Edward Norton is one of those actors who has dealt with some serious issues onscreen. Race-hate in American History X, free speech in The People Vs Larry Flynt and, oh, everything in Fight Club.

In person, his range is equally broad. In conversation he unites the unlikely, with topics straying from Guy Ritchie's "terrific" take on Sherlock Holmes to economist Pavan Sukhdev's "incredible" report The Economics Of Ecosystems And Biodiversity. Yeah, watch out Us Weekly.

It was his ability to flip that first brought Norton to Hollywood's attention, after he snared the sweet/psycho showcase role in Primal Fear with Richard Gere. Fifteen years later, he's at it again. In Stone he stars opposite Robert De Niro as a convict who undergoes a spiritual transformation. Then there's Leaves Of Grass in which he's a classics professor facing a life crisis, starring opposite, er, himself.

In 2008, I spent time with Norton on the set of Leaves Of Grass in Shreveport, Louisiana and the complexities of the film were clear even then. At one point he joked: "Tim Blake Nelson said to me, 'I've always wanted to make a movie about philosophically contrapuntal twins.' Which I think probably disproves the Robert Evans maxim that if you can say what a film is about in three lines it's a hit and if you can say what it's about in one line it's a blockbuster …"

So it came to pass that both Leaves Of Grass and Stone have bypassed cinemas in the UK, and are landing on DVD this month. It's a surprise given the actor's sizeable following, but perhaps indicative of resistance to the risk of marketing indie ideas. Though Norton excels as the contrasting twins – one a smart-mouth pot-dealer, the other a repressed academic – Leaves Of Grass is hard to box, probably best described as being Coens-esque. Norton, though, is phlegmatic about its release. He's stopping over in London briefly after a trip to Africa working as an ambassador for the United Nations' biodiversity programme – "It's the issue of the era" – and supporting his conservation trust in Kenya. Over an orange juice in a Knightsbridge hotel, he certainly seems relaxed about going straight to DVD.

'I was in the cinema and a rat ran across the aisle … I sat there thinking: I could be watching this at home!'

"I'm not particularly precious about the theatrical experience any more," he says. "I still love it, but my experience equates with a lot of other people's. I went to see The King's Speech, and there's been this plague of bed bugs in New York City, with people getting them off the movie-theatre seats, so I was thinking about that and then a rat ran across the aisle!" He laughs: "I sat there thinking, 'I could be watching this at home!'"

Norton cites the shifting landscape of cinema – with the growing influence of downloads and discount retailers – as an "interesting moment" for a film industry that has failed to learn the lessons of its musical cousin. "The movie executives have had a decade to watch this happening to the record industry and yet they haven't done anything …"

He's also looking to a longer game. He contrasts the commercial success of some films he's been in – The Score, The Italian Job or Red Dragon – against the slow-burn appeal of his weightier films such as American History X, Fight Club or Down In The Valley.

"I have this embedded faith in the process through which films of a certain type get discovered on longer timelines," he says. "I mean, did you see [Alejandro González] Iñárritu's film Biutiful?" He shakes his head and smiles: "Fuck! I just don't think it gets better than that. It's such an unshowy, gorgeous, human performance [from Javier Bardem]. And nobody is going to see that movie right now – nobody – but we'll talk about it and it will unspool. And I don't think, long-term, like, Eat Pray Love is going to be a more definitive measure of Javier's worth as an actor than Biutiful, you know what I mean?" He laughs: "But, you know, things can be taken out of context and you can sound really snobby. I just love movies.

"Like, there's a difference between being discerning and being discriminating, you know? Like, I discern between Biutiful, which I think is like a masterpiece, and Star Trek, which is one of the best pieces of entertainment I've seen in a long time. But I don't discriminate. I love them both. If [Star Trek director] JJ Abrams called me and said, 'Look, let's do this cool thing', I'd run [to him] because I think there are people who are equally genius at making great entertainment."

Norton's last stab at blockbuster entertainment was 2008's The Incredible Hulk, a mixed experience for both actor and audience, which ended ugly when Norton didn't sign on for follow-up comic-book ensemble The Avengers and Marvel Studios' president of production Kevin Feige publicly maligned the star's collaborative spirit.

'You can look at Marvel's movies versus, say, The Dark Knight movies and there are very different value systems clearly on display'

"I don't really want to open that up too much," admits Norton. "Let's put it this way: you can look at that company's movies versus, say, The Dark Knight movies and there are very different value systems clearly on display. I think those guys have made it really, really clear what they are aiming at. And that's fine. I don't have any quibble with it, unless you tell me that your value system is something different, to get me involved …" He pauses: "It was a negotiation, it was about terms. The attempt to spin it as something else was pretty cheap and juvenile. But I had a great time making the film. It's all good, all gravy; we had one crack at it and now other people will have."

Next up for Norton is a production role, a TV adaptation of Undaunted Courage, a book by Stephen E Ambrose (Band Of Brothers) about Lewis and Clark's journey of discovery across America. In May he'll star in the latest outing from Royal Tenenbaums director Wes Anderson, a nice change of pace, after the heavy lifting of his recent work. "I couldn't be more in the mood to just, like, play in Wes's sandbox, you know what I mean? I think he's one of the most original and distinctive directors around."

For now, though, what is the 41-year-old's punchy pitch for Stone, to snare an audience? "It's a thriller but it's like a thriller done by Bergman," he laughs. "This is probably not going to make it fly off the video shelves! But I'm such a fan of [director] John Curran's. He's really, really going at deep themes, existential questions and challenging the whole idea of what constitutes an authentic spiritual experience."

He stops, again. "Er, I'll say something a little bit punchier! I think it's as good as De Niro has been in many, many years. I was amazed watching him while he was doing it and while I watched the film I was just gobsmacked by it, because it's so subversive and corrosive. So, for any De Niro fan, it's a really good one!"

Norton smiles; he's tried. People will find the film, which lingers long in the mind, in their own time. He's putting ideas out there, chewing over them, trying to make movies that give people "the sudden sensation that someone else feels the thing you're feeling … It's that CS Lewis thing. He said, 'We read to know we're not alone.'

"And that's the core of it," he concludes, "the sudden sensation that someone else feels the thing you're feeling."

Leaves Of Grass is out on DVD now. Stone is out on 28 Mar