I've been waiting for you.
After a T-1000 was sent back in time by Skynet to assassinate young Sarah Connor, the Guardian was sent to 1973 to protect her, anonymously as its memory files were erased, so that no one would know who sent it. Guardian saved Sarah, but her parents were killed by the T-1000.
Thus, it raised Sarah by itself and prepared her by teaching her how to defend herself against Skynet's assassins, along with forewarning her about key moments in her future. The Guardian also told Sarah about the role her son, John, would play in Skynet's downfall. Over the many years they spent together, Sarah formed a very strong bond with the Guardian, whom she sees as a father-figure and refers to as "Pops" and taught the T-800 restraint, leading the Terminator to attack only to disable and works on teaching it to blend in, though without too much success.
When the T-800 sent by Skynet to assassinate Sarah arrived at Griffith Park Observatory in 1984, the Guardian confronted it in a fight. It held the other T-800 off long enough for Sarah to deactivate it with a .50 caliber round to its chest. The two then traveled to downtown Los Angeles to save Kyle Reese, who was under attack from the previously mentioned T-1000. They were able to rescue him, but Kyle was shocked by the Guardian's presence in the vehicle. During a short fight, Guardian incapacitated Kyle by knocking him unconscious using the barrel of Kyle's gun. When Kyle woke up, Guardian and Sarah explained him the changes to the future and that they'd been preparing for his arrival for over a decade. As they talked, Guardian detected and shot off a Mimetic polyalloy tracking device from the door of their truck, which the T-1000 had been using to track them down.
The T-1000 successfully tracked them down and, after a brief car chase, found them in an abandoned warehouse. Upon arrival, it impaled Guardian with a pole formed from its own mimetic polyalloy through the shoulder, pinning it to a wall and temporarily incapacitating it while the T-1000 went after Sarah, reactivating the damaged T-800 with a drop of its mimetic polyalloy in order for it to kill Kyle. Kyle managed to deactivate the T-800 once again and Sarah lured the T-1000 into an acid trap to dissolve it. Despite being badly damaged, the T-1000 managed to make it through the acid and strangled her, but Guardian, having freed itself from the pole by then, grabbed the T-1000 and held it under the acid to completely dissolve it. However, doing this also dissolved the skin on Guardian's right arm before Sarah neutralized the acid so it would not damage his endoskeleton. Guardian and Sarah then removed the decapitated T-800's CPU and dissolved its body in acid so it could not be found and used to create Skynet by reverse engineering as initially happened.
The Guardian and Sarah revealed Kyle their plan: they intended to use the Time Displacement Equipment that they had developed to travel to 1997 to prevent Judgment Day by destroying Skynet before it was ever created. They needed the T-800's CPU to act as the time machine's operating system. Due to its damaged skin, which would take years to regrow, Guardian could not make the trip as was originally planned as the magnetic field would destroy it. It would instead take "the long way" and prepare for their arrival in the future. While preparing the Time Machine, Kyle remembered "Genisys" from his time jump and told Sarah and Guardian about it. The Guardian confirmed that it was possible for Kyle to remember the memories of an altered timeline by experiencing a nexus point while he was inside the other Time Machine, convincing Sarah to jump forward to that time instead. Guardian sent them forward in time to 2017 and remained behind.
1984 to 2017
Guardian continued to gather equipment, supplies, and weapons for Kyle and Sarah's use in raiding Skynet in 2017. Over the years, its skin sheath regrew so it appeared completely human again even if it was elderly. During the preparation period, Guardian took a position as a member of the construction crew for the Cyberdyne Systems Headquarters to gather intelligence and added Kyle and Sarah's data into a bunker, so that they could survive the destruction of the building. However, Guardian was eventually laid off. Guardian had also kept a collection of photographs and crayon drawings Sarah had made of the two of them when she was a child, along with her old cassette player. Due to old age and a lack of proper maintenance, its servomotors had started to degrade and occasionally experienced lock-ups.
