The actor talks about what it's like to be under the supervision of Steve Martin in Shopgirl

He's always been 'that guy' in films. And Jason Schwartzman plays him again in Steve Martin's Shopgirl. The drama is based on Steve's novela of the same name. Jason is Jeremy, a quiet guy who finds an obsession in Claire Danes, but realizes he can't be that same guy if he wants to win her heart.

To do that, Jeremy goes on tour with a band and discovers who he really is. Jason also plays drums in a band called Phantom Planet and when I talked to him up in Toronto, he talked about that and having Steve on set to talk about his scenes.

Check out what else he had to say:

Did you have any bands in mind when you started this project?

Jason Schwartzman: Yeah, Flaming Lips; I was thinking of them because the leader is a true front man and they teach and motivate you; that's what Jeremy needed so I thought there needed to have a rock and roll wisdom attached to the lead singer. I think we actually tried to get Flaming Lips.

How much did you bring to the script to make Jeremy more than a one dimensional character?

Jason Schwartzman: The book and the script was a great place to start; Steve Martin is such an exquisite writer, he says what he means. So there was a tremendous blueprint for Jeremy and I feel Anand made that blueprint; I think it's a combination of everything. One thing that Steve said when he wrote the book was he didn't want to lie or contrive anything or make things convenient and have the character arrive here without logic. So a lot of the dots are already connected to make Jeremy real; it's hard to be a one dimensional human being, it's easier to be a one dimensional character so it was all kind of taken care of, I don't know what I added.

What were some of the discussions you had with Steve?

Jason Schwartzman: It's funny, we never really had a scene together, so it's funny to me to say that I was in a Steve Martin movie. But I never knew him as an actor, I only knew him as a writer. But he does bring with him that elegance even with the things he says, he's so precise, I don't know how he does it. We just did this interview and I just watched him like ‘did he just memorize all this stuff;' he never says ‘uh,' he never says ‘what.' Being there as the writer, he would just come and he would watch and I would ask him questions like ‘What do you mean by that?' or ‘Do you think it's like this?' And it's so helpful to have the guy who wrote it, especially Steve Martin, be there and talk you through it the way he meant it; the great thing also about him is he's so open. He came in and said ‘Why don't you try it like this?' He was suggesting things to me, he was investigating things; it's amazing to work with an investigative writer.

Was there any adlibbing or was it more to the book?

Jason Schwartzman: Yes, there was some adlibbing, but anything that was unscripted is connected to a sister line that was there. It was never ‘action' and then an element of surprise; you just can't do that, especially with this delicate material. So anything not scripted we would talk about before and Steve would be there. We would figure things out, just slightly, and why not try to get it in a couple different ways; I like that style, just putting things out, changing them, rearranging them. So anything adlibbed definitely had a point. And the great thing was Steve and Anand set up this frame, but the canvas was blank, in terms of improvisation or adlibbing.

How do you see this guy as a person?

Jason Schwartzman: That's one of the great things about Jeremy; he didn't over think things. Out of many of the characters I've played, he's super ‘in the moment,' almost maybe too much; maybe like most zen of them all. Sometimes he's offensive, like when she says ‘You look great' and he says ‘Thanks' and never thinks to say ‘You look great, too.' He's just like that, but in the book it says he just knows what's in front of him. He just feels things and says what he feels and is very unfiltered as a person. You know how a kid says something, but he doesn't realize what he's saying like ‘Why are you so ugly?' I don't think he would say something like that, but there's such an innocence you can't be offended by it, or it's funny. I think she (Claire) thinks it's funny that a person can exist like that. Regrettably, I would say things and then realize ‘Oh man, that was probably not the right thing to say.' But, the thing I related to most about to Jeremy was a sincere desire to be alive and to meet people; he's a pretty open-minded person and I think that's a great thing. I think at the end of the movie, Jeremy really isn't a changed person by any means, but he's open to changing. And that's what Steve and I talked about – to make this guy a changed person.

Shopgirl opens in theaters October 21st; it's rated R.