Oh. Well that's a pleasantly straightforward answer. More than she asked, even, the how in addition to the where. GLaDOS hums softly, scanning the sky as though she will be able to perceive evidence of this breach with these pathetic little eyes.

"Why does it do this?" she asks. "Is there a way back? Isn't anyone going to stop it? Also." She looks back at him, this apparently nonhuman entity, just like her. "Does it always force these - human appearances?"

She is asking many questions. Too many. Settle down, GLaDOS.

Or just GL, she supposes bitterly. No disc operating systems in this miserable little body.