What is Caroline's fate at the end of Portal 2?

To add to Merus' answer - GlaDOS has already shown she can function just fine with personality cores removed; see the boss fight in Portal 1, and Wheatley-the-tumor in Portal 2. If the "Caroline" personality was the original core (and why not? Aperture Science seems real big on Modularity), there would be nothing to prevent GlaDOS from removing it, just as she "convinced" Chell to remove the Morality Core in Portal 1.

The other option, of course, is that GlaDOS is lying about having deleted Caroline. She's not exactly got a great record as the most truthful of sardonic, all-powerful AIs.

Either way though, it's all just speculation. The only ones who would know for sure are at Valve.

Sort of awkward for me to be answering my own question (especially after Merus and Raven have provided much simpler answers), but here's what I came up with this morning...

Earlier in the game, she says that for the first time, she's hearing the voice of her own conscience, and that it scares her because it's her own voice. Which means that her conscience is the most foreign thing to GLaDOS after her mind had been so heavily augmented -- and that it can be isolated from every other aspect of itself.

So "Caroline" is a symbol of GLaDOS' conscience with a particularly real cognitive manifestation. When GLaDOS says it deletes "Caroline", it's actually deleting its own newfound conscience, in the sense that GLaDOS considers its conscience to be Caroline's "own voice". The rest of GLaDOS is still a Frankenstein of Caroline's time-twisted mind and the various modifications that the Aperture scientists made to her.

As for the delay between when GLaDOS finds its conscience and when it deletes it, the reason might simply be that it had never been able to pinpoint the fact that its conscience was coming from Caroline -- hence Caroline being deleted right as it says "the surge of emotion that shot through me when I saved your life taught me an even more valuable lesson -- where Caroline lives in my brain".

The turrets might not have fired at Chell in the end because even though GLaDOS deleted "Caroline", it hadn't done so before she specifically implored GLaDOS not to harm Chell. That might explain why when GLaDOS sings "(when I delete you maybe) I'll stop feeling so bad", it's transcribed as "[REDACTED]".

I think Raven and Merus' answers are much more straightforward than mine, and as GLaDOS would say, the simple solution is usually the best one, but I thought this interpretation might be kind of interesting too.

I see the 'GLaDOS is Caroline' thing as GLaDOS is a personality core that contains what is left of Caroline. She went crazy because 1) the power of the GLaDOS body makes you a little crazy and 2) It's hard to go through that much and still be who you were. she adapted to that body but it took some work and time; I'm sure her personality changed over that time. After walking around with Chell, GLaDOS remembered who she was before she was GLaDOS and as a result is more 'human' but still knows how to deal with her body so she is here to stay.

A further note on Caroline changing when she became GLaDOS from http://half-life.wikia.com "The system rewards the administrator of constant repeated tests with a euphoric reaction upon test completion, much like a drug addiction. The euphoria diminishes over time, causing a state of withdrawal which can induce insanity. GLaDOS claims that she was sufficiently motivated by a earnest love of science to overcome the withdrawal, but it may still have had effects on her personality. She also describes the maddening influence of the constant voices provided by the personality cores used to suppress her homicidal compulsions." I see this as further evidence that when Caroline became GLaDOS she had major personality changes

As for the 'deleted Caroline' thing I think this is just part of GLaDOS's sense of humor. She frequently lies and mocks Chell for her own amusement. Also this could be seen as a similar thing to someone saying "Just go! I don't want you here anyway!" when they say good bye to a loved one.

Of course she's lying. GlaDOS wants to be feared almost as much as she likes to test. Her reaction to seeing Chell safe probably made her cringe inside and assert her act as the giant murderous computer that still uses a weak excuse for letting you go.

Remember, by this point in the game the portal gun was lost in space. Chell has no means to defend herself, and GlaDOS could have simply redeployed Wheatly's crushers.

In short - GlaDOS let you go because she's greatful to you and doesn't want to kill you by accident in her tests. At the same time, she doesn't want you to think she's gone all soft and mushy. She has an image to uphold... and she is still very evil.

as i see it what GLADOS's personality is build on caroline the love for science is hers but i have heard that caroline was forced to give her personality to GLADOS, being forced to do things can create a lot of negative emotions like hate to all them that forced her "into the machine". That means all her co scientists, i assume her negative emotions was transferred onto the disk along with the rest of her personality, Now imagine a ai in control of an entire science facility, an ai that hates everybody in that facility, hating the staff,loving science and still following aperture's use and destroy mentality and cave johnson's rules that everybody has to test, even the scientists, and you have a deadly cocktail of a controlling ai that forces people to test, kills them after, killed a lot of the staff to gain full control (like she was made for) and that have been sentient from the first time she was turned on but is smart enough to hide it. The only one who foresaw the danger was Douglas Rattmann , but no one listened to him because of his mental illness. As for caroline, maybe she died under the personality transfer, maybe she went insane, maybe she just left Aperture after the transfer, because she felt betrayed by c johnson and everybody else,OR maybe she died on that "Bring Your Daughter To Work Day".

First of all, let me clear something up. You all are ignoring the "Boots" video. In that video, a computerized Cave Johnson tells Caroline to test out the Portal Gun without the boots. After it cuts to the PeTI-style clip, we can see a human falling apart, presumably Caroline, which means she died during that. I have a strong feeling that's when the Aperture employees took her brain and put her in a personality core known as GLaDOS. Then Portal 1 happened, where GLaDOS got destroyed due to her personality cores (besides the main one) were incinerated. Time had passed. Then, at Chapter 6, we can hear both the Caroline recording and GLaDOS say "Yes sir, Mr. Johnson," as if by instinct. Later, at the end of Portal 2, she "deletes" Caroline. However, that's not actually true according to "Want You Gone." So the "Boots" video was her real fate.

As I see it GLaDOS “deletes” Carolin In the sense that she represses her voice. In the words of Doug Rattmann, “You can always ignore your conscience” because GLaDOS did not remember she was Carolin in the beginning. This is also demonstrated in the turret opera “cara Mia Addio” as the lyrics show she is compassionate towards Chell rather than steely and annoyed. This also is show though her behavior in the second half of the game as potatOS she is less aggravated and seems less homicidal. This would make sense if Carolin as a personality core was taken out of her other half the Disk Operating System she was bound to. The opposite was true for Wheatley after he was hooked up to DOS he became more violent and vindictive.