Welcome to The Merchant of Aperture. Before reading the story proper, why not peruse these bits of information on the personality cores as they appear in this story. If you want to be surprised during their first appearances, ignore this and move on.
Curiosity Core (Marie Curie) - A promising young intern, with a seemingly never ending thirst for knowledge. Her constant questioning both got on the higher level employee's nerves and made her a perfect candidate for the Distraction of Murdering Via Curiosity Initiative.
Anger Core (Sue Ripley) - One of the mental patients Aperture attempted to use for testing. Seemingly androgynous, his/her anger issues resulted in the subject simply sitting in the middle of the chamber making angry growls. The scientists felt he/she would perhaps give GLaDOS more human emotions, and thus have her sympathize with the scientists rather than try and kill them with deadly neurotoxin.
Logic Core (Isaac Stevens) - Aperture's second attempt at an intelligence core, Isaac was a baker who worked in their employee cafeteria. In a mandatory IQ test he scored 180, and was immediately given a "promotion".
Morality Core (Unknown) - Desperate to control GLaDOS, with all other cores having failed, Aperture used one of their test subjects, a mute woman who in her application form listed a "rigid moral code" as a strength to make the final produced personality core.
Wheatley (Wheatley Pendleton) - Aperture Science's Public Relations Agent was hired for two reasons. First, he was an absolute and total moron, and thus would be far too stupid to notice any moral issues and would believe (and parrot back) everything he was told. Second, he never. shut. up, and thus could give long speeches about the safety of Aperture's Products, or how they never, ever kidnapped orphans and hobos off the streets.
Rick (Richard "Rick" Venture) - One of the security guards tasked with preventing Black Mesa infiltrators from stealing company secrets, and preventing experiments from escaping. Rick was a huge fan of the Oklahoma Ford movie series, and dreamed of one day becoming an "adventologist" (basically a movie type archaeologist without the science and twice as much adventure). He would frequently regale the other employees with his past "adventures" of dubious truth. Rick was one of the first cores, made primarily to see if Aperture could do it.
Space Core (Neil Shepard) - Son of a famous astronaut who went missing during the infamous 1960s incident, he went crazy and became obsessed with space and finding his father. He continuously pestered Aperture employees to let him "go to space" and eventually they agreed, if he's just participate in one little test first…
Fact Core (Craig Allen) - Aperture's most brilliant scientist, who had a memory that bordered on encyclopedic. They attempted to upload him into a personality core to preserve his intellect for eternity, but something went horribly wrong. His brain was scrambled, and the information he once knew jumbled together in a factual mess.