Alright, im gonna make a timeline of events regarding this story to end all confusion
MK Mythologies Sub Zero - Scorpion and ORIGINAL sub zero are BOTH hired by Quan Chi to steal the sacred map of elements for him, in case one fails. Both scorpion and sub zero are unknown to this and when they meet, the fight to the death since theyre from rival clans. Sub Zero kills scorpion and returns to the lin kuei palace and gives the map to quan chi. As payment, quan chi kills scorpions family and clan so the lin kuei doesnt have to worry about another rival clan.
Pre MK1 - Scorpions soul is brought back to life as a spectre (we now know quan chi does this from scorpions bio video). He is under the impression that sub zero murdered his family and clan and swears revenge.
MK1 - Scorpion kills sub zero in battle and thinks he got his revenge.
MK2 - Scorpion sees sub zero again and is outraged because he thought he killed his rival. However, this is YOUNGER sub zero. Scorpion realizes this because he sees younger sub zero spare the life of a defeated opponent. Scorpion then vows to be the protector of the younger sub zero in atonement for killing his brother.
UMK3 - Scorpion gets enlisted as one of shao kahns warriors to eliminate the earth warriors. However, he sees that sub zero is part of the earth warriors, so he switches sides and helps earth defeat kahn.
MK4 - Scorpions soul has no purpose now basically. However, Quan chi then deceives scorpion by claiming that younger sub zero had something to do with the murder of his family and clan. Quan Chi does this because he wanted to use scorpion to defeat sub zero, who could possibly get in the way of shinnok and himself. Outraged, scorpion vows to exact revenge and takes back his oath to protect younger sub zero. He defeats sub zero in battle and before he was about to finish him, sub zero kept telling him he did not kill scorpions family and clan. Quan Chi then reveals himself to be the murderer and then told scorpion he was using him. While Quan Chi was trying to send scorpion back to the netherrealm, scorpion ran at him, which resulted in both of them being sent to the netherrealm. From MK
A onwards, scorpion is hunting Quan Chi.
Now, since the upcoming game is a reboot and we are following the events of MK 1 - 3, we have to think in terms of that story. Quan Chi doesnt get introduced until MK4, so it makes sense that in scorpions bio video, it says that OLDER sub zero killed his family and clan.
And for thexx25, sub zero is actually half american, half chinese (or japanese, cant remember lol). i guess they decided to ultimately make him more white, because its been the case since MK3. They did the same thing with Kano, originally he was American Japanese, but the movie adaptation of Kano was so well received as an australian, they made him australian in the later games as well.