The first time we see Rob and Laura Petrie onscreen together, it's about six minutes into "The Sick Boy and the Sitter," the first official episode of The Dick Van Dyke Show. "Hi, honey," Rob calls, finding Laura in the kitchen and giving her a quick kiss before asking, "How's your white satin evening gown?" Laura replies, "Fine, how's your red flannel bathrobe?" Rob makes a face while his lady's joke lands, then Laura laughs, "What kinda greeting is that?"

Well, it's the kind of greeting you give when it turns out you're about to become one of TV's most beloved couples. Like the Ricardos before them, the Petries had their own dynamic, built on a mix of affectionate sweetness and hilarious physical humor. And according to both stars Dick Van Dyke and Mary Tyler Moore, this chemistry between the characters took hardly any work at all. Both insisted instead it was instantaneous.

Moore told the Archive of American Television: "He’s a nice guy, I think I’m a nice lady, and we just liked each other right from the beginning." Van Dyke sounded similar in his own interview: "You could see the beginnings of it, because by the time the week was up and we were in front of the audience, we knew we just had something going.” In fact, Van Dyke goes even further, saying, "It was one of the few times in my life I said, ‘This is very good.’"

"Very good," it was, so much so that the original character Carl Reiner had written for himself in Rob Petrie got tossed out the window as the series creator started slanting his scripts to really help his actors sing in their parts as each half of a married couple. When asked how much of himself he ended up putting into the part of Rob, Van Dyke remembered, "Practically all of me. It was nothing like the character that Carl wrote for himself or that he played in that pilot. To me, Carl Reiner’s greatest talent was writing to people's strengths. We didn’t have to act. He had such an ear for our inflections and our speech patterns, and he wrote them down on paper, so all we had to do was read. Everyone played themselves, including Mary. And it was just that easy and that simple.”

It probably helped that Moore said she was a huge fan of Reiner's (Moore siad, "It was my hero Carl Reiner who was the writer/producer of the show") as well as Van Dyke's. In fact, before she got cast on the show, she remembered playing all the songs from Van Dyke's hugely successful musical Bye Bye Birdie "endlessly." Moore explained why she was so impressed with Van Dyke:

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"He was a dancer, self-taught. And he was so good-looking. There was just right away a sense of being very happy, very safe in the talent that he shared with me and very comfortable in the humor that we shared and an appreciation for each other’s gifts.”

Van Dyke agreed with his costar, who he commended as an incredibly quick learner: "It was just fascinating to watch Mary Tyler Moore grasp it, just grasp it so quickly. Right from the beginning, she saw what was happening and played off me.”

In the end, Moore beat out what she claimed was 75 other girls to get the part of Laura Petrie, and it only took a tiny fib about her age to land the role. She was born in 1936 and Van Dyke in 1925, and back in the late 1950s and early 1960s, a 10-year age difference between husband and wife was not common, especially not on TV. So she aged herself a year to get within that 10-year window, and every fan of Rob and Laura Petrie has been grateful ever since. Moore described the feeling she got after her final audition: "Afterwards, I just had this pretty sure feeling that everybody was pleased. And that I was in fact possibly now on my way.”

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