Since GLaDOS initiated a lockdown, Rattmann was forced to live his whole life hiding between the backstages of Test Chambers in the Enrichment Center. He then took refuge in several departments throughout the facility and began tampering with the initial test subject roster, rearranging Chell to the top of the list as Test Subject #1 instead. GLaDOS in Portal, with personality cores attached.Д«efore the events of Portal, one of Aperture's technicians, Doug Rattmann, successfully evaded GLaDOS' attempts to flood the Enrichment Center with neurotoxin. She confronts GLaDOS in her chamber at the end of Portal, which allowed GLaDOS to develop an even deeper hatred for her after she was awakened at the beginning of Portal 2.

Her first test subject and the series' main protagonist, Chell, was given a warning of GLaDOS' true colors with the help of Rattmann. Since the attack, she has managed the company to her limits. This ultimately led to the negligence of the outside world from realizing Aperture's fate, as all attention had been diverted to Black Mesa and the aforementioned invasion. The destruction of the company also coincided with an invasion of Earth, which had occurred two days after at Aperture's rival company, Black Mesa. However, only a few if not only one of the staff such as Doug Rattmann had survived her attacks along with the series' main protagonist, Chell. Since she was able to take control of half of the facility's features, GLaDOS began killing most of its inhabitants by flooding the Enrichment Center with neurotoxin.

After it became apparent to Johnson that he may die of moon rock poisoning before development on GLaDOS would be completed, Johnson motioned for the scientists to insert Caroline instead.ДЄfter a decade's worth of hard work, GLaDOS was officially activated as part of one of the many events during the company's 'Bring Your Daughter to Work' day. The project began under the oversight of Cave Johnson over the company and was an attempt to create a fully functional, advanced artificial intelligence which was originally intended to be occupied by Johnson as one of his attempts to cheat death. GLaDOS was a creation of Aperture Science, a personality core designed exactly to be fitted as a central computer mainframe.

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