The Number of Futures:
Doctor Strange had seen 14,000,605 possible outcomes in Infinity War, and he had to live through as well as die in each of these outcomes.
Having a single solo film in his bag, and making a brief appearance in Thor: Ragnarok, Doctor Strange went on to get one of the most important roles in Avengers: Infinity War.
Doctor Strange’s Promise:
He was not just the protector of the Time Stone but was also directly in Thanos’ center of attention. Additionally, he had also sworn to himself in the film that he would do anything to keep the Time Stone safe.
This is also why the sacrifice of the stone to save Tony Stark’s life was such a surprise to fans, who didn’t take much time to put the pieces of this puzzle together.
Strange and Infinity War:
In Avengers: Infinity War, Doctor Strange was seen going forward in time to find over 14 million possible futures before he found the one future that resulted in Thanos’ defeat.
For others, this journey lasted a few mere seconds, but for Strange, he found out that Stark was the key to saving the universe. This also meant that he had to experience every single one of those 14 million possible lives.
Strange had, in Doctor Strange, messed with time and created a time loop, which is along the lines of something similar that was used in Infinity War to see the future.
Therefore, he had to physically live and die in each of these lives. But before he dies, he also has to reset the loop and experience it all over again, which is something we have seen at the end of Doctor Strange.
Possible Outcomes and Possible Futures:
The simple idea that Doctor Strange had to live through each of these futures also shows why he seems so tired and agitated when he comes out of that particular state of mind.
Based on what happened in each of these 14 million and more futures, he may have had to live millions of lifetimes to find the single future that we ended up seeing in Avengers: Endgame.
But then again, since the Ancient One had already confirmed in Doctor Strange that sorcerers did not have the power of seeing what happens after their own death, it could mean that those who were snapped by Thanos did not actually die.
This is also because Strange had seen past their deaths unless their return to the MCU served as loopholes to the whole idea.
Regardless, their return does raise curious eyes as to whether there could be more possible outcomes that could have resulted in a victory that Doctor Strange had not been able to see.
As of now, all the possible outcomes of futures serve as information that is only known by Doctor Strange, which has the potential to be explored more in the upcoming Doctor Strange in the Multiverse of Madness.