Wheatley

"'Oh, brilliant! You did find a portal gun! You know what? It goes to show: people with brain damage are the real heroes in the end, aren't they? At the end of the day. Brave.'" -Wheatley to Chell when he sees her with the Handheld Portal Device The Intelligence Dampening Sphere, commonly known as Wheatley, is a personality construct with a British accent and is the deuteragonist of Portal 2. After he gains control of Aperture Laboratories, however, he becomes the game's antagonist in the second half.

Background
Wheatley first appeared in Aperture Laboratories as an Intelligence Dampening Sphere, designed to be attached to GLaDOS to make her behave by generating an endless stream of terrible ideas. A few years later, for unknown reasons, he was deactivated and put into the construct's storage.

Prior to the events of Portal 2, Wheatley took control of the Extended Relaxation Center; a place designed to keep test subjects in cryogenic storage before being released into the test chambers. Many centuries later, Wheatley decides to escape the facility. In order to do so, he needs assistance from one of the test subjects, but they don't run out of cryogenic supply until even more centuries later. Luckliy, Chell was the only one who ended during that time.

Portal 2
Wheatley first appeared at the introduction of the game. He accompanied Chell while he moved her Extended Relaxation Center into her ruined relaxation vault from the first game, so she can find the Handheld Portal Device and help him escape. After Chell finds the portal gun, he disengages from his management rail and together they head off to GLaDOS' chamber and access a breaker room escape room. Unfortunately, Wheatley operates it incorrectly and accidentally reboots GLaDOS. Wheatley gets crushed to death while Chell is delivered to an incinerator to test for the remainder of her life.

During Chapters 2, 3 and 4 Wheatley, miraculously alive, observes Chell on his management rail (reconnected during a conflict with a bird) during her time trapped in the test chambers. At the conclusion of Chapter 4, Wheatley speaks in an accent "beyond her range of hearing", even though she can clearly do so. He opens panels that allow Chell to escape through the catwalks. During their time free, they replace her sentry turrets with defective turrets and implode the neurotoxin generator. Wheatley and Chell head through a tube that leads directly to GLaDOS' chamber to confront her. GLaDOS soon becomes corrupt due to her obsession of wanting to kill Chell. The Announcer calls for a core transfer. Wheatley gets inserted into a core slot and eventually transferred into the central core's body. Finally, his plan is successful and summons the escape lift to let Chell leave while he stays controlling the facility. But, he becomes mad with power and decides to wonder why she should leave.