Jamie Dornan on his relationship with Dakota Johnson

Despite the fact that Christian Grey (Dornan) and Anastasia Steele (Johnson) have intense sexual chemistry on-screen, their real-life relationship is quite the opposite. 

"This is going to sound bad, but it's almost like brother, sister," Dornan, 35, told ET.

"Because I am married, and she's had a lot of relationships in the time that we've known each other. You just have this sort of mutual love and respect for each other, and I feel like we know each other so well, and intimately."

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The Fifty Shades stars recently spoke to WHO about their sex scenes and the sex toys Christian uses.

"We had a man, whose title was kink adviser, on the set," he told WHO. "He was able to fill me in on a lot of the apparatus so I would look like I knew what  I was doing. "

For more from Dornan and Johnson's exclusive interview with WHO, pick up a copy of the latest issue on newsstands now.