This is an amazing expanse from Portal 2.
Portal 1 Edit
Chell finds herself in Aperture, no signs of life. She follows some "tests" created by an entity called GLaDOS. Eventually, the player makes an escapade and attacks GLaDOS head on, escaping the facillaty.
Portal comic: Lab Rat Edit
It is revealed that one other person lives, but it is not revealed to Chell. This person has mental insercurities, and has what appears to be a talking Aperture Cube that talks. The person discovers the power went out, and that Chell will only be able to live for so long before she dies. He redirects all the nourishment to her, before going into cybersleep himself.
Portal 2 Edit
Too lazy to do this right now, and do not know full story.