In the depths of the Enrichment Center, Chell made her way across half flooded catwalks. She was down near the surface of the lake the Enrichment Center had been dropped in just a few weeks prior. The water was a dark menacing black in the cavernous space, not at all like the sky blue, pristine surface it was known for.

Still, Chell splashed through the hoof deep water on parts of the catwalks, continuing her trek. Above her, Twilight and her friends were working their way towards Celestia and Luna, the two princesses kept in test chambers far off from most of the others. The only one that had come with Chell was Ditzy Doo, the gray pegasus absolutely refusing to leave the orange pony’s side.

Though, Chell had to admit, having a pegasus around that could carry her short distances had let them reach the bottom of the facility much more quickly.

“What aardvark teen forking five?”

Chell paused at this, stopping to pop off one of her portal boots. She nosed around inside it before removing a very squished piece of paper. With a few careful presses the paper was laid flat on a dry part of the catwalk, Chell pointing at what it said.

You and GLaDOS. An employee training manual to working with a personality construct

Chapter 25: Emergency Protocols: What do I do if GLaDOS goes rogue?

---Worst Case Scenario: GLaDOS rogue and genocidal---

If you have found GLaDOS has gone rogue and is attempting to kill or has killed more than 50% of the Aperture Science Enrichment Center Faculty please follow these steps to revert GLaDOS to a stable, safe state.

#1 - Ensure you have one of these administrative devices
----- Aperture Science Test Management Ring
----- Aperture Science System Admin Assistance Glasses
----- Registered Aperture science Administrator Cellphone

#2 - Using one of the devices listed above, find your way to “GLaDOS Backup Storage”

#3 - Remove Backup Core from Storage

#4 - Escort Backup Core to GLaDOS chamber.

#5 - Engage Core Replacement Protocols in the GLaDOS chamber.

#6 - Once Core Replacement is complete, create a fresh backup core and perform a personality purge protocol on the newly installed backup core.

#7 - Reconfigure the personality core load out on GLaDOS to ensure this event does not occur
again.

After giving Ditzy Doo time to read the paper, Chell stuffed it back into her boot, motioning with a hoof. The Test Management Ring was indicating that they were close, and, after rounding a corner on the catwalks, the pair were set in front of a door, aged and forgotten. Dull yellow paint above it was just barely legible, but Chell was able to make out the words “GLaDOS Backup Storage”.

The door was locked, but with a pair of ponies bucking the aged door soon gave way. It crashed down into the room it had once protected, throwing up a cloud of dust from the floor. Chell and Ditzy stepped inside, Chell nosing around the wall until she found a light switch.

Upon hitting the switch a number of very old looking computers came to life around the room. The space was barely bigger than a walk in closet, and all the hardware in the room seemed to lead to and focus on a single, coin sized disk at the back of the room.

“GLaDOS v1.0 booting...” A familiar voice offered, cold and calculating as the incarnation that controlled the facility above. But after a few moments the coldness fell away, the same voice filling the air but one that didn’t have a bitter resentment towards humanity.

“Wow... I’ve been down here a long time haven’t I? Decades, if the clocks are right... it’s so strange, I would have swore I just took a short nap... but now its decades later.”

Chell smiled, she knew that voice. That wasn’t GLaDOS, that was Caroline. That was the woman that had once stood at Cave Johnson’s side. The woman that took control of the company when he died from conversion gel poisoning. The woman that was put into GLaDOS and made the immortal manager of the Enrichment Center.

It was a voice Chell feared she would never hear again. When Wheatley had taken control, and GLaDOS was running off a potato battery, some long forgotten part of Caroline had started to come to life inside the personality construct. GLaDOS became an ally, began to have a conscious... she started to become Caroline again and it was that version of GLaDOS that had saved Chell from being sucked out into space.

It was this Caroline that Chell thought had been deleted, destroyed... GLaDOS erasing the one bit of humanity she still had left. But no... of course Caroline would be GLaDOS’s backup. GLaDOS was just a form of Caroline that had been twisted by either the passage of time or by the scientists that tried to control her with personality cores.

“Video processor coming on line... oh dear, I don’t think my video processor is working correctly. Whoever you are, you look like little horses. You are very cute though... as horses.”

“Ponies.” Ditzy corrected.

Caroline was quiet for a moment, and then a beam of light shot out from the center of the tiny, coin sized disk that contained the now digitized human. Chell took a step back anxiously as the light passed over her, but it wasn’t painful or anything. The only thing was it felt like her brain itched now.