When Sarah and Kyle arrived in 2017, Guardian was not able to intercept them as they materialized above him on top of an overpass in the middle of traffic. It later blamed getting stuck in traffic for not being able to intercept them. It watched as they were arrested and was unable to help them. It tracked them to a hospital and infiltrated the building to rescue them, posing as a visitor. After breaking into the security room, Guardian discovered that Sarah and Kyle were being led to the garage by John Connor. Realizing that John had been converted into a T-3000 Infiltrator, sent to ensure Skynet's creation, it fought John. They were both trapped by the magnetic field of an MRI machine. Kyle shut the machine down long enough to allow Guardian to escape but then switched it back on, leaving John trapped temporarily. They escaped to Guardian's base on the outskirts of San Francisco.
While preparing for their attack on Cyberdyne, Guardian explained John's current state to the pair. It cast doubt on Sarah's belief that John could be saved due to the irreversible nature of his conversion but offered a method of defeating him: a magnetic device that could restrain him. Guardian and Kyle had a slight competition over who could load bullets into clips faster, but Guardian's servomotors locked up and it dropped some bullets due to the glitch caused by the damage from 1984, telling Kyle "I am old". Kyle decided to keep the incident from Sarah. Guardian left the base to build a device, similar to a cestus, that would interfere with the T-3000's magnetic field holding together its Machine-Phase Matter, thus momentarily disabling or restraining it. While preparing that weapon, the T-3000 had tracked them down, forcing Guardian, Kyle and Sarah to flee, using a school bus. During a confrontation on the Golden Gate Bridge, John succeeded in separating the group. Guardian was able to catch up to them and rescued Sarah and Kyle before they fell off the bridge. The trio were then arrested by the police and taken into custody.
During a one-sided interrogation, Guardian detected the presence of another Terminator nearby and attacked a member of the police entourage, revealed to be the T-3000 in disguise. Guardian took the upper hand that time and was able to hold John off long enough for Kyle to fly them off of the roof in a helicopter. John followed in another helicopter and almost succeeded in shooting them down, but after having lost sight of them for a moment, Guardian leaped from their helicopter and smashed into John's, causing them to crash into the lobby of the Cyberdyne building.
While Kyle and Sarah feared for Guardian's safety, it reappeared in time to save them from John by pinning him to a wall with a lamppost. Guardian informed Sarah and Kyle that he had hidden a fallout shelter in the construction blueprints to protect them from the explosion. It had been programmed to identify her and grant her access. The three set out to destroy Skynet by planting explosives, but as they were doing that, Skynet evolved at an astonishing rate, decreasing the upload timer each time. John found them again and began attacking, taking Sarah hostage as a means to prevent Guardian from activating the detonator. Unable to defy its programming to protect Sarah, Guardian gave the detonator to Kyle and attacked John. A brutal fight ensued, in which the detonator was destroyed, but Guardian managed to hold its own for a time, slashing John repeatedly with a laser post and seemingly making him incapable of taking on disguises anymore. However, John eventually gained the upper hand, ripping off Guardian's left arm and throwing him in front of a prototype time machine, helpless. John taunted Guardian about its inability to defeat him, but Sarah and Kyle saved it.
Taking advantage of Kyle and Sarah distracting John, Guardian retrieved its magnetic glove and punched through John's chest, restraining him. Guardian then ordered Kyle to activate the machine which would destroy anything non-organic, including John and Guardian due to its damaged state. Kyle reluctantly complied over Sarah's objections as Guardian dragged John into the magnetic field. Guardian asked Kyle to take care of "his" Sarah as he activated the time machine. Guardian kept John restrained as the magnetic field started to tear them apart, but John eventually broke free of its hold and tried to escape the it. Guardian fought John to prevent that from happening, though Guardian was eventually thrown out off the field and landed in a vat of unprogrammed mimetic polyalloy. John was unable to escape the field and was destroyed, causing the time displacement machine to explode and set off the charges, destroying the Cyberdyne Complex along with any residual machine-phase matter from the T-3000. Guardian survived as it was reactivated by the mimetic polyalloy and used it to repair itself, gaining T-1000-like abilities. With its new abilities, Guardian was able to free Kyle and Sarah from the bunker, initially confusing them as they thought it was another T-1000 when it used its new swords to open the door.
