Mark Ruffalo Told Josh Brolin He Would Be a Fool Not to be in 'Avengers: Infinity War'

After years of teasing, actor Josh Brolin will finally make his impact on the Marvel Cinematic Universe with the premiere of Avengers: Infinity War.

But Brolin wasn't a lock to join the Marvel Studios family, and only did so after he received some counsel from Mark Ruffalo. The Hulk actor revealed the story while appearing with cast members on Jimmy Kimmel Live to promote the new film.

"I said, you'd be a fool not to be in this movie," Ruffalo revealed.

Brolin first appeared as Thanos for a brief scene in Guardians of the Galaxy, and once again in the post-credits stinger for Avengers: Age of Ultron. But this latest film will be his first substantial role in the MCU, and directors Anthony and Joseph Russo have often referred to Thanos as the main character.

"We always try to bring in topical themes into these films because they function on such a wide scale that we really want the audience to feel a sense of immediacy in their own lives about what they're watching," Joe said to Telegraph India. "Every villain is a hero in his own story and believes that what they're doing is right. They're just in conflict with the rest of the world. Thanos happens to believe that what he is doing is right, and he behaves nobly towards that goal. But he will not stop until he achieves the goal because he believes that there is weakness that stands between him and the completion of the goal."

Screenwriters Christopher Markus and Stephen McFeely said they tackled the project as "a Thanos movie," reinforcing what the directors said.

"This is about the culmination of the Marvel Cinematic Universe," McFeely said to ComicBook.com. "This is about everyone getting together, or trying their hardest to get together, to fight a guy named Thanos. We've been teasing Thanos for many movies in 30 second clips, so hopefully all the lead up will allow us to really go to town with him and make him a villain that requires this epic level of storytelling," McFeely went on. "That is the word I would use most often. It's ridiculously big."

And even though Brolin will also be playing Cable in this summer's Deadpool 2, the actor admitted he prefers playing the Mad Titan.

"Look, I really like doing Cable, and it's practical," Brolin told Total Film. "But I think if I was to have a preference, it'd be Thanos, just because my expectation was pretty low, given that I just thought I was a prop. And it was quite the opposite, having seen enough of the movie and realised how cutting edge this technical process is, y'know? I was watching me. I was watching every twitch, every blink. I was watching my eyes. My actions. I was living through my intentions."

Fans will get to see Thanos' star turn in Avengers: Infinity War, premiering this Friday.