Get the tissues ready: NBC's family drama phenom "This Is Us" returns for a second season tonight, and based on what the cast has revealed to Moviefone the storylines are poised to once again hit the audience right in the feels.

Sterling K. Brown, the newly minted Outstanding Lead Actor in a Drama Series Emmy winner for his performance as Randall Pearson in the show's freshman season, admits he was eager to slip back into Randall's very sensitive skin. "He has such incredible highs because his heart is so wide open," says Brown. "It also means that he can have it broken. It's been a joy to play him. I hope to be able to do it for several years to come because you don't see people wear their hearts on their sleeve the way this character does."

The season will kick off following Randall's intention to adopt a child, "He's very conscious of wanting to pay homage to his mother and father and to William's legacy, and try to do something for a young person that was done for him," says Brown. "The thing is, he has a different wife and she has different ideas on how that's supposed to self-actualize, so I can't do it exactly the way Jack and Rebecca do it because Randall and Beth are their own couple. So I have to pay respect to that couple hood and see how we decide to move forward as a unit."

Indeed, there may be some points of contention regarding the adoption issue, hints Susan Kelechi Watson, who plays Beth. "We're going to open with Beth sort of presenting her side on this adoption issue that's been coming up, and what it means to her," says Watson. "What part of her life she feels will be affected by it and all those types of things. We'll have a chance to see her and Randall on two different pages, for once."

Viewers can expect to learn a little bit more about Beth's backstory as well. "Last season was really about meeting the Pearsons, the core family, and that's an important story to set up," explains Watson. "And now we get to branch off into some other things, and explore other relationships, so we will get a chance to see myself and the Pearsons, a little bit of my family."

Justin Hartley's character Kevin Pearson's professional circle will broaden to include his new co-star Sylvester Stallone – the iconic action hero will guest star as himself. "He's in the movie with Kevin so he's playing a character, and he's Sylvester Stallone playing a character, so he's playing himself as well – he's great at it!" says Hartley.

"He's such a good actor that it just comes across so natural and everything, what he does," says Hartley, who had as much fun with Stallone off-screen as he did on. "He just comes to work, makes everyone laugh, puts everyone at ease, and then gives a wonderful performance. Tells great stories, then he leaves – I'm like, 'That's cool walking through the door right there.'"

Chris Sullivan, who plays Toby Damon, agrees, having met Stallone while both actors worked on "Guardians of the Galaxy Vol. 2," in which Sullivan was buried under prosthetics as Tazerface. "When Sylvester Stallone walks on the set, everyone is a 12-year-old kid. Everyone is like, 'That's Rocky!" Everyone wants to meet him," says Sullivan. "He walked up to me, and was like, 'Hey, you mind if I get a photo?' I'm just like, 'Sylvester Stallone wants a photo with me!' I had completely forgotten that I'm covered in this amazing special effects makeup – he wants a photo with the makeup. He didn't want a photo with me."

"But he came on the set here, and he remembered me!" adds Sullivan. "That was blowing my mind, that Sylvester Stallone remembered me. Now I have a photo without the makeup."

Sullivan says Toby will be doing his best to keep his romance with Kate Pearson thriving. "We're going to see him and Kate really doubling down on their relationship, kind of getting past all the courting, all of the grand gestures and really getting down to like building a foundation for a long-lasting relationship," he reveals. Does Toby have a truly sincere and intimate relationship in him? "I hope so. I want to be on this show for like six more seasons!"

The actress behind Kate, Chrissy Metz, is in agreement. "I don't want Chris going anywhere. Never," she says. That means, however, that the couple has some work ahead of them if they hope to stabilize their connection.

"Here's the thing," says Metz. "I think we all have pockets of bliss and being in love with our partners in some capacity. But what's so beautiful about the writing is that there are swings, and ups and downs. Unconditional love is all through that, all through the really difficult parts, and then the really beautiful moments. So I think that's real love, and real love is intimacy. The intimacy is honesty, and I think what's really beautiful and people relate to, is that they're really brutally honest with each other."

Kate's also branching out creatively and professionally. "She's really making it a point to pursue her singing career, sort of following her mother's footsteps – and what does that mean for her?" says Metz. "She's a mid-30s girl who's never sang, and she's in Los Angeles. It's not like she's in New York and doing theater, where it's a little more acceptable – it's a little different game. So there's ups and downs, and there's swings and shifts, so we're going to get to see all of that, and how it plays out – and how it of course affects Toby and Kate's relationship."

The storyline has been a thrill to Metz, who reveals that she was never encouraged to pursue her own musical ambitions, despite her stunning pipes. "It was always like, 'Oh, you're going to be a comedian. You're funny. I don't know if music is your thing,'" she says. "It was always something I wanted to do, but it was never really encouraged. So in that capacity, I totally get it, sort of feeling like friends or people who have found success or are better than I am."

"Then I realized, everybody's voice is different. Everybody's acting is different," she adds. "We can all appreciate any of those things. It's a little tricky because she's still in that beginning stages of her music. She's never been, like, properly trained or any of that. So it's like this real raw vulnerability that I love. I think that's what people relate to in music."

As Kate's mother Rebecca, Mandy Moore says she was eager to crack open the source of the two characters' unspoken friction, "why it's so sort of frayed and disconnected in the present day. It's interesting to sort of see the parallels in their lives with music, and where sort of, maybe, the resentment started with her mother. It's like two sides of the same coin. They're both right and they're both wrong."

"I read it, and I bawled," Moore admits. "I was like, 'I think I have some stuff I need to deal with with my own mother.' It really touched something in me."

And then there's the lingering mystery in the show's flashback sequences regarding the doomed fate of Milo Ventimiglia's Jack Pearson, the super-dad of the Big Three who's grappling with the imperfections in his relationship with Rebecca that resulted in that fiery, wounding argument that closed out Season One.

"We find them in that immediate fractured moment just beyond," says Ventimiglia, "and they have a long, uneven, unpaved road to walk to get back to being better. Some hurtful things were said, some things that you never want to bring into a relationship but the intensity of that fight is always going to cool off. But what doesn't go away is the hurt and the pain and what these people who have spent twenty years together experience."

"For all Jack's perfection, or perceived perfection, I think what we're going to see a lot of this year is Jack's imperfection," adds Ventimiglia. "Not that we're going to see Jack acting poorly or being poorly. We're just going to address the things that have impacted his life to where he puts on this 'amazing man' quality, but really buries everything else because he does not want it anywhere near his family, anywhere near his wife, anywhere near his kids."