GLaDOS had transferred from her main body into an android one; something she didn't do often. But some things just couldn't be experienced properly without it. Viewing something with her optic using the many security cameras that Aperture Science was laced with was just not the same as physically standing in front of it.
She was sure that the craving for more physical experiences was all Caroline's fault. She'd never had any urge to be less mechanical until she became more aware of Caroline. But with Caroline's voice came memories. Good ones and bad ones. It was like experiencing the woman's life all over again. She remembered being a young human woman, and the thrill of getting a wonderful job as assistant to Cave Johnson. She remembered dedicating her life to science. She remembered falling for Cave.
It was less like remembering her own life and more like watching videos of someone else's life, which only made it worse. She could feel the memories of so many wonderful emotions, while knowing that she had never personally felt them and never would. But, despite never having known Cave, she fell for him through Caroline's memories the same way she would've if she'd truly been there.
Which made the bad memories worse. She could feel the same sadness that Caroline felt when she learned of Cave's illness, when she sat by his hospital bed, when he died. But that was all she could feel; sadness. She never had the chance to comfort him, or hold his hand, or any of the other priveleges that Caroline had once had.
And she could feel the terror, panic, and sorrow that went through Caroline right before GLaDOS was created. Being rational, GLaDOS knew it was for the best.
Without her, Aperture would've crumbled away to nothing. When it came to the big picture, becoming GLaDOS had been one of the greatest contributions Caroline had made to science. But another part of her didn't care. She loved science, she really did, but Caroline had wanted to die with Cave and GLaDOS could see why. Caroline had always loved Cave just slightly more than she had loved science. GLaDOS wasn't sure about herself.
She'd insist that the only thing she cared about was science, but she was beginning to doubt the truth in that statement. She should've been focused on testing. But instead, there she was; in an android body, with Aperture on auto pilot, sneaking off in the middle of the night to the ruins of 1970's Aperture. It was something she had been finding herself doing far too often lately.
Making her way through the remains of what was once Aperture, she eventually reached that familiar office. She remembered it from Caroline, and she remembered it from the other times that she had visited it recently. His office.
She didn't know why she kept torturing herself with visiting; the memories were always the clearest there. She didn't want to practically be able to feel his lips against hers, knowing that it never happened and never could happen. She didn't want to remember being called into his office for "important news" on one of the worst days of Caroline's life.
She had been the first to know about his illness. The first to know that her stupid, stubborn, boss had gone and bought moon rocks that he couldn't afford, ignored safety protocol, and ended up sick. It was all his fault. Maybe if he hadn't gotten sick, the plans to put his consciousness into a machine would've worked out. And surely he would've wanted Caroline by his side for eternity. Maybe then GLaDOS wouldn't have been left so alone.
She hated him for being so stubborn and so selfish. But he wasn't being selfish, not really. He hadn't done it for himself. He'd done it for science. Which only made GLaDOS love him more.
So she sat there, in his familiar office chair, staring up at the familiar painting of him and Caroline. She hated Caroline for that. Caroline had been there for most of his life, all the way until the end. GLaDOS, on the other hand, had never even met him. Not really, anyway. Only in Caroline's memories.
Sitting in his chair, looking up at that painting, and listening to his pre-recorded messages; that was as close as GLaDOS would ever be to him. And that hurt her more than anything she had ever experienced.
.