 Having done so , GLaDOS subjects Chell to new obstacle courses until Wheatley helps her escape once again . The pair sabotage the <unk> and neurotoxin @-@ manufacturing plants before confronting GLaDOS and performing a " core transfer " which replaces GLaDOS with Wheatley as the laboratory 's controlling intelligence . He is quickly corrupted by his newfound power and becomes malevolent , and when he attaches GLaDOS 's personality core to a potato battery , GLaDOS tells Chell that Wheatley was intentionally designed as an " intelligence dampening sphere " producing illogical thoughts , created to hamper her own personality . Denying this , Wheatley drops Chell and GLaDOS through an elevator shaft into the laboratories ' abandoned lowest level . Thereafter Chell ascends through the laboratories in order of construction ( the decor slowly changing from 1950s styles to one similar to that seen early in the game ) , periodically hearing audio recordings of Aperture Science 's founder , Cave Johnson ( J. K. Simmons ) , through which the player learns that Johnson became embittered and deranged as his company lost money and prestige , until his poisoning by moon dust , whereafter his assistant Caroline ( McLain ) became a test subject for a mind @-@ to @-@ computer transfer experiment , and ultimately became GLaDOS . Chell retrieves GLaDOS , and the two form a reluctant partnership to stop Wheatley before his mistakes destroy the laboratories . During their search , GLaDOS is troubled by the identification of herself as Caroline . 
