Mortal Kombat’s version of Sub-Zero stays pretty loyal to the video games, but the character is still changed in a few big ways. Though he works for Shang Tsung, and by extension Shao Kahn, Sub-Zero is really the main villain of the movie, acting as the primary rival to both Scorpion and Cole Young. And with Joe Taslim signed on to play the character in multiple other movies, Sub-Zero will likely continue to play a big role in Mortal Kombat 2.
In the MK video games, Sub-Zero – real name Bi-Han – is a warrior of the Chinese Lin Kuei clan of assassins. Bi-Han is hired by the Netherrealm sorcerer Quan Chi to retrieve an item from a sacred temple. Unknown to Sub-Zero, Quan Chi also hired Scorpion, a ninja of the rival Shirai Ryu clan, to do the same job, hoping that at least one of the two would be able to accomplish the task. The warriors meet in the temple and, after a fierce battle sparked by their clans’ feud, Sub-Zero kills Scorpion. As payment for completing the task, Quan Chi wipes out the rest of the Shirai Ryu. Scorpion eventually rises from the grave to exact his vengeance on Sub-Zero, who himself is then resurrected as the shadow wraith Noob Saibot.
That story’s twisted somewhat in Mortal Kombat 2021. For starters, the movie version of Sub-Zero is far older than the game version. The film shows Sub-Zero battling Scorpion in the 17th century, suggesting that his modern-day self is kept alive largely by dark magical powers. That’s not the case in the games, where Sub-Zero is born in the present day. The nature of the Scorpion feud is also quite different. In the movie, Sub-Zero actively seeks Scorpion out and wipes out his family personally, rather than the whole thing being some elaborate scheme orchestrated by Quan Chi. That change makes Sub-Zero a much more explicit villain from the very beginning, rather than the more morally gray antihero of the earlier games.
Sub-Zero’s ice powers are also a bit different in the MK reboot, as the games don’t feature the arcana explanation for the fighters’ magical abilities. In the games, Sub-Zero’s magic is learned from the Lin Kuei, rather than the result of some internal power. The cryomancy manifests in a very similar way in the movie, however, with Sub-Zero using several iconic moves like his Ice Shower, Ice Shatter, Ice Clone, and Kori Blade.
Overall, the movie Sub-Zero is pretty similar to the character’s video game self. He has comparable powers and similar motivations, and his relationship with Scorpion is effectively the same. The changes that are made all serve to make Sub-Zero more of an overt villain, which makes sense given his role in the movie. If Bi-Han rises from the Netherrealm like Scorpion in Mortal Kombat 2, he could become an even more dangerous foe.