Most of this is taken form the
Official Mortal Kombat Mythologies Website.
Sub-Zero was a Chinese assassin from a group know as the Lin Kuei, and is a descendent from an ancient race of Outworld people called Cryomancers, warriors with the ability freeze.
Born in America, Sub-Zero was the oldest of three children, which included a brother and sister. Their mother wanted a normal life for her sons, who had already been chosen by the Lin Kuei to become warriors for the clan. She tried in vein to hide them from their father whose own life in America was only a cover for his true identity and purpose. Eventually they were found and their father returned with them to his homeland. Their mother and sister were never seen or heard from again.
Sub-Zero learned of his ability as a young adult. It was passed on to him by his father, a fourth generation Lin Kuei warrior himself. The ability to harness the element of cold is one that takes years of practice. It's full potential realized only by those who've mastered it at the latest stages of life. Sub-Zero's skills have the ability to develop much faster than those of the other Lin Kuei. This was realized by the Lin Kuei Grandmasters who picked the young warrior to take his deceased father's place as the next Sub-Zero.
Among his first missions for the Lin Kuei, is one that leads him to a Shaolin temple to steal a sacred map known as The Map of Elements. It shows the way to yet another temple long hidden from the eyes of mortal men. This temple is known as The Temple of Elements, and is built somewhere inside the Himalayan Mountains of Nepal. But, the real treasure is what's housed within the temple's walls. An artifact that predates man's history on Earth... the artifact is known as Shinnok's Amulet.
On this mission, Sub-Zero encountered Scorpion, who was also charged in finding the map for Quan Chi; they fought for it, and though Scorpion begged for mercy, Sub-Zero granted him none and killed him. Upon his return from the temple, Sub-Zero was asked by Quan Chi to defeat the Guardian Gods and retrieve the amulet. This was no simple task, but Sub-Zero completed it without fail.
As he approached the amulet, Quan Chi appeared and took it back to the Nethrealm, and at that moment, Raiden appeared and scolded Sub-Zero for sending the realms to their doom. He ordered Sub-Zero to retrieve the amulet from the Neathrealm and stop Quan Chi.
While in the Nethrealm, Sub-Zero fought against the Brothers of the Shadow, and eventually a more powerful Scorpion, who believed that Sub-Zero had exterminated his entire clan and all remnants of their existence. He wouldn't listen to Sub-Zero and attacked him. Once again, Sub-Zero was the victor.
After he escaped the Prison of Souls, crossed the Bridge of Immortality, and entered Quan Chi's Fortress, Sub-Zero came face-to-face with Quan Chi's personal assassins Kia, Jataaka, and Sareena. He defeated them all and found Quan Chi, who tried to gain Sub-Zero as an ally in the Brothers of the Shadow by revealing to him that the only reason he exists in the Nethrealm is because his soul is tainted with evil. Sub-Zero refuses the offer, and, surprisingly, with the help of Sareena, defeats Quan Chi.
Sareena helped Sub-Zero so that she could also escape the Nethrealm, but her essence was sent to the 5th plane of the Nethrealm by Shinnok himself. Amulet in hand, he challenged Sub-Zero, but lost thanks to his over-confidence. Sub-Zero returned to Earthrealm with the amulet and handed it to Raiden.
Curious about what Quan Chi had said, Sub-Zero asked Raiden about his soul being tainted with evil, and Raiden stated that it was true, and that only Sub-Zero could change this. Sub-Zero returned to the Lin Kuei with this knowledge, and vowed his loyalty to the organization. The Grandmaster declared that another sorceror named Shang Tsung wanted Sub-Zero to participate in a tournament called Mortal Kmbat.
This is where the story gets a tad hazy, because in Sub-Zero's MK1 ending, it states that his only goal in the tournament was the assassination of Shang Tsung by request of one of his wealthy enemies. Most fans interpret that Sub-Zero was asked to assassinate Shang Tsung after he was asked to participate, which was within the two years before the tournament.
After the two years had passed, Sub-Zero was surprised to find Scorpion, still bent on revenge, on the boat leading to Shang Tsung's personal island. Scorpion and Sub-Zero fought in the tournament, but this time the Lin Kuei warrior lost to the spectre, and his soul descended to the Netherealm, free from compassion.
He had to earn his place while he was in the Nethrealm, and became a wraith named Noob Saibot. He ended up joining the Brothers of the Shadow, and ventured to Outworld to spy on the events of the second tournament, and later, the war between Earthrealm and Outworld. Although he was ordered to side with Shao Kahn, his loyalties were to Shinnok.
When Shao Kahn was defeated, Noob Saibot returned to the Nethrealm and became a general in Shinnok's army of darkness. He helped lead the war against the Elder Gods and Edenia.
Once Shinnok was defeated, Noob Saibot returned to work for Shao Kahn, and disposed of several would-be threats to Shao Kahn's rule, including Goro, who had sided with Kitana against Shao Kahn during the war with Shinnok.
When Noob Saibot returned to his master, he realised that Shao Kahn was dead. With this, he came to the conclusion that he could now be his own demon and rule the Netherealm with his own brand of hatred. He ventured into Kahn's dungeons and reprogrammed Smoke to obey only him. With Smoke as his template, Noob planned on creating an army of cyborg demons and taking over the Nethrealm.
My thoughts: I believe that Noob Saibot will achieve his goal of ruling the Neathrealm, but I don't believe that Smoke will help him. His brother, the current Sub-Zero, will play a huge role in getting Smoke away from Noob Saibot, and odds are there will be a confrontation between Sub-Zero and Noob, but I don't think that Sub-Zero will kill his own brother, even though he's already dead and would come back like Scorpion anyway. But with that being said, Noob Saibot can't die, so I believe we'll see him after Armageddon, and that he'll claw his way ot the top of the Netherealm food chain once again. I can picture him reforming the Brothers of the Shadow, similar to the way Sub-Zero did with the Lin Kuei (except that they obviously won't be a force of good).
