The facility was quiet; panels shifted among themselves, turrets clicked quietly, and Atlas and P-Body tested with each other. GLaDOS hung in her chamber, watching the two robots test.
It had been about a year since Chell had left. GLaDOS still hadn't completely coped with her newfound memories. She saw so much of her life before, and one person stood out the most…
"CAROLINE DELETED" the Announcer announced, breaking the silence. GLaDOS shook her core, trying to physically remove the weight of her new memories. She desperately longed to truly delete them, but it kept on resurfacing, as if there were millions of backups...
Deep in the shadows of Aperture Science, a lone figure moved. Not even GLaDOS realized that an experiment from long ago had survived and was now roaming the corridors. The shadow flitted about through the panels with such stealth and grace.
It was not the rat, for he usually kept to his dens. This shadow moved as if she carried a burden, and she did. She had seen so much in her long life, things she wished she could delete from her memories. But she knew that she mustn't, for it is experiences that make the person.
She had watched the test subject throughout her journeys, much like the rat had. The shadow admired her strength, her resolve, her determination. When the Central Core had let her go, the shadow had made a silent promise to give the truth to her.
So the shadow waited, waiting for the right moment to escape. It wasn't because she hadn't found a way, oh no. The shadow knew the facility like the back of her hand, maybe even more than GLaDOS herself.
No, the shadow was merely waiting for the right moment to go, waiting for the world outside to heal, waiting for the test subject to relax for a bit.
In a month's time, she would go out into the world for the first time and find the woman.
Then all would be revealed.