Marcus lived a disreputable life of petty crime alongside his brother, whom he accidentally got killed during a botched car-jacking which also saw the deaths of two cops. Marcus was arrested, convicted, and sentenced to death at the Longview State Correctional Facility. During his time on Death Row, Marcus was visited repeatedly by Dr. Serena Kogan, a cancer-stricken scientist who wished for him to sign over his body to her research project. He refused her request up until the day of his execution, upon which he agreed to sign it over in exchange for a final kiss.
Marcus was then strapped onto a cross-like table and shown to his weeping friends and relatives before being executed by lethal injection. It is ambiguous as to whether the injection actually killed him or simply placed him in a coma for Serena's project, however. Marcus' body was taken apart and converted into a unique cyborg, one that still retained his human brain and heart. He was then stored in an underground facility where he would remain in stasis for 15 years as Judgment Day occurred in the world above. Skynet would later discover his body and add further enhancements to his design, completing the seemingly abandoned work of Cyberdyne Research.
In the futureEdit
Marcus awakens/is activated in the remains of a SkyNet RnD lab and staggers out into the rain-soaked terrain, disoriently screaming in horror at the world around him. After composing himself, Marcus takes the clothes of a deceased Resistance fighter and starts a long walk through the desert, finding a sand-caked road leading into Los Angeles. Upon arriving, Marcus observed the ruined city from atop the Hollywood banner and then descended into the streets where he encountered a Series 600 Terminator patrolling the city.
Ignorantly, he called out to it, only to immediately come under fire from the machine's mini-gun. Before he could be mowed down, however, Marcus was tackled to the ground by a young man called Kyle Reese; who told him: "Come with me if you want to live." Following Kyle's lead, Marcus bolted for the nearby building while the T-600 struggled to free itself from a trap the youth had set. It escaped by shooting off its foot, however, and promptly took chase. Up on the roof, Kyle's young companion, a mute girl named Star, released another trap, crushing the T-600 beneath heavy machinery.
Kyle then held Marcus at gunpoint, accusing him of stealing the uniform of a Resistance fighter, but the cyborg easily disarmed him and demanded to know the date and what happened to the world. Kyle answered his questions, and Marcus expressed an interest in reaching a Skynet-controlled location. Before they could decide on this, an HK-Aerial flew in overhead, toppling a building as it passed. Knowing their safety had been compromised, Kyle led Marcus and Star back to their hiding place. Here, Marcus demonstrated how to tether the shotgun to his arm to avoid losing it to an opponent. He then fixed their radio, picking up a message from John Connor in the process.
In the morning, they traveled to Griffith Observatory to find transport away from Los Angeles. While repairing an old Jeep, Marcus accidentally cut himself on a wire and was given a band-aid from Star. He then got it working and inadvertently activated the radio, which started playing "Rooster" by Alice in Chains, much to Kyle and Star's surprise. Though because it was a song his late brother used to listen to, Marcus switched it off and barked at Star to get out of the passenger seat. They were then attacked by an Aerostat and Kyle attempted to lose it by driving down the hill haphazardly. Marcus eventually destroyed it with a tire-iron, however. Unimpressed by Kyle's driving skills, Marcus promptly kicked him out from behind the wheel. Stopping at an old gas station bearing the mark of the Resistance, the trio are confronted by a gang of survivors who view them as a threat. Their de-facto leader, Virginia, offers them food and water, however, much to the annoyance of another refugee named Len. Star then senses vibrations in the ground mere seconds before a Harvester smashes through the roof and snatches Virginia and several other refugees. The trio flee outside and try to get aboard some of the escaping vehicles, but they speed away and leave them behind. Kyle quickly realizes that attempting to escape will only result in their death as the Harvester destroys the fleeing vehicles with its plasma cannon. Marcus takes a moment to observe the machine before getting into an armored truck and using it to push a gasoline tanker into the legs of the Harvester, which succeeds in toppling it. As they drive away, Kyle tries to shoot the gas with his shotgun, but is unsuccessful in sparking it. Star solves this problem by giving Marcus a flare which he then lights and tosses onto the gasoline, lighting it and causing a big explosion around the Harvester. It is not destroyed, however, and releases two Moto-Terminators that give chase. Kyle is able to shoot out the first, and is saved from being splattered on a school bus by Marcus in the process. The second is disabled when Marcus instructs Kyle to lower the ball-hook, which catches the machine and drags it behind them.
