Talking to MTV News, the actor - who plays Dicky alongside Mark Wahlberg's Micky - admitted that he struggled with the men to assure that their "rollercoaster" story was presented perfectly.
"[We said] 'Look, there's no story here unless we show the dregs. You've got to show the lows'," he explained.
"It's the rollercoaster of their life that makes it a fascinating story. Each one individually doesn't make a movie, but you combine the two brothers, and there's a fascinating movie."
Bale also revealed that the family had particular ideas on how the film should be shot, sometimes causing explosive disagreements on set.
"We [had] to show that side of it, and also condensing a life into two hours, you're taking some license. Initially, there were a lot of problems. Dicky would be saying, 'That's not how it went down. I said this not that' and 'He wasn't there at that point. He was over here'," he recalled.
"[We told him] 'Right, but we've had to kind of blend these two scenes, because otherwise this movie is going to be years long'. So he came to understand that, but there were a couple of moments where I had to say, 'Dicky, don't go punch [director] David [O Russell] now. Don't go punch him. It's all right, count to ten, let's figure it out.' And I'm sure David and Mark had to stop him from punching me and stuff."
The Fighter opens in US cinemas today and in the UK on February 4, 2011.