Spoilers ahead for Avengers: Infinity War
When Avengers: Infinity War was originally announced, it was going to be Avengers: Infinity War – Part I and Avengers: Infinity War – Part II. That later changed when it was decided that Avengers 4 would be released as its own movie rather than dubbing it the second part of one big story. Arguably this was just a savvy business decision after the recent multi-part movie, The Hunger Games: Mockingjay, had its second part bring in less money that the preceding installment. Either way, Infinity War exists in that uncommon situation where it’s meant to be a film that can stand on its own, but also have a cliffhanger showing that the story we just watched isn’t finished yet.
Of course, that’s nothing new to movies. Even setting aside early serials, recent blockbusters haven’t shied away from a multi-part saga. The Lord of the Rings and The Hobbit all have a continuing journey that doesn’t resolve until the last installment. The Star Wars saga is ongoing and no one bats an eye when The Last Jedi concludes with the resistance in rebuilding mode and the First Order still standing. When Marty McFly rounds the corner in Back to the Future: Part II, we know that we’ll need to get him back to the 1985 in a route that will somehow take him through the Wild West. The story isn’t finished, but audiences don’t feel cheated.
And the reason they don’t feel cheated is that it’s possible to tell an ongoing story and a complete story. Those examples I just provided all stand on their own. They have character arcs and rising and falling action. There’s conflict that’s ongoing, but there’s also conflict that gets resolved. In The Lord of the Rings: The Fellowship of the Ring, Frodo has to learn that to be a ringbearer is to be alone. The Fellowship cannot continue because The One Ring will tear them apart. Frodo goes from someone who has to lean on a group of people to having to just lean on Samwise. Additionally, Aragorn has to learn that he’s strong enough to resist the One Ring and that he doesn’t have the same weakness as his ancestors. And characters like Gandalf and Boromir die sacrificing themselves for the good of the mission. There’s real stakes and real change even though the story—getting the ring to Mount Doom—continues.
Compare that to Infinity War where the world has certainly changed (and set aside that it will probably be undone since these movies can’t inhabit a universe where half the population suddenly died), but the characters have remained the same. Thanos is the protagonist on a “hero’s journey” of sorts, but it’s a journey that doesn’t really challenge him or force him to change. At no point does Thanos ever have to reconsider his actions. His “moment of truth” is killing Gamora, and even that’s not much of a plot point because a serious connection was never built between the two characters. We know he cares about her, but he has to care more about his mission, so her death is automatically diminished in comparison to Thanos’ goal.