“The close relationship between Fili and Kili is crucial to understanding their characters and is informed by Dean’s rapport with Aidan: ‘The brothers are really close and do everything together: where one goes, the other goes, always running off ahead and doing stuff, looking round corners, checking things out. But although Fili can be a bit reckless at times, he is the more responsible of the two and feels protective of his younger brother. The great thing was that as soon as Aidan and I met we clicked; we instantly knew we were going to get along and the more time we spend together, the more we’ve developed a brotherly bond that’s helped us figure out the dynamic of our characters.’”
— Dean O’Gorman, The Hobbit: An Unexpected Journey Official Movie Guide