Marvel Cinematic Universe fans are anxiously waiting to see what happens in the Avengers franchise, and that’s all thanks to the brilliant Infinity War cliffhanger. Beloved Marvel characters, including many of the heroes, turned to ashes soon after Thanos snapped his fingers, killing off half of the population in the known universe.

Since April, we’ve been collecting plenty of evidence that suggests the deaths will be undone in Avengers 4 and that time-travel will play a big role in thwarting Thanos’ plans. After the movie was released, execs who worked on the film including the writers and directors said that some deaths are final though, teasing that other shocking events will follow. But it turns out that even the cast and crew of Avengers 4 don’t yet know how the movie will end, because it hasn’t yet been decided.

So says the biggest leaker in the Avengers roster, Mark Ruffalo. Tom Holland is a close second, but it’s Ruffalo who almost spoiled the ending of Infinity War while promoting the film.

This time around, Ruffalo sat down with the folks of The Marvelist to chat about how he got the Hulk role, what this Hulk journey has meant to him, and how the character evolved. Ruffalo also explained why the Hulk refused to show up in Infinity War (via ComicBook):

We went back and forth a lot on how to end the movie with Banner, and do we repeat the Hulk coming at the last minute or do we try something new? And I think at that point we were all thirsting to have Banner be his own hero for once. There’s a conflict brewing between banner and Hulk that’s been going on since the beginning, and it all came out of this question that Joss Whedon asked me when Hulk gets the fairy dust from Scarlet Witch sprinkled on him in Avengers 2. Joss asked ‘What is Hulk afraid of?’ And that was a hard thing for me to answer, because what is the strongest, fiercest thing in the universe afraid of? What could he possibly? And then I realized its Banner. The only thing Hulk is afraid of is Banner. And so that’s become something we’ve been riffing on since Avengers 2. We played with a lot in Ragnarok, and it continues to be teased out in Infinity War 1 and Infinity War 2.

The actor also teased what he’d like to see going forward for these two characters:

I can’t really talk about it, what I want, because I’ve had so much a hand in where it’s going, my own little hand. But I will say that I want to see this conflict carried out and see where that takes us and see, can they come to terms with it? Do they get a moment? I always thought it would be great to see them in some sort of subspace where they get to battle it out with Banner’s brains as some sort of his own superpower, like psych weaponry or psi weaponry against Hulk’s brute strength and have these two characters battle it out. I always thought that would be the ultimate comic book ending or something, opening to these characters.

He then explained that they’re doing reshoots for Avengers 4 starting September, something we already knew, and that they’re going to “finish the movie.” Not even the Russo brothers, who directed both Infinity War films, know exactly how the film will end.

We were under the impression that shooting for the film had finished last year, which meant pressure from the public following Infinity War wouldn’t interfere with what was planned for Avengers 4. Later we learned the Russos hope to finish the film by March, but we did not know reshoots were in order. Then we heard that reshoots were in the works, and Black Panther might get plenty of additional scenes.

Ruffalo explained to The Marvelists what’s next for the cast (via DigitalSpy):

We’re doing reshoots starting in September, and then we’ll go back into the international tour, we’ll go on tour. Then you guys will get the second installment. Which we don’t even know what it’s gonna be yet. We’re not just doing reshoots. We’re going to finish the movie, which we really didn’t get to finish totally when we left it last year. I don’t even know that they really know exactly [how the film will end]. Some of it is happening while we’re there. It’s pretty amazing. And we’ll shoot some stuff and a few days later come back and reshoot it ’cause we wanna take it in another direction. It’s a very living organism; even as we approach it being a locked picture, we’re still working on it.

The star also said it’s common practice for the Avengers actors to receive dummy scripts to keep the film’s secrets. A different report did say that Benedict Cumberbatch, who plays Doctor Strange, is the only one who had read the entire script. That said, Ruffalo did not let any secrets slip out, acknowledging that he and Holland may be likely sources of leaks. You can listen to the full episode at this link, with the Ruffalo interview taking place in the second half.