[Warning: The following contains spoilers for the Season 4 premiere of This Is Us. Read at your own risk]

It's a new season of This Is Us, which means that there's another time twist. The Season 4 premiere introduced several characters who will have major impacts on the Pearson family story. Most of the new faces are people we've never met before, but it turns out that the blind musician — played by newcomer Blake Stadnik — who we meet at the beginning of the episode is a grown-up version of a character we know very well: He's Kate (Chrissy Metz) and Toby's (Chris Sullivan) son, Jack. The flash-forward of Jack at the end of the episode revealed that music stayed in the Pearson family, showing Jack performing for a sold-out crowd.

In the present timeline, Kate and Toby find out that their newborn son isn't responding to visual cues. Elsewhere, we are introduced to Jennifer Morrison's character, a marine who is telling her story at a veterans' support group when Nicky (Griffin Dunne) throws a chair through the window. And When They See Us' Asante Blackk plays Malik, a young man who becomes enamored of Deja (Lyric Ross) after Randall (Sterling K. Brown) and Beth (Susan Kelechi Watson) move their family to Philadelphia.

The beginning of Season 4 marks the halfway point in the story that creator Dan Fogelman mapped out for the Pearson family when he originally pitched the series to NBC. Introducing these new characters was part of his master plan, he said, and the episode was specifically designed to give fans an intimate look at these people before they intersect with the Pearson family we love so much. Fogelman chatted with journalists ahead of the game-changing premiere to break down what that big time-jump means and where the rest of Season 4 is going.

Is the show planning to return to see Jack as an adult again this season, or was this more of a one-off?
Dan Fogelman: I'm kind of in love with the actor (Blake Stadnik) that we found. It's a difficult time period to go back to all the time because it's pretty deep in the future and it presents production challenges. But we do plan on returning to it. We have a plan, basically, that I can't get into too much. He will be returned to. Right now, we're telling stories in the beginning half of the season that focus more on the present-day stories. It is a place that we're heading to again, multiple times, especially because we had an experience with the young man who was acting on camera literally for the first time in his entire life that was so rewarding. We fell so in love with the actor. Sometimes those things happen, and the parts get even bigger than you planned on making them.

What motivated the decision for Jack to have blindness?
Fogelman
: We've always known, for a while now, that Kate's son was going to be born prematurely, and blindness, retinopathy, is a very common thing that would come from that. We've always known that's where we were heading. ... [It was] always being part of the character and the story that we were telling, if that makes any sense. Certainly, music has always been a big part of this family's story, generationally. Obviously, it continues on down the line.

Everyone is very interested in going back to the "her" story, especially now that we know it's Rebecca. Can you talk about when we'll get back to that part of the mystery and how much do you plan to reveal this season?
Fogelman: We're going to give a lot of answers there this season...especially by the end of the first half of the season. By having shown the full end game without sharing all of the details, we've set ourselves up to start the slow process of telling the story of how we get there. This is one that will be anchored in this season, especially in the first half or two-thirds of this season, to set us up for some bigger leaps into the future as we get a little deeper into this season and next. The series was always broken down into two three-season plans. Obviously, we kind of know where our endgame is, and now it's kind of the fun of filling in the holes.

Chrissy Metz and Chris Sullivan, <em>This Is Us</em>Chrissy Metz and Chris Sullivan, This Is Us

Does adult Jack take us further than where you are with the Rebecca scenes?
Fogelman: It does. Jack would be approximately 12 years old in the [Rebecca] period. It would be in his teens or pre-teens. What you're seeing [in the season premiere] is about 10 years after that.

So even though you've said that your endgame is in that Rebecca future, we are going to see other jumps in the future that aren't part of that endgame?
Fogelman: Yes. When we talk about the kind of endgame of that future storyline that's already been established with her, it's kind of where the story of our Pearson family, the immediate family, kind of heads toward. It does not mean that it's the endgame in terms of timelines.

