Don Cheadle's character James 'Rhodey' Rhodes plays a "pivotal" role in 'Captain America: Civil War'.
The 51-year-old actor is reprising his role as Lieutenant Colonel Rhodes - aka War Machine - in the upcoming Marvel Studios sequel and unlike in other movies he is at the forefront of the plot and the action.
Speaking from the Sundance Film Festival, he said: "I never know what it's going to be and they keep their cards very close to their breast with Marvel. I never know where the character's going to go, but he's become more and more and in the next one, you'll see that what happens to Rhodey is a little bit more intense and pivotal to what happens in the rest of the stories."
Cheadle has played Tony Stark's pal in two 'Iron Man' sequels and in 'Avengers: Age of Ultron', although he did not feature prominently in the second superhero ensemble.
The star enjoys being part of the Marvel cinematic universe although he admits it can frustrating acting with green screens all the time.
He said: "I ultimately like it when we're there and I'm working with other actors and it's fun, but it can be very tedious. A lot of time you're looking at a green screen and a tennis ball on a C-stand. But you just give over to the elements and go, 'Oh these are the toys and I'm playing with the biggest and best toys,' and we're flying around and doing stuff that if I was 10 years old, I would be having the greatest time in my life!"
The film will be centred around a feud between Iron Man (Robert Downey Jr.) and Captain America (Chris Evans) and as well as a number of Avengers returning the film will also feature first time appearances in the franchise from characters Black Panther (Chadwick Boseman) and Spider-Man (Tom Holland).
'Captain America: Civil War' hits theatres this May 6.