Caroline

Caroline is an unseen character mentioned repeatedly in pre-recorded messages and later by GLaDOS. Caroline was the secretary of Aperture Laboratories's CEO Cave Johnson.

Backstory
Caroline was a former model and poster figure of Aperture Science but, as time went by, she became more of Johnson's personal assistant. One day, Cave decided to put his mind and personality into a computer that would run after he died. However, he also decreed that should he die before this takes place, the position would go to Caroline, cautioning that she would have to be pushed into the role because she is much too modest. After Cave's death of kidney failure, Caroline's brain was transferred to the network, which would be infamously known as GLaDOS herself. The artificial consciousness designed by Aperture Science proved to be extremely problematic, with GLaDOS trying to kill the factility's scientists within one sixteenth of a picosecond every time she was activated. It seemed that Caroline's innocent personality could not supersede the self-aware machinations of GLaDOS's computer brain. The name Caroline also has risen some thoughts as her name means "free man" She is also thought to be Chell's Mother. Proof of this is found in the turrets' song at the end of Portal 2, who's lyrics are this: Cara bel, cara mia bella. Mia bambina, a﻿ tra che la stima che la stima. A cara mia, addio! Mia bambina cara, perche non passi lontana si﻿ lontana da scienza? Cara cara mia bambina. A mia bel. A mia cara. A mia cara. A mia bambina. A cara, cari a mi! (My dear, beautiful darling, my child that i admire.To my dear, farewell! My dear girl, why not walk far away from science? My dear, dear girl. To my lovely. To my dear. To my dear. To my child, My dear, dear to me!)

Portal 2
While she did not physically appear in person, she can be heard through audio loops in some chambers and is almost always mentioned by GLaDOS, more over as she bluffs coming back to her former self. While trapped in a potato and exploring some of the oldest segments of the Aperture Science centre with Chell, the Caroline personality begins to reemerge from GLaDOS, described by GLaDOS herself as a sort of conscience. At the end, GLaDOS thanks Chell for helping her discover Caroline's personality segment - and its location, she summarily deletes it shortly after regaining her former body from Wheatley, in which a sudden mood shift is noticed and GLaDOS immediately reverts to her regular self. However, the ending song implies that GLaDOS merely lied in order to make Chell leave the facility, and hints at Caroline still residing within her. It is possible however, that this story element was simply inserted into GLaDOS' dialog, after the song was recorded. This is supported by the fact that her "conscience" appears to be gone during co-op, after the main storyline chronologically, in which she occasionally rewards players for killing each other ("that was just cruel. Orange gains 15 science collaboration points") or shows disrespect towards humans ("now, now, Blue isn't a human. Orange loses 3 science collaboration points"). However, it is worth noting that near the end of the co-operative chambers, GLaDOS begins showing worry and anxiety once again while the two bots get closer and closer to the finale. Whether this is a ruse or not, is unknown at this time.

Portrait of a Lady
In a hidden room overlooking the first test chamber in the 7th chapter, "The Reunion", a portrait can be found, illustrating CEO Cave Johnson with an unknown woman standing beside him. The woman is dark-haired and is wearing a white dress, and while unconfirmed, the woman is likely to be Caroline. When finding the portrait, the "Portrait of a Lady" achievement unlocks, while GLaDOS comments the picture.

"Those people, in the portrait. They look so familiar..."

- GLaDOS