Did you ever think this film would be received the way it has been?
No. I personally thought it was great. I thought the script was a very artful piece of work. But my tastes are never quite the same as those of the critical mass, so that it’s doing so well is a surprise to me.

What in particular attracted you about the piece?
I liked the simplicity of the story, the complexity of the characters and the way that so much was not being said between them. It reminded me of Chekhov. Basically, they just had these tremendously complex lives, and I thought it would be interesting to see if we could pull that off.”

One of the things that I particularly liked was they way the film showed the messiness of these people’s lives. The film does not tie everything up neatly at the end, but instead allows the characters’ lives to continue to flow where they will.
Exactly, that was really nice. It doesn’t have a Hollywood ending and I think that’s the way life is. We don’t have major striding triumphs; we have tiny little changes that may take years to actually institute. Yes, Terry’s changed at the end of the movie, but we’re not going to see the fruits of that change for another five or ten years. If at all.

One of the things that is never spoken about in the movie is the death of the siblings’ parents.
Never. And they never say the title of the movie, they only point at it.

It is that loss, though, or the unspoken grief that is still hanging around in the air, that is holding them back?
It’s funny because the movie starts with Sammy [Laura Linney] at her parents’ grave site, and sort of ends with Terry [Ruffalo] at the grave site. I think in a strange way, when they come back together, they’re a little bit arrested in their development. Terry’s still caught in being angry at the world for letting such a senseless thing happen to them, while she has to be the caretaker and try to find maybe a religious reason to justify it. Each of them has what the other needs to move onto the next level of their lives: He needs to be able to care for something other than himself, and she needs not to be able to care so much that she puts everything in front of herself. They are both stuck in the same place. The other interesting thing is that the little boy [Rory Culkin] is the same age Terry was when his parents were killed, and Terry has to come and take care of this fatherless child.

Did your relationship with Rory make you think more about your impending fatherhood and the responsibilities that come with it?
It kind of keyed me into the joy of it. I had such a good time with him. But yeah, I guess so. I did have a pretty profound sort of response to that kid.

How did you go about bonding?
We’d go looking for salamanders, running around in the woods, fishing, swimming and boating. We did everything, basically, offstage – off screen, I mean – that we ended up doing onscreen. Basically what happened was, he and I were the only ones that were left around the lodge when everyone else went off to work, and he would be at my door at seven O’clock in the morning going, ‘Mark! Mark!’ and we’d go out and just kid around.

The relationships in You Can Count Me feel so believable and are so rounded that I wondered whether, given your and Kenneth Lonergan’s backgrounds in theatre, you prepared for it in the same way you would a play.
We didn’t have as much time as we would if we were doing a play – we had about seven days -- but we did kind of approach it like it was a play. Kenny and I had done several one-act plays together, and for a lot of them we only had seven days rehearsal. So to me it just felt like another one of those. It grows in you, I find, if you start working on something like that. Then when you go away from it, even if you’re not consciously thinking about it, it continues to grow inside you somehow. When we got to those scenes a month later after rehearsing them, they were pretty rich. I think if you try to understand where you’re headed in a film, then you start filling in all spaces as you go along, because you know where you have to get to. I think that that made the relationships really layered and textured.

Because you and Kenneth have worked together before, do you now have a kind of shorthand?
Oh yeah, it’s very short. You have to get through ego before you can really communicate with people, and we already burned all that up. What’s left is pretty pure. We can get to understandings pretty quickly now.

Were there any scenes in the film that particularly resonated with you?
One of my favourite things that happened in the movie was when Laura and I are out on the porch and this moth’s just kind of flying around and I put my hand out, it flies into my hand and then flies away. It’s just a simple little thing but to me it kind of summed up the way we worked on the film. There was openness so that anything ould happen. The scene's spoken as written so there’s really no improvisation, but there’s an enormous amount of spontaneity. A lot of actors would go, ‘Will someone kill this f***ing moth! It’s bugging me.’ But to me, when I watch it, I get tingles because it’s the Cliff Notes of the entire experience for me.