 Chell and GLaDOS return to the modern chambers and face Wheatley , who is driven by GLaDOS 's software to test them against a series of traps , which Chell escapes . In their final confrontation , Chell attaches three corrupted personality cores ( Nolan North ) to Wheatley , allowing GLaDOS a second core transfer restoring her control . With the laboratories ' nuclear reactor on the brink of meltdown , the roof collapses , revealing the night sky , whereupon Chell places a portal on the moon overhead , causing the vacuum of space to pull her and Wheatley through the other portal still inside the chamber . GLaDOS retrieves Chell , who falls unconscious , leaving Wheatley in space with a corrupt personality core orbiting him . 
