2. References to "The Bird"
Despite being an all powerful super computer GLaDOS obviously weakness appears to be Ornithophobia. There are many unanswered questions about the appearance of this solitary bird in Portal 2 such as how it got that deep into Aperture labs, how it survived, whether this proves the existence of intelligent life above ground and why the only living creature (asides from Chell) to be featured in Portal 2 is this solitary bird. At one point in the game it appears that the bird is looking over a nest although whether he - or she - is protecting eggs was left completely unexplained until the DLC at which point GLaDOS interacts with some baby birds in Art Therapy. This in itself poses a more fundamentally important question as to where the birds' mate is? The Caroline portrait and the possibilities of it's meaning come back to us at this point. It also leads to a different theory which is perhaps even more fascinating: the many, many connections between Portal 2 and the Greek legend of Prometheus, who was "punished by the gods for giving the gift of knowledge to man...cast to the bowels of the earth and pecked by birds." Many cultures have different superstitions regarding birds in the house. In traditional Irish culture, for example, if a bird flew into the house, it was a portent of death. Interesting that GLaDOS is being pecked by birds as Chell awakes from her fall into the bowels of Aperture science. Maybe you're both already dead by this point? In fact, perhaps the whole game is a mythology based around death, which just sees Chell on a journey to the afterlife.