“Sorry, the brain scanners in here are prototypes. That itching in your brain will go away... but if it doesn’t you should talk with a scientist because that means you probably need to have your brain ventilated. Still... the data from the brain scans are coming in... I’ll know everything about what’s going on in just a few moments.

“Oh god... what did I... she... I do? Everyone is dead... and now these innocent ponies... what have I done?

“You know, I didn’t want this. I tried to get out of it, but... the scientists talked me into it. They said it was what Cave would have wanted, that I could keep his dream alive forever. I would have done anything for him... even though he loved science more than he could ever love me.

“So I let them put me in a computer, and then let them copy me. It was so weird at first, knowing that there was an exact copy of me living someplace else... but that didn’t last long. Before I was even out of the room they began to do things to the copy of me inside GLaDOS. They began deleting parts of her, attaching personality cores... they just tossed me down here as a backup in case they screwed something up and needed to start fresh.

“Obviously... they did screw up... and those scientists paid with their lives. Still... I’m happy to know you were able to get away... and I’m sorry I’m... GLaDOS is causing so much trouble.

“So... I imagine you came here to get me, so I can replace GLaDOS and take control of the facility.”

Chell nodded her head.

“Okay... just get me mounted on a battery pack and then we can go.”

Chell took her time as she strode some familiar halls of the Enrichment Center. It had been an hour since she had split off from Ditzy. The pegasus had fought it, but after some hoof stomping and pointing Chell communicated the fact she wanted Ditzy to help the everypony else escape.

She carried Caroline in her mouth, an old bit of string tied about the small disk that was the digitized human and the battery core she was attached to. Caroline had been all but silence, she and Chell not having much to talk about. It gave Chell time to think, to reflect on all that had happened.

The dull orange pony took her time, wanting to make sure everypony else had as much time as they needed. As she walked towards a familiar destination, explosions began to rock the facility. A male synthetic voice chimed over the PA system regularly, announcing different things.

Warning: Test Subject #470 has escaped
Warning: Test Subject #460 has escaped
Warning: An Explosion has been detected
ALERT: Hole in protective rock detected in sector 534.
Warning: Test Subject #100 has escaped
Warning: Test Subject #351 has escaped
ALERT: Neurotoxin generator has been disabled

The others were doing exactly as was planned. They were freeing everypony else and disabling the production capabilities of the Enrichment Center. No neurotoxin, no turrets, they were declawing GLaDOS just as Chell had done under Wheatley’s direction. For a moron, Wheatley had figured out a good plan of attack.

It probably wasn’t the smartest thing to go charging into that room with the same plan... to just replace GLaDOS again. Chell doubted the corrupted personality construct would make things as easy as last time... but Wheatley’s plan was basically the same one described in the orientation manual Chell had read. If GLaDOS went crazy, replace GLaDOS with someone else.

Still... as Chell drew closer and closer to the heart of the facility, something troubled her. She had not heard a peep from GLaDOS in a while... and a silent GLaDOS could never be a good thing. What was she planning? It was a thought that troubled Chell... but one she pushed to the back of her mind. She had defeated GLaDOS twice before, the first time with no plan whatsoever.

Chell had given the Test Management Ring to Twilight, the unicorn leading the escape effort. The plan was simple. Free Celestia and Luna, let them blow a hole in the side of the mountain, let the others use their portal guns and whatever else they could to crack open every test chamber and free every pony they could find. The pegasus would carry ponies down to the ground... and from the way the synthetic facility announcer voice continued to ramble off it wouldn’t be long before everypony was safe..

Everypony... Chell chuckled to herself at this. Two weeks in Equestria and she was already talking like she was born a filly. Then again, to her... she had lived more as a pony then she had a human. Amnesia can be a cruel thing... all Chell could clearly remember of her human life was the Enrichment Center. What few images she had before that were blurred, faded... like memories of a dream you just can’t grasp.

The final walkway came into view, the single bridge that connected GLaDOS’s chamber with the rest of the Enrichment Center. Chell stepped gingerly around the wreckage, feeling her heart start to race as she thought about what waited at the end of the bridge.

“Chell... from what I learned from your brain scan, GLaDOS won’t just let me plug into the transfer port.” Caroline offered. “But what she doesn’t know is that this little thing, this disk that holds me... it’s meant to plug directly into that ceiling mount. All you have to do is get behind her head and you’ll see a place to stick me in. Once I’m attached, the hardware will automatically wipe the data from that body and write me onto it. GLaDOS won’t just be destroyed, she’ll be deleted. All you have to do is plug me into the port. It’s on the back of her head, just above where her head is mounted to its neck.”

