By Jenny Halper in New York City

On the set of “Lucky Number Slevin,” Josh Hartnett wandered around shirtless, sticking out his stomach and asking director Paul McGuigan if he could play the title character with a bit of a gut.

“He said ‘No!'” the actor laughs. “I felt like the character should be soft and vulnerable and almost non-threatening in any way. I didn't work out at all. I wanted to gain weight for it.”

Whether Hartnett likes it or not, his Slevin, an unsuspecting pawn in a deadly battle between the Boss (Morgan Freeman) and the Rabbi (Ben Kingsley), can't help coming off as a heroic heartthrob. That's good news for his pretty neighbor Lindsey (Lucy Liu), a coroner who shows up requesting sugar – literally and figuratively.

Q: I'll start with the most original question ever- why did you choose this film?

JOSH: I thought that it was a multi-faceted character. You got to do a lot of different things and go through a lot of different emotions. My buddy Jason (Smilovic) wrote the script and so it was nice that he was a friend, and I had friends who helped produce it. When Paul (McGuigan) said that he wanted to direct it I couldn't say no.

Q: And you'd worked with Paul before?

JOSH: Paul and I have had a tumultuous and exciting relationship because we started together, we did this film “ Wicker Park .” We were at odds with some people while we were filming it and it was difficult and everyone was fighting for elbow room to sort of create what we thought we should be creating and it became a really strained film set. We knew though that we wanted to work together again under kind of a looser environment where we would be allowed to experiment and do what we feel. This is what we came up with. It was great to get help from guys like Morgan Freeman and Ben Kingsley and Bruce Willis.

Q: Your scenes with Lucy had a really loose tone- were they improvised at all?

JOSH: Lucy and I got to improvise a lot more than anyone else. I like that Paul didn't try to make the entire film seem cohesive because it all had a similar tonal quality. There's the really dark moments and the really comic moments that are cut like a comedy. So he lets things sort of go all over the place because the story ultimately is all over the place and he recognizes that. So in a lesser director's hands it would've been a totally different film.

Q: How do you feel about revenge?

JOSH: If you're asking if this film is condoning revenge as a way of life…I'm not condoning it. I don't think that that's the story I found interesting. It was more because of the multi-layers within the characters and the dialogue. I don't particularly think the idea of revenge is a good one. I've never sought out revenge in my own life. I don't think that it's a particularly satisfying way to get over feeling lost and I think that's what I came to when I was filming this.

Q: What do you think the message of the film is?

JOSH: This film (is) more about kind of luck and chance. The idea that you're never quite sure of who you're dealing with. Forces are at work beyond your control. But this film wasn't really a thematic film, not a clear thematic film like a “Match Point” or something like that where there is a definite theme that you can point at and say, “That's what this film is about.”

Q: We haven't seen you in a blockbuster in a while.

JOSH: No, because I kind of turned away the big thing. I went and did my share of films that were in that line of like “You're going to be whatever.” They try and push you into the hero mold and I just felt like I wanted to play more interesting characters. I wanted my film career to more about who I am as a kind of eclectic human being, someone who likes different things and likes to play different kinds of characters. I mean, we have a lot of stuff in us as people and I want to explore that. I think that Orson Wells said that the creation of character is just about stripping away layers of yourself because it's all in you. I didn't get into this to make the most amount of money and to command the most respect on set, or have the most clout and scare people. That's not what I'm doing here.

Q: What do you want to do in the future?

JOSH: I think that I would like to be able to do it my way, but I would like to be able to continue to make films and in order to do that you need to have success, whether they be acting successes or monetary successes. I want it to be about the acting. I did this film and then I did a film called “Black Dahlia” and now I'm going to do this movie called “Resurrecting the Champ.” I hope that I'm going to prove and continue to prove throughout my life that I really care about my craft and hopefully people will enjoy the characters that I play, and not necessarily just the look or whatever.

Q: How do you get yourself into the mind of a character that you're playing?

JOSH: Usually from a psychological place first. I try to find out where the character has been and where he's going. And then I try to find the few things that are going to get me into the character like how he walks maybe or how he talks. You find that a great character is written. You can't necessarily make a great character out of a poorly written script and so if it's not there on the page I realize you can't do that. I used to try all the time – I was like, “if it only had this or that.” So now I'm just trying to make sure that there's a lot of meat on the bone when I find a character.

Q: Do you keep a journal?

JOSH: Not normally. I mean, there are a million different – I write from the character's perspective occasionally, when I really feel like I needed it, but I guess that I never thought of it as a journal. I mean, there are those words and ideas that you use in theater school…I only went to for nine months. All the stuff that I learned is probably in the back of my mind somewhere. So I make my own way of doing it and I learn all of these things from all these different actors on set, watching Ben Kingsley, watching Morgan Freeman, watching Harrison Ford, Hilary Swank. Now I'm going to work with Sam Jackson. You watch all these guys doing their work and you learn all these disparate lessons and sometimes they don't work together, so you just have to kind of find your own way of working.

“Lucky Number Slevin” opens on April 7th.