The climax of Avengers: Infinity War is something the fans will see in their nightmares for some time to come. Despite Avengers: Endgame and Spider-Man Far From Home trailer signalling that time travel may bring back the superheroes who died during the decimation, it is still one of the most shocking climaxes of recent times.However, among those who were killed by Thanos and those who were spared, the one name that stood out was Captain America. Thanos could have killed him in the last few moments of Infinity War but spared his life instead. A new fan theory now aims to explain what really happened and why. Other than Cap, he left characters like Iron Man, Thor, and Black Widow alive. [Infinity War] Captain America vs. Thanos from r/FanTheoriesThe fan explained his theory thus…So Thanos doesn’t consider himself a bad guy. In his mind he is the hero of this story and everyone else is misguided. I say misguided because even though he sees himself as the good guy; it doesn’t mean he actually thinks everyone trying to stop him is a bad guy.And because he is the good guy in his mind he doesn’t kill for any sort of pleasure, mostly only out of a misguided sense of duty. I think the only reason he killed Loki and Heimdall himself is because he saw they could seriously screw with his plans if allowed to live. Otherwise, much like Javier Bardem in No Country for Old Men, he leaves death up to a certain amount of chance instead of being his choice.Finally, before I get to Captain America, I would like to point out that he sees admirable traits in others which he truly respects. He said he liked Starlord. He knew of and respected Tony. Which brings us to Cap.When he was fighting in Wakanda, he himself only “killed” Vision. Everyone else he merely disabled.How was Captain America able to catch his hand and hold it? Because Thanos was trying not to hurt him. He only looked at Captain for a minute like that because he found something interesting in Captain America; and maybe he was a bit surprised by how strong or determined Steve was. Rather like how an adult person can get surprised while playing with a kitten.Why did he need to use his other hand to knock Captain out? He didn’t. He just didn’t want to hurt Steve more than necessary, and he didn’t want Steve to hurt himself trying to fight him. (Because we all know Steve would have fought until he was dead.)If Steve died in the Snap, so be it. But he wasn’t going to chose to end Steve’s life because that wasn’t his purview.In the larger Marvel Cinematic Universe, the existence of Iron Man and Captain America beyond Avengers: Endgame is unlikely given the contracts of actors playing them both – Robert Downey Jr and Chris Evans – are about to end soon. “Officially wrapped on Avengers 4,” Evans had earlier written after wrapping shoot for Endgame. “It was an emotional day to say the least. Playing this role over the last 8 years has been an honor. To everyone in front of the camera, behind the camera, and in the audience, thank you for the memories! Eternally grateful.” He has been a part of MCU for almost 10 years.Avengers: Endgame releases on April 26.