activates AEDAS' physical form. A giant spherical core hanging from the ceiling with a blue eye. Four electric lasers lifting up a giant ring with four personality cores on it. Without this ring, AEDAS is unable to function.
Using gravity, Mel manages to fling herself onto the first core, a 'DATA Connection Core'. This core allows AEDAS to connect to more advanced protocols. Mel destroys this first one and one of AEDAS' lasers shuts off. Using aerial faith plates, Mel gets onto the second one, a Curiosity Core. She destroys this one too and another laser shuts off. At this point AEDAS begins to use pellet launchers and lasers to attack Mel.
Mel uses multiple gels to get to the third core, a... Wheatley?... Wheatley is pulled off and instead of incinerating him Mel instead puts him into a pneumatic diversity tube that leads into the enrichment center. It's one way so AEDAS wasn't able to pump anything up using it. After getting out AEDAS' reach, the third laser shuts off. The final one, another DATA Core is pulled off using excursion funnels. After incineration, AEDAS is seemingly shut down as the ring falls off...
As Mel goes toward the newly opened door to the server rooms, it immediately closes! AEDAS immediately reactivates and his eye turns red. Giant arms break through where the lasers used to be and it forcefully grabs the ring, reactivating AEDAS properly. The ring's blue lights also become red. Using gravity, Mel is able to fling herself on top of AEDAS' main spherical core. There is a normal door here to AEDAS' manual controls, revealing why this artificial intelligence was built. AEDAS was built to ensure the safety of all Aperture employees and is to destroy any threats to them. Connected to the mainframe is another core, an anger core! Mel takes it and incinerates it and AEDAS' fierce and more advanced form shuts down forever, leaving all controls and protocols to manual control.
The door to the server room opens and here, Mel switches the controls and GLaDOS finally has full control of the entire facility, Aperture Laboratories... Aperture Science: Innovators... even the Upper Levels of Aperture! AEDAS' files are deleted forever and AEDAS will never be reactivated ever... Mel passes out because of all the stress she just went through
Mel awakes in an elevator in GLaDOS' Central Core and GLaDOS thanks Mel for all she has done. Now that AEDAS has been deactivated and deleted forever, GLaDOS has full control of the facility, and more science can be done. She even admits that she was observing Mel and Terry when Mel first ascended upward, which explains the moving panels and etc within Test Track 5 as Terry was unable to control them. Then, on a core management rail, Wheatley comes in and explains that there were astronauts that found him and the space core. The astronauts shuttled Wheatley and Space Core back to the location of the enrichment center, seeing Aperture Science written on them. AEDAS received the shuttle as he was closest to the surface. AEDAS attached Wheatley to him thanks to the Curiosity Core... and Wheatley made AEDAS an idiot, doing stupid stuff, like blowing himself up along with the enrichment center! Space Core was thrown away because attaching Wheatley managed to encourage AEDAS to do just that. Terry also comes in and recollects the time when Mel found him in the offices... and when Terry came across Mel in the CORE. He bids farewell along with GLaDOS and Wheatley. Mel rises up back into that control room with the elevator in Upper Aperture. Mel steps into the elevator and she rises to the surface...
Mel steps through a small door with a valve on it. She walks through and looks back at the damaged facility behind her. She then sees robots already beginning to reconstruct the exterior. Mel sees an advanced city in the distance, she travels toward it to restart her life. And be away from Aperture Laboratories... forever...?
Chapter 9: The Advanced Testing Initiative
A year later in the now rebuilt and advanced society of Earth, Mel hears a mysterious ringing in her room. She looks inside and she finds a transceiver, one similar to the one she had during her time in Aperture. GLaDOS must have sneaked it on when she was knocked out before escaping. GLaDOS is telling her to come back as she has something special to show her.
Mel manages to make her way back to the enrichment center which now has connection to the outside world and is now distributing to the humans, with GLaDOS being in control and there being absolutely no human employees. An elevator waits for Mel as she lowers back into the enrichment center. GLaDOS tells Mel that she wants her to help with testing. She has taken previous test chambers that Mel has gone through, including ones in the now-modernized test shafts from the Innovators Test Shafts, and GLaDOS has made them much more advanced and complicated, being more difficult to complete.
