The actor breaks down his character's big Tuesday episode.
Spoiler alert! Do not proceed if you have not watched Tuesday's episode of This Is Us.
This Is Us continued its farewell tour Tuesday, kickstarting its final trilogy of episodes focused on the Big Three. The first of three installments, "The Guitar Man" (directed by series star Milo Ventimiglia), centered the action on Kevin as he took his twins to the cabin in an effort to prove himself as a father. There, while actively working through the construction and chart the progress of making Jack's dream home for his family a reality -- with the help of Cassidy (Jennifer Morrison) and Nicky (Griffin Dunne) -- he found himself faced with an unexpected crisis. Not of his own, but Cassidy's.
As he learned in the hospital room following Cassidy's near-fatal accident, the war veteran often went on nightly drives when her mind couldn't settle. And after experiencing a nice family-like atmosphere earlier in the evening, she left to go on one of her evening drives to clear her thoughts. But this time was different. Feeling emotionally, mentally and physically tired, she reached the point of exhaustion where she felt she couldn't go on and, devastatingly, was ready to go. While Kevin would've had a very different reaction had he been faced with this situation in season 1 (or perhaps he would've been in Cassidy's shoes), he -- along with Nicky -- was there to offer support for Cassidy and get her back on her feet.
"I think we've earned it," Justin Hartley told ET over the phone when asked about Kevin's growth over six seasons. "The cool thing about the show and Kevin's character is that we saw him go through addiction, where it was crushing him; it was burying him. And the writers did such a good job of not turning it into one episode about a guy who overcomes addiction. They very much made it part of his fabric. It never leaves, so he's always carrying that with him. And, in a way, it's made him stronger. I think the things that he cared about before were things that he thought other people thought he should care about and now he cares about things that really matter to him. That's a major difference. It just took him a while to get there."
The actor noted that when the emotional hospital scene between Kevin, Cassidy and Nicky comes, Kevin has finally gotten "to that place where he wants to help."
"He's a good guy, and he just simply doesn't know what to do. There's been this thing with Kevin, I think, from the very beginning where he feels like he has to say something or he feels like he has to act or he feels like he has to do something or he feels like he has to help. And the interesting thing about that, and I've always thought about him as an actor, is he hears, 'Action.' And you have this impulse to do something because someone called, 'Action,'" Hartley broke down.
"In that speech that he had in the hospital in [the] episode, and what Nicky tells him as well, sometimes you just have to be sitting there and the other person has to know that you're just sitting there and you're with them," he explained. "There's comfort in that. When people are going through something, if you just sit down next to them, you just look at them. If someone's miserable, there's nothing you can do to help because the arm is broken or the rib is broken or whatever and you have to sit there and wait for it to heal. If you're sitting with someone during their pain, sometimes that's all they need and that's all you should be doing. So this need to say something all the time and do something and fix it, that's gotten in his way. I think he's finally realizing that's not always what you need to be doing."
"In this episode, throughout the whole episode, he very much is the person that is the decider, right? He becomes the president of his little nation and he's the guy that makes all the decisions. And if he makes the wrong decision, there's consequences," Hartley said. "I just think that his anxiety level goes down when he realizes that the worst thing that could possibly happen if your heart's in the right place is not that bad. So I think that gives him peace. And also the fact that he can be there for people. That's kind of nice. That's his job and that's what he's really good at. He's figured out what he's really good at, and it is being there for people and taking care of others. And obviously he can't do that unless he takes care of himself. It's just a massive growth, maturation thing that happens in [the] episode -- from the beginning to the end."
As Kevin realizes his place, his search to fill the void left behind by his father is finally being filled. Sure, he hasn't yet found his "true love" like he had previously envisioned, but as Hartley says, he's found things and people to gradually fill that empty space.
"I think that chasing that dream, it's the same thing as chasing stock or you're playing blackjack and you've got 18 to stay. He also has kids, so that's become his new focus. He's got the charity and a lot of things have filled that empty hole that was something that he just couldn't fill before, so he was on this business man on a mission, searching for the thing that was up to someone else," Hartley said. "He's realized that he's now in control of his own life. He's got kids, he's got the nonprofit, he's got his family and he's got his life experiences. I think that's enough for him. And oftentimes, when you find that for yourself, it opens you up to be available to maybe meet the person that you were not expecting to meet. I think that's where he is."
Hartley hopes the door is still open for Kevin to find his person. "I hope so, yeah. He's not that dead," he joked. "We got a few good years left in him."
The actor also steps behind the camera for episode 10 of the season, a Randall-centric episode airing March 29 that closes out the series' last Big Three trilogy. The hour follows Randall and Rebecca as they go on a road trip to reflect on their past.
"I would say that entire episode, circle that one because that'll take you on a ride for sure," Hartley teased, promising it's "a good one." "That was a story that was told by our beautiful writers that, while I was shooting it, you're watching these scenes and you're trying to hold it together. That's a big one."
"It's always fun to direct these wonderful actors and they give such great performances, and the writing is so good," he said of directing Sterling K. Brown and his co-stars. "I love working with everybody, so there's the benefit of that, but also just being able to dial into one particular character is pretty special as well."
This Is Us airs Tuesdays at 9 p.m. ET/PT on NBC.
To stay up to date on breaking TV news, sign up for ET's daily newsletter.