Explaining That Strange Choice- Why he gave the stone to Thanos
After their initial plan to separate Thanos from the infinity gauntlet is ruined by a grieving Peter Quill. Thanos easily takes down all of the heroes and is about to strike the killing blow against Tony Stark when Stephen Strange offers Thanos the time stone in exchange for sparing Tony’s life. But why would he make such a huge sacrifice, after previously warning Tony that protecting the stone is his only priority?
For the answer, we have to rewind a bit to before Thanos shows up when we see Doctor Strange looking ahead to see “all the possible outcomes” of their battle with the Mad Titan. Out of millions of potential scenarios, Stephen tells Tony that they only win in one and when the fight ends then strange says that it was the only way. Which clearly show that strange already seen this through.
While we don’t know what Stephen sees, it’s a safe bet that the key to defeating Thanos relies on Tony being alive for some reason, even if that means the Sorcerer Supreme has to sacrifice himself (and billions of others) to give Tony and the other surviving Avengers a fighting chance somewhere down the line. All the real Avengers are still alive. There is a possibility of winning this war and go back in time to save half of the heroes and peoples that are died.