Mel makes her way into the old Chamber 03 in Test Track A. The chamber can be seen being renovated with panels in the walls budging back into place and some being replaced by brand new ones with better surfaces on them. When Mel gets to the exit in Test Chamber 08, GLaDOS lets her exit out of a panel in the elevator room as the elevator is broken here. She hops onto a catwalk and is put into a pneumatic diversity tube system making her way toward Test Track 05. However, if Mel were to wait in the elevator room in Test Chamber 08, it opens and Mel can go down it. GLaDOS questions why she does this and allows her to complete the rest of the Portal 1 test chambers, un-modernized.
If Mel went through the correct way or completes Test Chamber 19 in which she is sent through a new elevator room, she is put inside the first chamber through a cube dispenser, along with the cube. However, GLaDOS disables the cube dispenser and grabs the redirection cube. Some arms in the wall begin to edit it as GLaDOS makes the chamber more difficult. The cube is given back to Mel. Instead of a normal redirection cube, it is now a double discouragement redirection cube. This cube, when in the directory of a thermal discouragement beam, will split the beam into two and push it out the sides of the cube, out of Mel's way.
After completing Test Track 05, Mel is told to go into the actual elevator tube, without an elevator. She gets in and is sent upward, she is transported to Test Shaft 10, 'Lima Whiskey'. This shaft is almost completely modernized, and it, once again, introduces another new test element. This element is known as the portal redirection cube. When shot by a portal, the cube redirects the portal shot to whatever direction it's facing. Another element known as a Quantum Portal Tracking Wall is introduced, known as a Moveable Portal Wall, this is the only surface to allow portals to stay on it while it moves. Mel gets through the spheres and GLaDOS directs her toward the control room in the C Sector Maintenance Core. She hops in the vent elevator and is transported down to Test Track 6.
Test Track 6 is now more advanced featuring a mix of all the other elements introduced. In Test Chamber 22, GLaDOS shuts off the power and begins to move it closer to her, when it's complete, the exit doesn't go to an elevator room. But to a catwalk instead, directly toward GLaDOS' chamber. When inside GLaDOS gets Mel into an elevator down to the now brand new Test Shaft 02 of Aperture Science: Innovators. The chambers now feature the new double redirection cube and are more advanced.
After this Test Shaft, Mel makes her way to the very top of the Test Shaft and finds an entrance to the Enrichment Center, sealed off of course, but opened by her using the Portal Gun. She finds an elevator that is redirected by GLaDOS into Test Track 234. This more advanced Test Track features a brand new gel that GLaDOS had invented known as Adhesion Gel. It's a sticky gel that is basically the opposite of propulsion gel, anything covered in the gel that is put down will stick to walls, floors and ceilings and won't even be picked up by funnels. Mel walks slower through it and it can allow her to walk up walls if there's a curved surface covered in it. Also, if an uncovered object is placed on the gel then it would have the same effect as a covered object on a bare surface, it will still not be picked up by funnels. After the Test Track is complete, Mel is transported toward the makeshift chambers created by AEDAS in the CORE. They've obviously been altered by GLaDOS to meet her standards but nonetheless are test chambers that Mel can complete.
After all the CORE chambers are complete, GLaDOS transports Mel through her Central Core Chamber up to Test Shaft 12, 'Ingrid Prestige' which is undergoing modernization. Here, GLaDOS is testing Mel's skills. EVERY test element in the game, whether it be Pellets, Gels, Lasers, Funnels, Light Bridges or even Diversity Vents, she is using EVERYTHING she learnt to test her skills. After completing all the tests, GLaDOS once again thanks Mel and she officially hires Mel as the very first human staff member of the 'Aperture Science: Robotics, Engineering and Research Center'. Wheatley and Terry have been made her supervisors to help her do her job, like co-workers.
Mel, Wheatley and Terry, along with the guidance of GLaDOS, all work together to recreate the old co-operative test bots ATLAS and P-Body. Who are the protagonists of the co-op campaign of the game...