The actor enjoyed huge box office success earlier this summer part of the ensemble cast of the Marvel movie - which went on to gross over $1 billion and become the third biggest movie of all time.
But Renner reveals that the character was taken down a different path than he originally expected and he wasn't able to develop Hawkeye as he would have liked.
Speaking to the Los Angeles Times the actor said: "At the end of the day, 90% of the movie, I'm not the character I signed on to play. I'm literally in there for two minutes, and then all of a sudden...
"All I could really work on was the physical part of it all, because that didn't change. That was just the biggest challenge to overcome in playing the guy.
"I was limited, you know what I mean? I was a terminator in a way. So yeah, fun stunts.
"But is there any sort of emotional content or thought process? No. That doesn't exist in that time [that he's hypnotized]. It happens to be for most of the movie.
A second Avengers movie was announced last week - however it is not yet clear who will be returning.
But Renner is back on the big screen this week as he takes on the role of Aaron Cross in The Bourne Legacy.
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