With Skynet seemingly destroyed, they travelled to Kyle's childhood home where Kyle instructed his younger self to remember a message that would help them defeat Skynet. Watching Kyle interact with his younger self, the Guardian gave Sarah his approval in the form of admitting that Kyle is a good man. Believing they were free and have changed the future, Sarah and Kyle decided to make their own future together and kissed. When looked at for approval, the Guardian gave them his version of a smile and they drove off together.
- The Guardian, even before "taking the long way" between 1984 and 2017, is the oldest known active Terminator. It was in the past from 1973 to 1984 and aged accordingly while being shown to be about the same age as the previously shown members of its model in 1973. A Terminator surviving so long is apparently unheard of as Kyle said he'd never seen one so old before and didn't know that their skin sheath aged with them. In 2017, the Guardian was showing its age as well: along with having wrinkled skin and white hair, the Guardian was shown to be in somewhat of a state of disrepair as its servomotors would lock up at times, causing it to have trouble walking and its hand to be unable to grab. This may be due to lack of proper maintenance as a T-800's power cell is good for 120 years. Presumably these problems were fixed along with all the other damage the Guardian took when it bonded with the mimetic polyalloy.
- The Guardian was sent by an unknown party to protect Sarah in 1973. Whoever it is didn't want to be known so they took the precaution of erasing the Guardian's files on them. Sarah believes that this is because if she, Kyle and the Guardian didn't know, Skynet wouldn't find out either and couldn't target them. This indicates that they have an ally out there somewhere and has the resources to reprogram a Terminator, sending it through time.
- The Guardian proves more knowledgeable than the previously seen Terminators, such as having information on the T-3000 and how they were a failed experiment. He also seemed to have a great deal of knowledge of the original timeline and Kyle's part in it, information which he imparted to Sarah. Given that he and Sarah were able to build a crude time machine, this was likely from his knowledge database as well.
- The Guardian proves more adaptive than the other Terminators, possibly due to the longer time its been in the past and greater experiences with humans. Notably, it was crafty enough to help Sarah set up traps for its fellow T-800 and the T-1000, showing a knowledge of their weaknesses when the previous T-800 to face a T-1000 in the past didn't know how to permanently defeat it. Instead of declaring that as it was a superior model, he couldn't defeat the T-3000 like the T-850 did with the T-X, he came up with a way to fight and later destroyed him. Also, even without Sarah's guidance, the Guardian proved capable of blending in with humans enough to survive thirty-three years without suspicion and acquire a construction job for building the Cyberdyne building where Genisys was located.
- The Guardian seemed defensive of its age and the shape it was in, saying it was "old, not obsolete." When it has trouble holding bullets due to its failing parts, it repeats this to Kyle who finishes the sentence and seems to decide to keep it from Sarah.
- The Guardian is the only Terminator protector from the future in the films who survives the movie its in and the completion of its mission.
- Like the first T-800 in the original timeline and the other one in Terminator 2: Judgment Day, the Guardian lost his left arm. Unlike them, he managed to regrow it by utilizing mimetic polyalloy.
- Like the T-850 in Terminator 3: Rise of the Machines, Pops also lost the skin sheath around his arm. He lost it twice, once in 1984 and again in 2017.
- The Guardian has terminated two major Terminator enemies in a film: the T-1000 and the T-3000.
- Several times in the movie, the Guardian attempted to appear more human by smiling, including when he got his mug shot taken. However, as Kyle pointed out — he just looked creepy instead.
- Seeing as John Connor had become the T-3000, Pops is the only Terminator that actually kills John Connor on screen.
- Guardian's outfit and look in 1973 is similar to the 1984 T-800's appearance during the West Highland Police Station shootout.
- Throughout most of the series the Terminator has nicknames. He's nicknamed "Pops" by Sarah Connor and "Lurch" by police.
- During his final battle with the evil John Connor, Kyle uses Guardian's own severed left arm to save him, beating John with it while Sarah used a shotgun.
- At one point, Sarah tells Guardian to "bite me", which he is unimpressed with. After a driver shouts at him in 2017, Guardian uses the same line himself on the driver.
- Terminator Genisys (First appearance)