Avengers 4: 8 Major Plot Predictions

In the past, Mark Ruffalo has stated that Thor: Ragnarok was the start of a three-film arc for Bruce Banner/Hulk, with Infinity War and Avengers 4 serving as parts two and three.

And now that we have the first two-thirds of this overarching story to digest, it's much easier to guess where it might be leading.

In Ragnarok, Banner had been stuck as Hulk for around two years, before turning back into his human form after seeing a recording of Natasha. For the rest of the movie, he's reluctant to go green again, out of fear that the Hulk might become his permanent form.

Ultimately, he does transform into the Hulk, to help save the people of Asgard. But this change isn't permanent at all, and Infinity War starts with him crash-landing on Earth (after being beaten down by Thanos) while turning back into Banner.

And for the rest of the movie, Hulk is never seen again. Banner tries to coax him out, but the "other guy" just isn't having it. The movie doesn't explicitly state why this is, but it's assumed that Hulk is too afraid to face Thanos once again.

Ragnarok and Infinity War are about Hulk's/Banner's distrust and fear of one another. In Ragnarok, Hulk initially doesn't want to become human, and later, Banner is scared of becoming Hulk. In Infinity War, Hulk doesn't want to come out at all. The two personalities aren't working in tandem, or helping each other; they're both trapped, and feel like they're being held at each other's mercy.

And so, Avengers 4 will likely conclude with Hulk and Banner essentially becoming one, learning to work together for the greater good. Banner needs a huge, important "Hulking out" moment to solidify this, and what better way to portray that than by having him save Natasha - the woman he loves - from Thanos?

This way, Hulk gets to face his fear of the Mad Titan, and Natasha - who helped Hulk transform into Banner midway through Ragnarok - gets to help Banner transform into Hulk.