The chase leads them to a bridge where they are cut off by an HK-Aerial, which fires at the bridge, forcing Marcus to screech to a halt. As a result, the Moto-Terminator swings up and around the HK, disabling one of its engines in the process. As the HK struggles to remain airborne, the truck is spun around until it almost topples off the edge. Kyle and Star subsequently fall out of the vehicle and are caught by the Harvester standing upon the HK-Carrier below. The HK-Aerial breaks free and fires upon the truck, forcing Marcus to jump onto the Carrier with an axe, which he then uses to try to free Kyle and Star from the cattle pens. The Harvester grabs him, however, and slams Marcus into the Carrier's hull.
Before it can destroy him, the Transport is attacked by two Resistance A-10 Warthogs, one of which was piloted by Blair Williams. During their missile attack, Marcus is dropped by the Harvester and falls into the river below. The two aircraft are then shot down by the HK-Aerial and the Carrier escapes. Marcus comes to at the riverbank and makes his way back into the desert where he encounters Blair hanging from a telephone tower, having ejected from her bird before its destruction. He helps her down, and in return, she offers to take him to John Connor, as he might help Marcus rescue his friends from Skynet Central.
They stop at a derelict racetrack overnight where Blair removes her top in the rain to tend to an injury on her collar, catching Marcus' attention with her semi-nakedness. While Marcus is away gathering kindling, Blair is attacked by a gang of humans who want her supplies. Marcus arrives in time and viciously beats them into submission, stabbing one in the shoulder with a screwdriver in the process. Afterward, Blair curls up to him to share his body heat next to the fire, and notices how strong his heart is before falling asleep in his arms. Marcus wonders if he's a good man and whether or not he deserves a second chance in life.
In the morning, they arrive at the Resistance base and travel through a minefield laced with magnetized landmines. As they pass through, a mine attaches itself to Marcus and explodes, injuring him. He is then carried to the infirmary where Kate Connor tends to his wounds, despite his declarations of being fine. Upon opening his shirt, she discovers the endoskeleton exposed beneath and calls for Barnes, who swiftly knocks Marcus unconscious with the butt of his rifle. He is then chained up and suspended in a missile silo where he is examined by John Connor.
Marcus protests that he is human, but John responds by removing the chain holding his head, allowing Marcus to see the exposed metal in his chest. He cries out in horror at what he's become but insists that he is not just some machine. John is convinced that Marcus was sent there to kill him and the leadership, however, and mentions Kyle Reese (his paradoxical father). This prompts Marcus to inform John of Kyle's capture by Skynet, which rattles him significantly.
Marcus is then left alone with Barnes, who shoots him in the chest for his late brother who died on a mission on Skynet VLA a few days earlier. Blair arrives moments later and tells Barnes that John wishes to see him, shooting Marcus in the process. Barnes falls for her ruse and leaves, granting her the chance to lower Marcus to the bottom of the silo and release him from his chains. Barnes soon returns, however, and fires a rocket at the escaping couple, but they are able to flee through a ventilation shaft.
They follow it back to the minefield as the Resistance mobilizes to stop them. Blair uses a magnetic wire to trigger a line of mines, allowing them a safe path to the Jeep, only for it to be destroyed by a rocket. Forced to improvise, they flee to a wall where Marcus holds his hand out to draw their fire while Blair shoots out the floodlight, granting them cover of darkness. She is shot in the leg, however, which slows their escape. Marcus shields her from an explosion and gives her his coat, which she wears to confuse the soldiers.