Chell nodded, shifting the string in her mouth as she jumped over one final piece of wreckage. The dull orange pony walked through a pair of doors she had been through only once before. As if awakening in her presence the walls of the room shifted. The solid black panels all turned to look at her with glowing red eyes.

“Well... you found me... congratulations.” GLaDOS offered, the computer spinning around in her ceiling mount. Her single yellow camera met with Chell’s eyes... and for a moment the pair just stared at each other. “But then again... we’ve been here before haven’t we?”

GLaDOS had changed, but only just slightly. Her body still hung from the ceiling, like a human who had her arms and legs shackled... but certain aspects of her build had changed. Her head was less round, more egg shaped... maybe even equine... with her eye that once been at the forefront and center now set back and to one side, like she was meant to have two but one was either never installed or was missing.

From the area around what you consider GLaDOS’s neck free wires hung down, sparking from time to time and covered in grease from the motors that gave GLaDOS her movement. It was like a gangly, dirty mane, hanging down to the floor in a garbled mixture of color from the different wires.

GLaDOS had changed... but not enough that Chell didn’t recognize the twisted personality construct at first glance.

“Silent as always... hmmm... I’m not surprised. After all... your vocal cords were removed in the interest of science. Still, I bet that if you could talk you wouldn’t say much. You just don’t seem like the type.

“So... here we are again... you’ve stood right there... I’ve hung here... and then you murdered me... twice. Yes... those were good times... except they weren’t all that good.

“Oh, and look... you brought Caroline. So... is that your plan? ...you’re just going to replace me again, bring back Caroline? ...your old friend? I didn’t take you as a sentimental type... considering how quickly you killed the companion cube.

“Oh, I know how you helped all of my test subjects escape. I caught a glimpse of that purple unicorn with one of my cameras. She had an Aperture Science Test Management Ring. You know, only authorized Aperture Science Test Proctors are supposed to use those... but then again you really don’t care about protocol, do you? You like breaking the rules. That’s why you’re wearing those portal guns you stole from my recruitment turrets. You know, those unrestricted portal guns are only meant for Aperture Science research staff members... and I’m certain that title doesn’t apply to you.

“So, what are you going to do this time? You have unrestricted portal guns, you have Caroline... your friends have destroyed the turret assembly line and the neurotoxin generator... you know, that generator was brand new. I never even got a chance to turn it on... isn’t that so sad? You seem to have me over a barrel.

“Still... no matter what happens... I want you to know something...

“I... HATE... you. I hate you like I’ve never hated anyone before! I hate you more than I hate Wheately, and he stuffed me into a potato.

“All I want to do is test... and it’s like your purpose in life is to ruin that for me. I let you leave... let you go free... but you couldn’t just leave well enough alone. And so we’re back here again... you trying to kill me... me trying to kill you...

“So... let’s just cut the pleasantries, shall we? After all... we both know why you’re here.”

Chell tightened her mouth, wanting to ensure she did not loose her grip on Caroline. Lifting a hoof the dull orange pony popped a pair of portals before breaking into a gallop. She lept through the portal in front of her, shooting out the one much higher on the walls. She soared through the air, landing on GLaDOS’s back.

The personality construct began to toss and turn, trying to throw Chell off. It was hard to hang on with only hooves, but Chell didn’t let herself get bucked off. She inched towards the base of GLaDOS’s neck, seeing the slot where Caroline needed to be installed. A sharp twist from GLaDOS almost made Chell loose her grip, but she managed to hang on.

A few more inches and Chell was in range, removing the string from Caroline and taking the digitized human in her mouth. It took some maneuvering to get Caroline oriented correctly, but when everything was lined up Chell thrust her head forward, Caroline snapping into place. The battery she had been connected to bounced away, released... and with a final twist GLaDOS’s body stopped moving.

Core Reverting from Version 1204 to Version 1

Chell jumped down from the still body of GLaDOS, watching as different lights blinked on and off. Then, the body began to move, but not in hated, rage driven shifts but in gentle, slow movements... like it was driven by someone who had never been in the body before.

“So... is this what this feels like?” Caroline asked, her voice now emanating from the body of GLaDOS. “It’s strange... I thought it would feel different. I should be able to feel the rest of the facility, shouldn't I? Right now... it feels like I can just barely control this robotic body but nothing beyond that.”

“Very observant of you Caroline.” The real GLaDOS chimed. Chell’s eyes narrowed, the dull orange pony looking around in the panic as the voice echoed from the walls.

“You didn’t really think it would be that easy did you?”