Spoilers for Avengers: Endgame follow below. In October 2014, seven months before the release of the first Avengers sequel Age of Ultron, Marvel Studios announced that Avengers 3 and 4 would be titled Avengers: Infinity War Part I and Avengers: Infinity War Part II. This signaled that there was a massive, Thanos-infused story still to come, and that it would be too epic to contain to one single movie. Two-part conclusions aren’t exactly rare, and they’ve become more common in the 21st century—particularly with book adaptations like Harry Potter, Twilight, and The Hunger Games. In …