The Russos confirm they're retitling the movies.

When Marvel announced Avengers: Infinity War I and II people assumed that these films would tell one long story that would be cut in the middle, in the tradition of recent YA adaptations going from trilogies to quadrilogies. I had started hearing a couple of months ago that this wasn't the case, that each film was very much its own movie, and that Infinity War I would have a definitive, complete ending. No cliffhangers, no 'to be continued.' It would be a whole film.

“It is misleading,” Anthony Russo told Uproxx in a new interview.

Joe Russo added, “The intention is we will change it, we just haven’t come up with the titles yet. But, yes, we will change it. And, yes, that is a scoop: we will retitle them.”

So Infinity War is not just a placeholder name until they come up with something better. Infinity War I, I understand, is very Thanos heavy, setting up not only the character (which previous films have failed to do) but also getting him the Infinity Stones (which previous films have failed to do). Infinity War II is going to be the big action finale, with just about every Marvel Cinematic Universe hero showing up. Having seen how well the Russos handled a bunch of heroes brawling in Civil War I couldn't be more excited to see them up the ante and bring in a couple dozen more characters. 

Since even the Russos don't know the new titles we have a good opportunity to get nerdy and fan-title these films. What if the first film is called Thanos Quest and the second film Infinity War? That's my off-the-top-of-my-head pitch. What would you title these two movies about which you know nothing whatsoever?