The journey is just beginning on This Is Us.



NBC’s heartwarming family drama premiered last week, and struck a chord with America before revealing a major twist in its final moments: Rebecca and Jack’s (Mandy Moore and Milo Ventimiglia) story is being told in the past and their three children -- Kate (Chrissy Metz), Kevin (Justin Hartley) and Randall (Sterling K. Brown), the latter of whom they adopted -- are living in the present.

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The surprising twist was intentionally kept under wraps, prompting a visceral, real-time reaction among viewers. It paid off. More than 10 million people tuned into last Tuesday’s debut, making it the first breakout hit of the young television season. For creator Dan Fogelman, the work is just beginning.

“It’s a good day,” he told ET the day after the premiere, admitting the months of secret-keeping weighed on him “a little bit.” “The next three episodes are really, really strong and there’s an emotional response to the characters and the material. Hopefully, in its own unique way, that can draw people in a different way to TV, like the way I was drawn to it as a little kid.”

As This Is Us prepares to launch its second episode, Fogelman jumped on the phone to chat with ET about the show’s sudden success, keeping up the emotion and where it’s all going next.

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ET: Viewers had an emotional response to the first episode, especially with that gut-wrenching ending. Is that type of response something you’re actively working towards?



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Dan Fogelman: Definitely not. We’re not sitting and going “Let’s try and make this scene emotional or let’s have one emotional [moment] in every act of the show.” It’s really not as calculated as that -- it’d be impossible to do it. I’m constantly surprised as to which of the moments really move me and they’re not the moments that I’d expected. At a certain point a show kind of locks into what it is. I think we’ve done that very early here in our first couple of episodes.



There’s the sense from the premiere that things eventually work out for the family. Is that element of hopefulness something that will continue?



These characters are at a crossroads and they all get these little victories [in the premiere], and life isn’t all like that. Moving into the series, there are darker moments and I think even in the more uncomfortable and complicated moments, people are going to recognize versions of themselves or people they know. If we can make that happen and then also make people laugh and make people get upset with characters and love characters [then we’ve done our job].



It’s been said that each episode will continue to have an “a-ha” moment or an unexpected revelation. How challenging is it to realistically keep that going?



It is very hard. We’re not doing a big, gigantic twist every week; the best way I’ve been able to describe it is if somebody took all your home videos of your life and your childhood, particularly, and your family and mixed them in a bag, things would surprise you: Who is still in the videos five years later, who’s not in the videos, where relationships are years later versus where they are in the beginning. The show will continue to challenge the audience and subvert their expectations a little bit and there will be surprising choices made. Even though the show is [about] seven, eight people, we also want their journeys to feel big -- big feelings about love and life and loss and death and parenting and family and children.

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Now that we know there are two different timelines, how will you balance the storylines? Is what’s established in the first episode the blueprint going forward?



We shake it up quite a bit. Our typical episode is similarly structured to the pilot in that you’ve got these four storylines that you float between. Especially as we go further into the season, we are going to break our pattern a little bit. We might do episodes that focus only on one storyline per episode. The Mandy-Milo storyline will jump around in time so in the first five episodes, you see them eight years in the future, you see them right where they were at the pilot and you see them before they had kids. By the end of the first season, you’ll understand the history of this family but we won’t be telling it all linearly.



Let’s break down what’s in store for each of the characters. First up, Randall. What can you tease about his journey?



As you get to know Randall, Sterling’s character, he’s a guy who’s got it all going. He’s a perfectionist and he takes everything he does very seriously and suddenly there’s this man who’s throwing him off. I just finished watching the fourth episode where he’s really talking to him about [being raised by a white family]: “I will not apologize for the fact that I was raised by white people and I have a father I love, a white father.” We’ve talked with a lot of people about adoption and interracial adoption and he’s dealing a lot of different issues in that regard as well.



How sick is Randall’s biological father, William (Ron Cephas Jones)?



It’s a big part of the second episode, and the third episode of the show is exploring what’s real about William’s health, what’s not real, the suspicions on the family of this man and his reality.

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Are the origins of Kate’s struggles with her weight something that will be explored?



In the opening scene in our second episode you see that this has been a first ballot issue for Kate her entire life since adolescence. At this precise moment in her life, it’s been her lifelong battle and she’s made a choice to attack it in a different way, head-on. It gets a lot of real estate in the early parts of the first season, but we also do a tremendous amount of other stuff with her as the season goes on.



What lies ahead for Kevin in his post-Man-ny career?



Big, big changes for Kevin. Here he’s made this big stand and quit his show and the second episode is very much focused on the real-world aftermath of what’s going to happen now. Katey Sagal plays his agent, a high-powered take on Ari Emanuel, and Brad Garrett plays the president of the network. Kevin has a come-to-Jesus moment where he has to sit down with these people and learn what the reality of quitting a national television show in a public manner [is] -- and it’s not pretty. It leads into a bunch of decisions that completely changes his life and career.



Is there a chance we’ll see all the characters and actors -- specifically Mandy, Milo, Chrissy, Justin and Sterling -- interacting in the same scene in some way?



There are definite incarnations of that. It’s hard to say it without giving too much away in the future, but yes, there are versions of scenes where different actors you wouldn’t expect being together -- certainly a ton with Sterling, Chrissy and Justin together. There are surprises with the parents and different things we do with them, but certainly all the characters engage at certain points.

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Has it been established that Jack is dead in the present day and/or Rebecca is still alive, or is that also its own mystery?



That is not established. That is still [a question]. As of the end of this pilot, there’s been no talk as to where Jack and Rebecca are -- or not.



This Is Us airs Tuesdays at 10 p.m. ET/PT on NBC.