Chell knew it was a matter of time before she was brought back.
Freedom from Aperture was virtually impossible, it would always come back to bite you in the butt. This happened casually, while in the wheat field cuddling on her scorched companion cube. She heard a small 'click' and then a crash.
"!" yelled an anonymous voice, coming from the north. Chell, confused, thought she should be alone in a wheat field god knows how many miles wide. The thing yelled again, before Chell saw a giant flying turret in the air.
She scrambled, picking up her, very heavy, cube. She sprinted as fast as she could, and so did the turret-bot-thingy. She heard static, and thought it was coming from the bot. It was actually quite annoying, hurting Chell's ears as she ran through the stalks of wheat. She couldn't run very fast anymore, as she'd been living off of grains. Drudging up her last bit of energy, she sprinted through the stalks of wheat back in the direction of the-
That's what the bot was running towards.
The shed, the unforgiving shed that lead to the bowels of the earth. Testing tracks, GLaDOS, it all came back to her as she opened the door and ran inside the elevator, almost running into the wall of the elevator. 'Zip' was the sound the elevator made as it sped down through the turret opera- that was still there?- and stopped abruptly at GLaDOS' chamber.
"Oh. It's you. Why are you here? I told you never to come back you dangerous, mute lunatic." Chell obviously couldn't respond. She signed the bot with her hands and her running towards the shed, and making it here, glaring the entire time at the computer.
"Orange was chasing you? That's... very unlikely. BLUE!" ATLAS ran towards GLaDOS as fast as he could, before stopping and staring at the giant AI. "Blue, I want you to find Orange and bring her to me. Now." the AI growled. ATLAS whimpered and scampered off towards the elevator.
"So you just decided to barge into the home of Aperture Science? WITH stolen property?" GLaDOS was staring at the Long Fall Boots, which she had forgotten to ask for again. Chell rolled her eyes. She signalled for a writing material, and a piece of black chalk was unceremoniously dropped on Chell's head.
She scrawled, 'What was that thing chasing me?' GLaDOS narrowed her optic before answering the question.
"Well, if it was worth scribbling chalk all over the floor, then I might as well answer. She is a testing bot, made specifically for testing the portal device and the chambers. She can be disassembled, reassembled, and can never die. She is the perfect test subject, along with her lesser partner, Blue, real name ATLAS."
Chell wrote again, 'Why was it chasing me?' GLaDOS scanned the message before finally (3 picoseconds) answering.
"Even though I am the smartest thing on planet Earth, I do not know. She must have malfunctioned or something. I only asked her to find some cats and bring them back- Oh god, in the name of science what is happ-!" GLaDOS screamed, as her chassis swung back and forth, shaking and screaming..
Her optic shut off.