[Chell watches GLaDOS closely, she's curious as to what she's doing. Was she going to activate a function on the turret?

It takes all of Chell's willpower to not jump in surprise when the two start singing one of the only songs she remembers hearing.

The choice of song is an odd one, as she had only listened to it as she was shown the way out of Aperture. Was it the only song the turret knew?

If the circumstances were different, she'd find their duet beautiful. She'd never tell GLaDOS that, though.]