Monica Potter

[Spoiler alert: The following reveals major plot points from Tuesday's episode of Parenthood.  Read at your own risk.]

A son with Asperger's, money troubles, an unexpected pregnancy. Like almost every member of the Braverman clan, Parenthood's Kristina (Monica Potter) has been put through the wringer. So when it came time to start work on Season 4 of the NBC family drama (Tuesdays at 10/9c), Potter had a gut instinct for what should come next.

"A lot of women that I know deal with breast cancer — a lot of close friends actually — and I had e-mailed [series creator and executive producer] Jason Katims before the season started and I said, 'What if Kristina develops breast cancer,'" Potter tells TVGuide.com. "I think it's a really timely issue."

Little did Potter know when she pressed send that Katims — inspired by his wife's own battle with the disease years earlier — had just begun plotting the exact same story line in the writers' room. "It was this wild coincidence that that happened, but it was also very encouraging," Katims says. "This is obviously a very difficult story that has very challenging and emotional elements. So the idea that — not even hearing that it was something that we wanted to do —she was interested was very exciting to me. Clearly this was something that she was ready to dig into."

However, Katims said his leading lady had one caveat: "She said, 'I don't want to cry in every scene.'"

It seems an unusual request, especially for a series notorious for making viewers reach for the tissues week after week. But if the closing act of Tuesday's episode was any indication, the Bravermans are going to need to stock up on Kleenex.

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For a show that's never shied away from heavy subject matter —  race relations, religion, adoption, infidelity, and Asperger's have all been put under the microscope — Katims admits he was unsure "whether or not it was a road that I wanted to go down."

"My wife has gone through breast cancer so I lived through it with her," the Emmy winner says. "Part of it was for the personal reason of, 'Do I want to go there?' and the other hesitation was I didn't want to do it if it was going to be too depressing or be too heavy."

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It was another story line mined from Katims' personal life — Kristina and Adam's son, Max, suffers from Asperger's just like Katims' own son — that convinced him to move forward. "That was a story that felt, frankly, more challenging than this one," Katims says. "Having been able to tell that story now going on four seasons of the show, it gave me the confidence to feel that we could tell this story in a way that will hopefully feel real and that people who have either gone through it or know people who have gone through it will think we did a good job."

In addition to hiring an oncologist to check the accuracy of the scripts, Katims says his wife usually answers questions and has been supportive of the art-imitates-life storyline. "She's unfortunately used to it with me. We'll be watching episodes of the show and at certain points; she'll just turn her head to me and look at me like, 'Really? So you just use everything,'" Katims says of his wife, who has been in remission for two years. "She's very much an inspiration to me. ... She's been very encouraging because she also feels it's an important story to tell."

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Katims was also swayed to explore the storyline because he knew Potter would be able to find the necessary lighter moments in Kristina's bleak circumstances. "Monica is not only such a wonderful dramatic actress, she is also such an incredible comedienne," he says. "One of the things that was important to us was that we would find not only the hopeful moments but the humor."

Potter is optimistic fans will not only be able to find upcoming moments of Kristina's struggle funny, but also therapeutic. "The first two episodes were sort of a punch in the stomach for me to read and I think a lot of our fans will find it to be a little startling," she says. "But also, as the season goes, I think it will be very cathartic."

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So how will the diagnosis impact Kristina, her husband, Adam (Peter Krause), and their kids long-term? "It will run the gamut of emotions of how it affects them," Katims says. "There's a part of it that's very scary and they will be scared. There's also the reality of as you go through this, life is also going on. ... They have a daughter who just left for college, they have a baby, they have a son."

However, Katims admits there is no short answer for what's ahead for Kristina and the rest of the  Braverman clan. "I wish there was .... but I think what makes [this portrayal] different is that we are hopefully going to try to reflect, in a very whole way, what it's like to go through this experience," he says. "I feel like this is a story that is going to go on the entire season, and even beyond."

Watch our interview with Potter on the set of Parenthood to see why she felt strongly about the storyline, how Kristina will deal and when she'll break it to the rest of the family:

Parenthood airs Tuesdays at 10/9c on NBC.