Nearly chopping Thor in half, breaking Cap's vibranium shield and raining fire on his own troops are only some of the vicious acts by 2014 Thanos when he travels to 2023 New York to wreak havoc on the Avengers. In stark contrast, the version of Thanos from Infinity War in the main timeline was less harsh and instead more calm and collected. But what exactly caused this difference in character in one of the most iconic onscreen villains of all time?