While she's captured, Marcus steals a bike from a soldier and uses it to jump the perimeter fence and takes one last look at Blair before running through the woods while under fire from John's helicopter. He is briefly incapacitated by John's assault, and is then severely burned when John launches a napalm attack. However, while searching the river for him, John's helicopter is attacked by Hydrobots and the pilots are killed. Marcus intervenes, however, and destroys the last Hydrobot, saving John's life.
He is then held at gunpoint, as John threatens to shoot Marcus in the heart. He makes John an offer, however: allow him to go free, and he'll get John into Skynet Central to save Kyle. John agrees, giving Marcus a comm device to contact him with once he's inside. Marcus promises to uphold his end of the bargain before swimming away as the Resistance arrives. He makes his way to the Skynet perimeter in San Francisco and confronts a turret, which identifies him and allows him safe passage. Upon making his way into the core building of Skynet Central, Marcus interfaces with Skynet's database by synchronising with his CPU. He orders the turrets at the north entrance to stand down and then transmits Kyle's location to John, who is waiting on the outskirts of town. Afterward, Marcus researches his death and the activities of Dr. Serena Kogan prior to that, learning that she also succumbed to her cancer and that her work at Cyberdyne was adopted by the US Air force. The stress of maintaining the connection overwhelms Marcus, rendering him unconscious.
He awakens in a diagnostic chair, his damaged flesh fully repaired and his clothes replaced with white garments. Upon happy to see he is "human" again, Skynet appears to him in the form of Serena on the screen and welcomes him "home", and then goes on to explain his purpose as the perfect infiltrator and his mission to find Kyle and lure John to his death, all the while showing him CCTV footage of John fighting the T-RIP, a prototype T-800. Sickened by his use as a pawn, Marcus tears the CPU from the back of his head and snarls at Skynet that he will save John.
Skynet offers him the chance to serve the machines, stating that he's no longer bound by the human condition, but Marcus proclaims that he ishuman and destroys the glass screen before hurrying to John's aid. He tracks John to the Terminator Factory beneath the building and finds him in the grip of the T-RIP. Marcus charged the machine and tackled it to the ground, allowing John to crawl away. The T-RIP threw him off and headed back to John as the skin on Marcus' left hand was burned away by molten steel. Enraged, Marcus attacked the machine from behind and hurled it into a pylon. He then picked up a piece of metal railing and started beating the T-RIP with it, but it caught his wrist and kicked him away. Seeing John working on T-RIP power cells to make an explosive, Marcus decides to sacrifice himself by allowing the T-RIP to beat him repeatedly with a cinder block. It scans his body and discovers his heart, identifying it as a vulnerability, and punches him in the chest with all of its strength. The blow is sufficient to stop his heart, and Marcus is terminated.
However, Marcus is revived by John, who uses a power cable to give him an electric shock while the T-RIP is encased in metal. After reviving him, John is impaled through the chest with a steel bar by the T-RIP. Marcus jumps to his feet and breaks the steel bar, using half of it to decapitate the machine with ease. After terminating the T-RIP, Marcus carries John out of the factory. Then they meet Barnes, who helps Marcus carry John to the helicopter where he is reunited with Kyle and Star. As their helicopter flees the area, John detonates the explosive, destroying Skynet Central.
Back at a Resistance outpost, Kate Connor tends to John's injuries and informs the others of his imminent death due to the damage suffered by his heart. Believing that John deserved a second chance, Marcus tells Kate to take his heart and give it to John to save his life. He says his final goodbyes to Kyle and Star, and kisses Blair before undergoing the operation. In his final moments, he looks to John, who acknowledges his trust and gratitude towards Marcus with a respectful nod.
By giving his life to save John, Marcus completed his original intention of donating himself to a better cause.