in MK 4, when Scorpion learned that it was Actually Quan Chi who killed him and hi family and Clan, Scopion pretty much Forgave Sub-Zero. at one point, Scopion said he would protect Sub-Zero. As for Noob Saibot when might see a war between the Lin Kuei and the Brotherhood of the Shadow with Smoke stuck in the middle which might be The reavealing of Noobs true Identity. But then again there may not be a war and Noob may Just come out with it.

Sub-Zero had last seen Scorpion before both Quan Chi and Scorpion were banished to the Netherealm. I think that Sub-Zero thinks about Scorpion in the back of his mind but he has other things to deal with. I also feel that Scorpion thinks just the way Sub-Zero does.

In Deception, we now know who Noob Saibot really is and in a future game Sub-Zero and Scorpion may cross paths again to deal with the threat that is in Noob Saibot. Sub-Zero would want to face his brother in a noble cause while Scorpion may just be out for blood. I could see both Sub-Zero and Scorpion fight on the same side, but they will always be in conflict with each other due to their feelings towards Noob Saibot.

While I seriously doubt we will see Sub-Zero and Scorpion becoming friend's anytime soon, I believe they may be considered rough allies. As for Noob Saibot, I doubt he really cares about Scorpion anymore. Depending on how twisted he is, he may actually be thankful to Scorpion for his new "Life". But I think those two have drifted too far apart for a rivalry to rekindle. Scorpion has learned the truth about who murdered his family and clan, and Noob is pursuing his own goals. I think they are pretty much done with each other.