The more she watched Chell test, the more GLaDOS realized how different she was from Lizbeth. For a start, Chell's eyes were more of a grey-blue than Lizbeth's brilliant sapphire ones, Chell also had tan skin, giving her a healthy glow in contrast to Lizbeth's porcelin skin, which made her seem frail, which couldn't have been further from the truth. But what stood out the most to GLaDOS was how she went about her tests. While Lizbeth had a feminine elegance, a constant smirk and a way with words, Chell was strong and silent, her face showing nothing but concentration. It was respectable, in a way.

"Too bad I'll have to kill her at the end." GLaDOS muttered to herself. Chell was extremely good at testing, she cleared one after another without taking a break, but GLaDOS could tell that Chell's energy was fuelled with hatred towards the AI, a hatred that increased with every new obstacle. Finally, Chell exited the final chamber and began the ride to her doom. Only five more seconds until she's escorted from the Being Alive Club, GLaDOS thought. 5, 4, 3, 2, wait... What?

"What are you doing?" GLaDOS asked the test subject. The girl had somehow managed to keep a calm mind and escape the trap without being baked and did not reply as she began her newest, unplanned and most dangerous test of all, and it wasn't long until GLaDOS lost sight of her. That didn't mean she'd lost her, no, GLaDOS knew exactly where Chell was headed, and it meant that she might be expecting a visitor in a little while. She already had traps along the way, as a couple of test subjects had escaped in the past. The traps usually took care of them, as only one had ever made it to GLaDOS' chamber. It was a remarkable feat, and GLaDOS was still impressed by it five seconds later as she was scraping his remains off of her chamber wall.

Just over half an hour later, to GLaDOS' surprise, Chell had managed to bypass all of the traps and was making her way down the corridor towards GLaDOS' room. GLaDOS turned to face the door in anticipation as Chell's footsteps became steadily more audible until the door opened with a hiss.

"Well you found me. Congratulations." GLaDOS sarcastically remarked to Chell. A difference between Lizbeth and Chell was drawn right there, as Chell approached the supercomputer without speaking a word, whereas Lizbeth would have made a sarcastic remark at this point. GLaDOS had gone past admiring the test subject's guts, and decided she'd settle with neurotoxin instead. As she was counting down to the Chell's 'surprise', she got a surprise herself as something dropped from her. Chell went over to the object and picked it up. GLaDOS recognised it from somewhere, but it wasn't until the object met it's fiery doom that she realized what exactly it was. It was her morality core. It was sort of GLaDOS' conscience, but all it did was fill GLaDOS' mind with kind thoughts that she promptly ignored. It was a shame, there was one scientist who told the others that the conscience could always be ignored, they didn't listen to him, and he was the only one smart enough to survive. Now it was gone though, she could kill this girl without a little voice holding her back.

GLaDOS figured that Chell was most likely one of the captured children from the first, and last, annual 'Bring Your Daughter to Work Day', as GLaDOS found they could stand being in a room filled with neurotoxin for a while longer than other test subjects, and this girl was holding up pretty well. She was fighting a losing battle though, because even though she seemed capable of surviving, the neurotoxin would kill her before long. There was no way she was leaving this room ali- GLaDOS' thoughts were cut short with a bang as a bullet collided with her, knocking another core off of her. Chell picked up the core and tossed it into the incinerator, leaving GLaDOS without her curiosity, replacing it with the burning desire to murder the lunatic. Two more bullets flew her way, but GLaDOS managed to swing enough to dodge them. However, the third one hit home and knocked another core off. GLaDOS didn't feel much difference this time, but the space that the core had inhabited was overtaken by anger once more, leaving GLaDOS feeling nothing but white hot rage towards this human, the human who reminded her of her friend, the human she needed to kill. Chell's determination grew with GLaDOS' anger so she could continue to dodge her relentless attacks. There was another bang as the third core detatched from the supercomputer. All at once, GLaDOS' anger disappeared, leaving her feeling... Nothing. GLaDOS felt her system go crazy as it tried to make up for the important data that was lost, but all it suceeded in doing was overheating and breaking GLaDOS even more as her fans attempted to keep up. Soon, her fans were moving so fast they created a vaccum that pulled GLaDOS, Chell and the rest of the room up through the ceiling with a crash. That was when everything went black.

GLaDOS was forced to watch her defeat over and over, Chell's determined face now permanently etched into her memory, just as Aria's tears and Lizbeth's smirk were. How long had passed, she didn't know, maybe days, maybe years. Maybe Chell had gotten out somehow and was sending her children off to school, maybe Lizbeth was sat telling her grandchildren about her adventure in Aperture Science, GLaDOS had no way of knowing. That's strange, she thought, the video's stopped. GLaDOS was confused as the black returned. Gradually, she felt her system coming back online. Finally, she regained movement and sight. She pulled herself up from the floor and looked around. The first thing she noticed was that the facility was in complete ruin. The second thing she noticed was her murderer stood before her.

A/N: Hey! Sorry for my accidental break from writing and that this chapter feels rushed, I've been stuck for ideas. I didn't want big points of the story to happen in consecutive chapters, but it turned out like that, so I hope it's okay!

Thanks to Emily Tristan, likekattheboss and lulubot3000 for reviewing!

Also thanks to CheezyPortalFan, and yes, it is a prequel, sorry if it was a bit vague, but it means I get to write Wheatley, and that I am excited for!

~Duckie