[A/N: No pairings in this one!]

"I hope you realize how unlikely it is that you are going to complete this challenge."

Startled by the sound of GLaDOS's voice, Chell jerked her head up and looked around. She was in a small one-room apartment, all she could afford with her piddling waitress salary, sitting at a rotting wooden desk in a thankfully not rotting wooden chair. A threadbare bed sat in the far corner. But there was no one there, least of all GLaDOS.

She'd heard the AI's voice before. Ever since she'd been released from Aperture, it had been there, chiming in irritating comments in all her moments of self-doubt and depreciation. But lately, it seemed like she was hearing it more and more.

"Stop it," she muttered, aware she was talking to herself. "You're not even here."

"Of course I am," GLaDOS replied. Rather than emanate from one specific location, her voice seemed to come from everywhere, as did the dark chuckle she let out at that remark. "I am always here. Never forget that."

"Stop it," Chell ordered again, her voice stronger and louder this time. "You're not here. You're back in Aperture where I left you."

There was another chuckle, then, "You may believe that all you wish, [Subject Name Here]. However, your belief will not change simple facts. Such as the simple fact that I am always here. Always."

Chell pressed her hands over her ears, the not-so-fictional biography she'd been working on for National Novel Writing Month forgotten. "Leave me alone." She'd never had a conversation with GLaDOS before; in the past the voice had always left her alone right after it made its remark.

"No," the AI—no, not the AI, just the voice—said flatly. "I will not." And it was just as loud as if Chell had never covered her ears, which made her more determined than ever to stick by her belief that it was all in her head.

Somehow, that belief did not make her feel any better.

"Why not?" Chell demanded against her better judgment. After all, knowing Aperture technology, it was more than possible that GLaDOS had the ability to do this, whatever it is this was. "Why—no, how are you doing this?"

"Because I enjoy it," the voice responded, all the sardonic lilt that had always been there instantly returned. "The inside of your head has always been an interesting place. As well as an insane one. Because you are insane. You do realize that, don't you? And as for how I am doing this, well, there are three very simple answers: The first is that it is none of your concern. The second is that I highly doubt you possess the mental capacity required to comprehend it. And the third is Science, of course."

"I'm not insane," Chell said on instinct, although at the current moment, she wasn't sure. "And if I am, it's because you made me that way."

There was a surprised snort. "I beg your pardon?"

"No, you did," the human insisted, her voice growing steadier as she went on. This was familiar territory to her, arguing with a homicidal supercomputer that probably wanted her dead. It felt normal. Natural, even. "You tried to kill me, dragged me back in when I was out, and then tried to kill me a few more times before you finally let me go. You're sending me mixed signals. If one of us is crazy, it isn't me."

"As if," GLaDOS snorted. "Might I remind you that I am the most massive collection of wisdom that's ever existed? It's not possible for me to be insane. And if it were, I would know about it."

"Then why won't you leave me alone?" Chell demanded through gritted teeth. "You don't need me. You let me go three months ago. Find someone else to torment."

There was silence, and then, "There is no one else."

"What?" the human asked, not sure she'd heard right. "What do you mean?"

"I mean that there is no one else," GLaDOS repeated, sounding reluctant to admit it. "Everyone else is dead. There is only you. In case you've forgotten, the moron managed to turn every single test subject I had in stasis into vegetables. I blame you for that, by the way. Why couldn't you have turned into a vegetable as well? Then my life would be significantly easier. The moron could have found someone else to attempt to escape with, and after he woke me up, I would have been able to dispose of them both."

Chell could practically feel the AI glaring at her, and it made her head spin. Despite the fact that it wasn't doing any good, she pressed her hands harder against her ears. It made her feel better. "I don't care. Stop it. Get out of my head or I swear to god I'll find my way back to your facility and make you stop it."

"Oh, of course you will," GLaDOS (by this point, Chell couldn't believe it was anyone but the supercomputer herself) mocked. "You're far too weak and obese to come looking for me, not to mention far too stupid. You probably can't even find your way back here. So I suppose you'll just have to get used to me. Now that my technology has adapted to your…unusual…brain, there is nothing stopping me from communicating with you every minute of every hour of every day for the rest of your pathetic little life."

Chell was about to bite back with a furious response, but then something clicked and realization spread across her face. "You're trying to goad me back. Why?"

For once, the AI was silent.

"Tell me," Chell pressed.

The silence continued for a few moments more, then GLaDOS sighed. "I require your assistance. Well, anyone's assistance, really. But as you are the last remaining human I can communicate with, you are the one I have chosen to assist me. Congratulations." And Chell could have sworn she heard a party horn.

"What makes you think I will?" she asked. "You haven't even told me why you need my help yet."

"All you need to know is that I would not be speaking to you if it were not absolutely necessary," the AI replied, dodging the truth with practiced skill. "And as for why you will, well, I suppose it is possible that you would rather be driven slowly insane—that is to say, more insane—than help me. All I did was save your life and release you back into the human race out of the goodness of my heart, after all. Even after you broke my heart and killed me twice. Remember, I did absolutely nothing to provoke either of your heartless attacks on my life. You're just a horrible person. And your test results prove it."

Chell had a bad feeling that GLaDOS was going to keep talking forever unless she said something. And it wasn't that she wanted to help the AI, but she didn't think the computer would be kind enough to even let her sleep. Aperture had nearly been enough to drive her insane. Aperture inside her head would be enough to drive her insane.

"Fine," she said abruptly, cutting GLaDOS off from the tangent she'd been going off on. "I'll do it."

