Came across a very interesting article a while back.
It discusses the idea that GlaDos’ true intentions aren’t to kill Chell, but to ultimately have Chell kill her because GlaDOS, despite her omniscient presence over Aperture Science, is still a prisoner.
They’ve got words like these:
The first time I saw GlaDOS in Portal, I was overcome with a distinct sensation that I was in the presence of someone in pain. Troubled. At the very least, immense frustration. At first I wasn’t sure if it was the gyrations of the physical construct of GlaDOS, or if it was the tone of voice, or even the shape of the giant computer hanging from the ceiling itself. I recall pointing out to my wife that there were distinct similarities to a woman hanging upside down, but it was hard to put my finger on just what it was that made me think that. Of course, I didn’t have a lot of time to stop and stare; I was fighting for my (or Chell’s) life.
Go and read.