You introduced some new faces. Are we going to see them again? Will we be going back to Jennifer Morrison's character, for instance?
Fogelman: These new characters are framed as characters that are going to have massive impacts on the main family's lives. They are massive parts of this season. They are not just in a one-off episode as a person who was in the room when Nicky threw a chair through the window or met Deja at a party. It's going to go far beyond that. It's going to be a slow build, and part of the intent here was to establish these characters so that you met them kind of pure and outside of the purview of the Pearson family. You really are inside of these characters' stories and you know them. Now we slowly start building them into [the Pearsons'] world and they affect and really change, things. Jennifer, Asante, and [Omar Epps], they are huge parts of the storyline this season.

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Why did now feel like the right time to expand the world? Was it something you felt that you had to do because it was Season 4?
Fogelman: It was always part of the intent. We had always talked about wanting to do this episode to start a season, with these characters that come in and kind of change the course of people's lives. We're just writing a show about the collective us as people and different types of people from different walks of life. I've always been fascinated with the idea that we can go about our lives for 10, 20, 30, 40 years, and there are random people that you'll see at a bar, meet them at a coffee shop, and you'll end up marrying that person or working with that person for the next 30 years...I've always wanted this [episode], in particular, to go in the middle of the series so we meet these new people that haven't been part of our story yet, really spend the time inside of their worlds a little bit, and then say, "Oh, okay. That's going to be an interesting or strange person to intersect with one of my favorite characters."

It's not just to add characters to the story. These stories are really about Randall, Kevin, Kate, Jack, and Rebecca. These characters are servicing them while really rounding out our world. I think by the end of the season, you'll really see the effect that these new characters have had on the people that we really know. This is a starting point.

It was a really nice surprise to see Tim Matheson being an obstacle for Jack in the flashbacks.
Fogelman: That's always been a fun part of Jack. When we started the series, people were always asking what's going to happen after you show how Jack dies. I always know there was going to be a lot more story to tell because I thought it was interesting storytelling device, and a challenging one, to get invested in storylines that happen before the ending that we know. I find it wildly visceral and engaging to see Jack and Rebecca's love story, for instance, with Tim's character as an obstacle. How did they overcome that? Did they overcome that? We've always had a plan for it, but you haven't seen Rebecca's father in their lives ever in the first three seasons of the show. Elizabeth Perkins, as her mother, has played [a role]. Where has her father [been]? He's been referenced a few times, but is there estrangement over the course of their relationship? I find that, just like Vietnam, such an interesting place to revisit with Jack. We know how ended, but how he got there is such an interesting thing for us as writers.

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In previous seasons, the flashbacks with Jack and Rebecca have set up or paralleled what's going on with the present or future storylines. What is it about the early stages of their relationship that is going to match up with the stories you're telling in the present day? Fogelman: It's something we talk about a lot. Our typical structure is more like the second episode of this season where you have a [present-day] storyline, and the storylines of Jack and Rebecca in the past — and in particular the Big 3 — comments upon or informs the story of the Big 3 in the present.

Whenever we go to Jack and Rebecca before they had children — and that can be in this time period or even when they're just kind of pregnant — our ties tend to be more thematic...Those always become really challenging and really exciting episodes for us because that connection is more generational and thematic than individualized and specific. ... This is an unusually structured episode, but as you get to the end you realize that Rebecca's hopes and dreams of being a musician spread to her grandchild.

In later episodes when we return to [Jack and Rebecca's dating storyline], it's very golf-focused. It picks up with Jack's relationship to his soon-to-be father-in-law, and we see what happens when he takes him to a country club to learn a sport that Jack doesn't know and is embarrassed by. It plays in generationally how fathers teach their sons golf and how it carries, so it's only like three storylines. It's Jack and his father-in-law. It's Jack and Randall when he's 12 years old. Then it's Randall as a grown man, playing golf to woo people in his political space. But really it's about how, generationally, golf trickles down. We play with it in a bunch of different ways, is the long-winded answer.

This Is Us continues Tuesdays at 9/8c on NBC.