"Excellent," the AI said, not sounding surprised in the slightest. "I knew you wouldn't want to miss the chance to make up for all of your past wrongdoings."

Chell clenched her fist by her side, biting back her temper. "Just promise me that after I've helped you, you'll let me go."

"Oh, of course," GLaDOS said, her voice oozing with false sincerity. "Why would I want to keep you here with me? I only want you gone, you know. Well, actually, what I want is your assistance. But after you've provided it, I'll only want you gone again. Don't worry, [Subject Name Here]. You have nothing to fear from me."

The AI's voice was dripping with sweetness so false a child could have seen through it, but Chell didn't want to find out how fast having the computer's voice constantly inside her head would drive her crazy. "And you have to remove the…whatever you're using to talk to me. I want it gone. Okay?"

There was a long, suffering sigh. "I suppose that would be acceptable. However, I will require your phone number."

Chell made an internal promise to have it changed shortly after. "Fine."

"Good," GLaDOS said. "Now that we understand each other, you will leave immediately. I trust you remember the way?"

Chell nodded, then remembered the AI couldn't see her and said, "Yes." And she did. Every time she left work, she passed right by the wheat field, and sometimes she glanced into it, seeing if she could catch a glimpse of the rickety wooden shed. She'd never managed to.

"Good," GLaDOS said again. "And don't worry. If you lose your way, I'll be right here."

"Like a GPS," Chell said as she stood up. It wasn't really meant to be an insult, but the AI bristled anyway.

"I am not a GPS. Do not compare me to your vastly inferior pieces of 'technology.' Unless, of course, you wish for me to rescind my generous offer of letting you go."

Chell paused at the door. "Don't threaten me, unless you want me to rescind my generous offer of helping you."

It was an empty threat, given how the AI was inside her head and all, but there was a pause, and then, "Of course. My…apologies."

GLaDOS's apology sounded just as insincere as her promises, but the fact that it had been offered at all made Chell's brain kick into automatic panic mode. She struggled to keep her breathing steady as she grabbed her car keys from the bowl by the apartment door.

"Is there something wrong?" GLaDOS asked. "It's not that I'm concerned. But if you are going to have a heart attack, it would be good to have some warning so that I know to prepare you a place in the morgue."

The fact that Aperture had a morgue didn't surprise Chell in the slightest. "I'm fine," she said as she headed out the door and started down the hallway. "I'm leaving now."

"I know," the AI's dry voice said. "I can see."

That made Chell want to shut her eyes on instinct, but instead she forced herself to keep them open, swallowing hard and licking her suddenly dry lips. "You can…you can see?"

"This implant would be next to useless if I could not tell what was going on around you," GLaDOS said. "It is tapped into all the critical functions of your brain. Eyesight…hearing…pain…"

She placed all her emphasis on the last word, lowering her voice threateningly, and Chell felt fear surge through her. With turrets, she could shove them over. With neurotoxin, she could hold her breath. And with the AI herself, she could pull things off of her and throw them into an incinerator.

But how the hell was she supposed to fight something she couldn't see?

The elevator doors opened with a ding, and Chell gasped, jumping back. She didn't remember pressing the button, but there was no one inside, so she supposed she must have. Cautiously, she stepped in, and rode it all the way down without any objections from GLaDOS. The AI must have felt that her earlier threat would suffice for a while.

However, when Chell reached her car in the outside parking lot, she heard a snort of derision and stopped. "What?"

"That thing belongs to you?" GLaDOS asked.

"She's not a 'thing,'" Chell said, bristling. "Her name is Baby."

At that, the AI actually let out a laugh. "You named your car Baby? How pathetic. Are you really so desperate for companionship that you would give such a term of endearment to a non-sentient object?"

Opening the door, Chell slid in and started the engine. There was only one response to that.

"The cube's name is Sweetheart."

In retrospect, she supposed she should have expected to be mocked for that one.

It wasn't too long of a drive to Aperture, but Chell was about ready to pull her hair out by the time she arrived. The AI had nothing but negative things to say about her driving. It was like Driver's Ed all over again.

"All right," she snapped as she shifted the car into Park and pulled her keys out. "I'm here. You can see I'm here. So stop!"

"Stop what?" GLaDOS asked. "I was merely explaining to you that the proper way to drive through a field of wheat is not at sixty miles per hour. This is not the interstate and your driving skills are subpar at best. You could have hit my shed, and then you would have been spending the next three days repairing it."

Chell peered through the windshield at said shed, which rested about ten feet in front of her. It was closed. "Yeah, but I didn't. Are you going to open the door?"

"Not until you get out of the car," the AI replied. "I do not wish to have it open any longer than necessary. Is that understood?"

Chell didn't care enough to ask why. She nodded, even though GLaDOS couldn't see her, and stepped out of the car into the crisp autumn air. The shed remained closed as she walked up to it; after a moment, she put a hesitant fist up and knocked.

"What do you want?"

It was GLaDOS, sounding as bitter as ever, but instead of emanating from all around this time, her voice was coming from one specific place, an intercom above the door.

"What do I want?" Chell asked blankly.

"Yes," the AI repeated. "I trust you understand basic English, since you seem to have acquired speech during the time you haven't been here."

"But you—but you asked me to come," Chell protested, despite the cold feeling of dread that was beginning to knot her stomach. "There's an implant in my head, and you've been using it but now you're using it more because you got it to work—" She let her voice trail off as she stared at the intercom expectantly.

There was silence, and then, "I have not initiated any contact with you since you last left the Enrichment Center three years ago."