Cast
Will Ferrell as Brennan Huff
Will Ferrell has said that Brennan is one of his all time favourite characters to play because there were virtually no limits on how far he could take the comedy. He and director Adam McKay have a long creative partnership and a lot of the funniest moments in the film came from improvisation on the day rather than what was written in the script. Ferrell loved playing someone with zero self awareness who is completely convinced that everything he does is completely normal and reasonable. He has talked about how physically demanding the role was because so much of the comedy relies on total commitment to the bit no matter how ridiculous it gets, and Ferrell throws himself into every scene without holding anything back.
John C. Reilly as Dale Doback
John C. Reilly has described Step Brothers as one of the most fun filming experiences of his career. He and Ferrell had worked together before and said that their friendship in real life made the brotherly dynamic between Dale and Brennan feel completely natural and genuine. Reilly loved that Dale is simultaneously the most childish and the most weirdly loyal character in the film, someone who would do absolutely anything for the people he cares about even if his methods are completely unhinged. He has spoken about how much of the film was improvised and how liberating it was to work in an environment where trying something completely unexpected was always encouraged.
Mary Steenburgen as Nancy Huff
Mary Steenburgen brought a lovely warmth to Nancy that grounded the film whenever things got completely out of control. She has talked about how important it was to play Nancy as a real person rather than just a comedic prop, someone who genuinely loves her son but is also completely exhausted by him. Steenburgen said working with Ferrell and Reilly was like trying to keep a straight face in the middle of a tornado and that she genuinely broke character laughing more times than she could count. Her chemistry with Richard Jenkins also gave the film a surprisingly sweet romantic subplot that made the whole story feel more complete.
Richard Jenkins as Robert Doback
Richard Jenkins is primarily known for serious dramatic roles so playing Robert Doback was a real departure for him and he absolutely nailed it. He has said he approached Robert completely seriously, treating him as a real frustrated father rather than playing it for laughs, which ended up making his scenes even funnier. Jenkins loved the dynamic between Robert and Nancy and said finding the genuine affection between two people who are completely overwhelmed by their adult children gave the film a real emotional core underneath all the chaos. His delivery of some of the film’s most exasperated lines became some of the most quoted moments in the whole movie.