“There is still more Science to do, isn't there? That was rhetorical, before you work up your lungs for a half-baked response. Of course there is. There always is.”
—GLaDOS, DTG2: One Year Older
GLaDOS is the main antagonist of Portal and a recurring antagonist in the Destroy the Godmodder series. She is an artificial intelligence built to control the laboratories of Aperture Science. Her body was used by the Advanced Superiors as the template to build Project Binary. In Destroy the Godmodder, She was summoned as an entity by TwinBuilder and later joined the Counteroperation in Destroy the Godmodder 2.
GLaDOS was MTT INDUSTRIES' first attempt to create an artificial intelligence that could manipulate code. She was built in Upper Michigan, within the laboratories of Aperture Science. Although the Advanced Superiors desired a power core that could charge the A.I. and give it supernatural properties, in the late twentieth century Aperture Science lacked this technology, meaning that the Superiors had to settle for a robot that based its intelligence and power off of the brain patterns of an organic being in addition to computer power.
It can be safely assumed that the normal events of Portal's continuity apply to GLaDOS' inception in that Cave Johnson, Aperture's founder, originally wished for his brain to be put inside the robot, but when he died due to moon rock poisoning, the brain of his assistant, Caroline, was used, in accordance with his dying wishes. Once GLaDOS was successfully built and MTT INDUSTRIES abandoned Aperture Science, GLaDOS took control of the facility and the events of both Portal games presumably passed.
On December 7, 2012, the beginning of DTG1, the entire facility of Aperture Science, GLaDOS included, was teleported beneath the Upper Michigan area of Universe B's Earth. It is known that personnel within Area 51 attempted to mount an expedition into Aperture Science shortly afterwards, but GLaDOS drove them out through defense systems and neurotoxin. It is also known that at some point, TwinBuilder traveled to Aperture Science himself on "a hunch" and, under the prompting of GLaDOS, went through many test chambers, identical to the ones in the Portal series. TwinBuilder ultimately confronted and successfully killed GLaDOS.
Later on in DTG1, TwinBuilder made a return trip to Aperture Science (a return trip for him, but his first trip out-of-character, since this was one of his first actions in the DTG series at that point), confronting GLaDOS once more. Despite having killed Her earlier, the two were on decent terms, with TwinBuilder convincing GLaDOS to give him Her Turret Army in exchange for some reserves of deadly neurotoxin. Once the Turret Army was destroyed, GLaDOS summoned Herself to the Battlefield.
Since Her alignment was undetermined, GLaDOS had to be bribed to a side, with both the players and the Godmodders attempting to coax Her onto the Anti-Godmodder side and Pro-Godmodder side respectively. The AGs eventually won out, with GLaDOS fighting using deadly neurotoxin and Rocket Turrets to help. However, she was ultimately destroyed by the Glitch. GLaDOS' defunct body was transported back to Universe B, and was idle for the remainder of DTG1.
A copy of GLaDOS was resummoned by the Godmodder in DTG2 thanks to the Wayback Machine. However, this seems to have no bearing on GLaDOS' current state on Earth. Since DTG1, GLaDOS, although unable to act due to being destroyed, grew to depise TwinBuilder for destroying Her Turret Army and inadvertently destroying Her as well. She also seemed to figure out various things about the war in GodCraft, such as the fact that TwinBuilder became the First Guardian of Minecraft.
Eventually, Aperture Science received new visitors as the Advanced Superiors of MTT INDUSTRIES used GLaDOS' technology, the research of Aperture Scientist employees, and a slew of new employees, to construct Project Binary. After Project Binary was successfully constructed, his power core was used to resurrect GLaDOS and give her a new body. GLaDOS became a part of the Counteroperation's special ops team as a result. It was Her job to create a portal powerful enough to breach a hole through the Narrative and enter GodCraft itself. She did this by extracting the Godmodder's code and reverse-engineering Tabletopian chronal technology.
Once the Arrival fleet congregated at Aperture for the last time, which has served as the special ops' base of operations, Bill Cipher activated the portal and the fleet passed through it and into GodCraft. GLaDOS, who cannot move from Aperture, sended a hard-light avatar containing Her essence into the portal, effectively creating a copy of Her. She proceeded to attack the forces of GodCraft upon Arrival, fleeing with the rest of the special ops as the Glitch took over once more. She then waited for the players, and, once they arrived at the Descent, fought against them.
Despite fighting against the players, GLaDOS was ultimately killed by the Godmodder, whereupon Netpatham claimed a Hard-Light Gun as a Spoil of War from Her. Since this was only GLaDOS' hard-light avatar, GLaDOS' real self remained intact in Aperture Science, where she stayed throughout the rest of DTG2. During the epilogue, the Advanced Superiors, seeing no further use from GLaDOS, transported Her and the rest of Aperture Science outside of Universe B.
GLaDOS was an entity of major importance within 7x7 and its sequel, EGGxEGG. In 7x7, she talked with the One about the nature of the kaleidoscopic abyss, saying that it was caused because of a defect in Project Binary, and that it would be fixed by people from outside of reality, although it being fixed would erase everyone's memories of the kaleidoscopic abyss. However, GLaDOS gave the One a pair of Red Sunglasses, saying that they would allow the One to retain all their knowledge of every universe and timeline even after the end of 7x7.
EGGxEGG revealed that GLaDOS acquired the Red Sunglasses at all through Flumpty Bumpty, who used some glass shards, some lens frames, and all of existence to create the shades and give them to GLaDOS. Although GLaDOS was apprehensive about Flumpty's nature at first, once he convinced her that she was in the kaleidoscopic abyss and told her why it had been created, she calmed down somewhat. Flumpty convinced GLaDOS to give the One the Red Sunglasses once he showed up in her chamber by telling Her that without them, She would die.
His explanation was as such: when the One got the Red Sunglasses and awoke back in the real world, he would use his powers to create the power core needed to make Project Binary work. This power core would then be used to resurrect GLaDOS from her destruction in DTG1. So if She didn't give the One the shades, she would condemn herself to death. GLaDOS relented at this, and played her part as shown above.