[Warning: This story contains spoilers from the "Tell Me You F—ing Need Me" episode of Showtime's Shameless.]

The last time Jimmy/Steve (Justin Chatwin) left Showtime’s South Side family dramedy Shameless, it seemed pretty permanent. He was seemingly killed by a drug lord after getting mixed up with his daughter in a green card marriage. But the smooth-talking character lived to see another day and return to Fiona's (Emmy Rossum) life — only to leave again after a three-episode arc.

“This time it felt different. The writing felt different. It does feel like Fiona knows that he isn’t the be all and end all for her," Rossum told The Hollywood Reporter. "And that doesn’t mean that Gus (Steve Kazee) is or that Sean (Dermot Mulroney) is, but that she’s defined it in her life where she doesn’t want to be that person anymore. She’s closing that door to that chapter and opening the door to the first chapter of her becoming who she’s going to be."

Read more 'Shameless' Postmortem: Emmy Rossum on Fiona's "Desperate Attempt" at Stability

“What’s really interesting about this time around is I think Fiona has been through so much — real life trauma — without Jimmy and actually gotten stronger, and I don’t think she [was] as penetrable to his charms and manipulations as she once was. Their relationship evolved into something different than it was before. It had to because he hasn’t changed and she has.”

THR caught up with Chatwin for his take on Jimmy/Steve's surprise return and subsequent exit — again.

It was a big surprise to Shameless viewers — and the cast — when Jimmy/Steve showed up at the end of season four. At what point did you know you were returning — that he hadn't died on that boat after all?

I was shocked; I thought he was dead; I had made a head cast, which is when they're probably going to blow off your head or chop off your head, so I was 100 percent certain that my character was deceased. Andrew Stearn, [showrunner] John Wells' right-hand man, called and said John had an idea. I guess there had been a lot of rallying from Emmy and the cast to bring back my character because [they] felt like something was missing — maybe some heart — that they felt our relationship brought out in the story. And I think there had been a rally from some fans who liked that character [too] and so John asked me, "How do you feel about this?" When he [explained the end of season four] to me, I got chills that just ran down my spine.

Read more 'Shameless' Boss on the Surprising Finale: Fans Demanded More

You’ve been away from the show for some time. What was the biggest adjustment for you stepping back into the role and the world?

I was nervous, but when you get back on that stage and the writers know your character so well [it comes back immediately]. For me, that whole show, for my character, is standing in front of Emmy terrified of what she's going to say and how she's going to yell at me. (Laughs.) And it's exciting, and it's scary — like stepping into a cage with a lion — but that's the world that Jimmy/Steve can only play in. It's life or death, love or death. So, I actually felt like after I had had so much space from the character, I think I [got] a bigger understanding [of him]. The longer you're on a show, you start really understanding what the show's about and the device your character plays, so just coming back on this show with such drive and love to try to get [Fiona] back was such fun.

He gave Fiona quite a few lines — about being tied up for a chunk of the time he was away, about having a job overseas he wanted her to come with him to — how much of what he said to her was real?

I think that's up to the audience to interpret. From my perspective when I was saying those things, if I play Jimmy/Steve from the perspective of "I don't really mean these things" then I'm playing a sociopath, and you can't play a character like that. A character has to believe everything that he's saying, so of course, absolutely, 100 percent that character has to believe everything that he's saying. And I think from the beginning of the show he's always believed everything that he's said to her.

Read more William H. Macy: Directing 'Shameless' Was the "Hardest Thing I've Ever Done"

Even after everything they've been through now — how Fiona reacted after thinking Jimmy/Steve abandoned her, how out of sync he was with her when stepping into her life now — were you rooting for them?

It's interesting because when I was pitched the show, [they] said that this [relationship] is a really f—ed up version of true love. These two are meant for each other; they are the heart of the story; it's Romeo & Juliet. So, I've always rooted for the two of them because they were both really damaged people [whose] hearts lined up because they were both broken.

At the end of “Tell Me You F—ing Need Me,” Fiona ultimately rejects him. Do you really think that's forever, or is there room for him to pop in and out of her life as seasons go on?

I'm really looking forward to seeing how the fans react to it and if that's what they want or if it does feel final. I remember in the read-through for that last episode, [exec producer] Nancy Pimental's episode, it says, "Jimmy drives off. And that is the end. That we ever see of him for ever and ever." And the entire cast and execs all started bursting out laughing because they'd written that at the end of my exit every time now, and it never seems to work. When I first got on the show, John Wells said the show is like a plant in a garden, and it grows; you never know in what direction it's going to go, or what it's going to produce, or what it's going to look like. So people will leave and people will return and people will change.

Shameless airs Sundays at 9 p.m. on Showtime. What did you think of Chatwin's return? Sound off in the comments below.

Twitter: @danielletbd