[Warning: The following contains spoilers from Tuesday's episode of This Is Us. Read at your own risk!]

If we could describe Kevin Pearson's (Justin Hartley) journey on This Is Us, it would be growth. The off-the-rails eldest sibling of the Big 3 has found some real stability in his sobriety and is making strides towards having the life Jack (Milo Ventimiglia) would have always wanted for his son. That has never been more evident than in Tuesday's episode of This Is Us, "Hell of a Week Part 2," in which Kevin had multiple opportunities to slip into his self-destructive ways, but managed to stay above it.

The second episode of the Big 3 trilogy brought Kevin back to Pittsburgh for Sophie's (Alexandra Breckenridge) mother's funeral. The tense, emotional occasion proved that there's still a spark between the exes, but Sophie remained faithful to her fiancé and Kevin resisted the urge to push her into breaking that trust. Okay, so he did sleep with Madison (Caitlin Thompson) at the end of the episode, which isn't great considering she's Kate's (Chrissy Metz) best friend — but the two did have a real moment before it was revealed they tumbled into bed together. At the end of the episode, Madison is the No. 1 suspect for who is Kevin's mysterious fiancée revealed in the fall finale back in November, but we can't count Sophie out yet either.

TV Guide hopped on the phone to chat with Hartley about the episode, breaking down all those adorable moments with Sophie, Kevin's journey for the rest of the season, and how Hartley felt stepping behind the camera for Metz's big episode, "Hell of a Week Part 3."

Justin Hartley, <em>This Is Us</em>Justin Hartley, This Is Us

First things first, does Kevin have real feelings for Madison, or was that a rebound after an intense few days with Sophie?
Justin Hartley:
I guess it's kind of a rebound...He had a pretty rough day. He had a rough week, rough weekend. He's had a rough couple of months, rough year. Then he goes over there to spend time with the baby and you know, Madison is there. She's also kind of had a bad year. She's lonely. She's alone. He says the right thing, I think, but it comes from the heart. He says something that he really means, you know. "You should stop looking at it that way. I wish I had that." Then they have that immediate connection. I think it's just two people that were in need of something at that very moment. It was sort of like a perfect storm. Then, of course, there's the aftermath, right? This dude slept with his twin sister's best friend. [Madison] did the same thing, but that's a tough thing. Man, that's maybe not the right move.

Putting the Madison situation aside, does it surprise you that Kevin is the member of the Big 3 that's currently the most put together?
Hartley:
I never really looked at it that way. That's so funny that you said that, but if you really do take [the Madison situation] out, and you think about what this man is doing — he's going to support his ex-wife, this woman that he loves, and she lost her mom. He's not going to like hook up with her. He's going to support her and be there for her. He's there for his brother when his brother has his meltdown. He's there for his sister, with the baby and visiting Jack. He's there for his mom. He wants to reconnect with her and tries so hard. He's trying really hard with Miguel. You're totally right. I mean, this is crazy, right? He's the one like he's the one that's kind of stuck together. I can't even believe that.

Discover your new favorite show: Watch This Now!

There were a lot of moments in this episode where he could have reverted back to his old ways and didn't. It was cool that he called Sophie to ask if it was okay for him to come to the reception.
Hartley:
That was good. That was a well-written scene. I read that, and I was like, "Oh, he's standing on the lawn with a box of donuts. That's so cool." That was really romantic and cool. I don't think he was doing it [with romantic intentions]. I think he was doing it, like, just really trying to be there for her and to give her something that she gave him when his father passed away.

It was obviously emotional to be there for Sophie when her mom died, but Kevin still doesn't know about Rebecca. Can you tease what we can expect when he finds out that she's in such a fragile state?
Hartley:
It's not great. That's awful, sad, terrible news...It's been in recent years — I don't think it was when he's a teenager, when he's a kid — I think in recent years, he's learned how to be there with his mom, and appreciate her and enjoy her company and her time and her humor and her grace. I think that's what's going to kind of carry him through this...This is what this is — the last parent, this is everything. He doesn't have kids. He's at home, alone.

You're directing the next episode. What was it like stepping behind the camera for that episode?
Hartley:
I mean, it was a little intimidating at first. I'm not going lie to you, just because it's This Is Us and it's like getting the keys to the castle, right? This is the show and it's the whole baby, and they're like, "Here you go. You asked for it." It ended up being like one of the highlights of my life, honestly...To be able to sit at the monitors and, in the moment, watch what these actors are doing from a different perspective, it was really extraordinary. Mandy and Chrissy, I think, in this episode are doing things and I don't think they've ever been better. It's great material. The writing was incredible, but I think you're going to see them do things that you haven't really seen yet, and that relationship is going to blossom and bloom.

This Is Us' Sterling K. Brown Reveals How Jack Pearson Shaped Randall's View of Therapy

We are still waiting for answers about who Kevin's fiancée is. What is your advice for fans that are chomping at the bit for those answers?
Hartley:
You can be patient, because it might take a little bit to figure out who this is. But at the same time, there is so much story in between now and when we find out who this is. Right now, and all of that story in between those two points, inform the end. It is so well put together. It is like a master class in how to tell a story. They've done an amazing job. It's really incredible.

This Is Us will return Tuesday, Feb. 11 with "Hell of a Week Part 3" at 9/8c on NBC.