(Sorry, I've had my obligatory winter flu, during which my brain turns into a potato. Anyway, new chapter, but this one is more of a 'novelization' of the flashback scene from Lab Rat - Don't worry, this will be the only one.)

Tenacity

Doug crawled through the air duct, his shoulders throbbing. The GLaDOS' voice echoed around him, coming at him from every angle.

"…A new employee initiative of forced voluntary participation…"

He tried to take his mind off her words by planning his next move.

"…Please remember, science rhymes with compliance. Do you know what doesn't rhyme with compliance? Neurotoxin."

A drop of sweat ran across his lips, the salty tang filling his dry mouth.

"… Assures you this is a strictly selfish impulse on your part, and why can't you love science like [insert co-worker's name here]?"

The duct opened out into a more spacious area, large enough for Doug to stand up. He paused to stretch his arms and look around, relief momentarily spreading through him as he realized where he was. The blueprints had provided a detailed map of these vents, and as far as he could remember, he was on the right track to reach the offices.

The GLaDOS spoke again. Her voice was fainter now, but that did little to detract from the sting in her words.

"And now there's just you. All the others are dead. You've evaded capture for weeks. What makes you so different?"

Weeks? He knew it had been a good few days since the encounter with the escort robot; he had decided to stay away from the Vault for a while until he was sure the mechanical behemoth wouldn't follow him. But surely it couldn't have been weeks.

His heart thudded against his rib-cage, images of Chell's lifeless body rushing through his mind. He began moving forward slowly as the GLaDOS' words and all that they entailed registered in his brain. The computer must have found Tremblay and the others while he had been out trying to draw attention away from them. There was no reason to go back to the empty office by the fan; no longer anyone to provide for, no one with whom to discuss escape plans. Aperture started to feel much, much bigger.

For a second, he toyed with the idea of trying to reason with her, possibly ask her how she would cope with the itch should all of her subjects die. Access the Vault? And what if she couldn't? He had just opened his mouth to put the thought forward when she spoke.

"Ah… Delusions of persecution, pathological paranoia; it's all right here in your file. Have you refilled your prescription lately? Schizophrenia is a culturally bound phenomenon. Its pattern of expression is filtered through the cultural substrate in which its symptoms develop."

Doug continued to move forward, no longer with any goal in mind. He tried to reassure himself by thinking of the jar of ziaprazidone tablets in the companion cube. An entire jar, practically brimming with the medicine; they would last until he found a way to escape. All he had to do was think of them, refuse to let her play with his thoughts.

"In technological societies, this manifests as delusions of surveillance and a belief that advanced technology is deployed against you, usually with some vague unseen 'other' out to get you."

"You're not vague," he said, raising his voice to ensure she heard him. "You're pretty damn specific."

"If you continue to selfishly evade me, it' not going to reflect well in your file."

"Of course, the files!" said Doug, smacking his forehead as the idea came to him. He dropped down into a lower section of the labyrinthine ducts and headed towards the offices, running with every last ounce of his strength. His shoes clattered against the thin aluminum, but he no longer cared about keeping quiet.

"Is it just a coincidence that you've been diagnosed with schizophrenia and now believe a homicidal computer is out to get you?"

Reaching a vent that led into one of the offices, he pulled it open and leapt down into the room, adrenaline coursing through him.

A line of filing cabinets lay in the corner of the room. Yanking the draw open he started flicking through the files within, moving so swiftly that within a few seconds his fingers were covered in paper cuts. She was still talking to him, but now he only noticed snatches of her sentences.

He pulled a file out and started reading, gripping the paper so tightly that it almost ripped. He was faintly aware of GLaDOS talking about cats, and in a corner of his mind, he remembered that all employees with felines had been asked to bring their pet in for the computers activation. It was to be her very first experiment, a test related to the Schrodinger's cat theory.

It had come about just after they had installed Wheatley, under the guise of the Morality core. GLaDOS had convinced Tremblay that the new conscience had eradicated all her murderous urges and politely requested access to the neurotoxin in order to attempt the experiment.

He had, of course, allowed it.

"The bad news is reality doesn't exist. The good news is we have a new cat graveyard."

Obviously she had gone ahead with the test anyway. She must have been doing something to combat the itch. That no longer mattered, though. He had found the file he needed.

"Yes, this is the one."

One of the computers was still turned on, and, after removing a dead body draped against the chair, he sat down in front of it. Holding the file with his teeth, he brought up the testing list and typed in the subject's code. The machine was agonizingly slow, and Doug had almost given up when the list of testing candidates appeared. It highlighted the subject he had requested information on, and displayed their position in the chart.

Chell [Redacted], placed in the one-thousand, four hundred and ninety-eighth spot, just four up from the bottom. It was her.

For a second Doug paused, unsure of whether to go through with his plan. The fact that she was still registered meant there was a chance she was alive – it was unlikely that GLaDOS would needlessly kill a perfectly healthy subject – and in her current position, it would be years before the machine got round to testing her. For the moment, she would be safe. During the last few days, finding her and subsequently protecting her from harm had been one of his primary concerns; he only wished he had the willpower to follow through with that now.

He opened the file again; the GLaDOS' words were now a simple buzz in the background.

There, in the corner of the page, was the note that had caught his eye all those months ago when Tremblay had passed the file around.

'Test subject is abnormally stubborn. She never gives up. Ever.'

It was just as Wheatley had told him; the laboratory had considered her too tenacious to test safely. Although his work on the human experiments had been brief, Doug knew that this was a rare occurrence. It was exactly what he needed; the person he placed in GLaDOS' firing line would need to have much more then just brainpower and physical strength. His own actions were enough to show him that he didn't contain such a force.

He bit his lip, hands hovering over the keyboard. He could still remember Caroline pleading with him to keep Chell away from the facility, a request he had let slide. Now the girl was going to have to pay for his carelessness.

He knew it was ridiculous to entrust such a task to a sixteen year old, and yet he felt compelled to move her to the top, as if something inside him was trying to move him along. The word tenacity spun around his mind.

With unsteady hands, Doug placed Chell's name in the number one spot and confirmed the modification, closing his eyes as the computer saved the new testing order.

"Sorry, Caroline."