The plot of Portal is revealed to the player via audio messages from GLaDOS and side rooms found in the later levels. The game begins with protagonist Chell waking up from a stasis bed and getting instructions and warnings from GLaDOS about the upcoming test chamber experience. This part of the game involves distinct test chambers that the player has to complete to go on to the next test chamber. Chell is promised cake and grief counseling as her reward if she completes all the test chambers.
Below are the characters on the site that cosplayers have depicted.