“James Franco plays gay!” is not an announcement that would qualify as a marmalade-dropper. The actor has taken on enough gay parts (including Allen Ginsberg in Howl and the activist Scott Smith in Milk) and addressed gay themes so frequently in his own directing work (such as Sal and Interior. Leather Bar.) that he has arguably passed through the rumour barrier and emerged out the other side. Where more circumspect performers invite speculation through their very cautiousness, there can be few people who even care any more about whether or not Franco is gay.

Sundance 2015 review: I Am Michael – James Franco's gay pastor shallow Read more

But I Am Michael, one of the six or seven new films in which this prolific actor will be seen this year, is no straightforward gay movie. Franco plays Michael Glatze, a real-life former activist and editor of various US youth magazines. Despite being in a long-term relationship (his partner is played by Zachary Quinto), he underwent a mysterious religious conversion. Soon Glatze had denounced his former life to become an anti-gay Christian pastor. It was Gus Van Sant who alerted Franco to a New York Times article about Glatze; the veteran film-maker also recommended the first-time writer-director Justin Kelly to adapt it. (Kelly, who has directed music videos and shorts, was assistant editor on Van Sant’s Milk.) “I didn’t quite know how it would work as a movie,” says the 36-year-old Franco, “but I trusted Gus’s tastes.”

Sitting alongside me in a conference room overlooking Berlin, actor and director have a loose, giggly rapport. Franco, swaddled in a baggy black cable-knit cardigan over a red lumberjack shirt, toys with his beard as he talks. Kelly, an elfin 34-year-old, sits bolt upright in a yellow-and-black bomber jacket. “When I met with Michael, he explained it was all really simple,” the director recalls. “He firmly believes that the Bible is the word of God: ‘You have to be straight to go to Heaven and I want to go to Heaven.’ To hear him say that was so helpful. Until that point I’d read all his anti-gay rants so it was quite hard to care about him. But when we met, I saw he was a really smart guy, very human. I don’t want him to judge me, so I shouldn’t judge him.”

Franco, sprawled in his chair, springs suddenly into life. “I wonder if some of those rants were kind of secondary to the whole thing,” he announces. “He had been so public as a gay activist, and maybe there was this misguided need to burn down everything he was before. The activism was so public that the rejection of it had to be public too. He was trying to be a role model, as he had been before, but he couldn’t acknowledge that his messages had become hateful.”

Facebook Twitter Pinterest On screen bromance: Franco with Seth Rogen in Pineapple Express. Photograph: Snap Stills/REX

Perhaps homosexuality wasn’t even part of Glatze’s problem. Along with, say, coffee or hair dye, it was simply another part of his old life that he rejected after embracing religion. Franco gives the matter some careful thought. After the longest “ummm”, he lets out a decisive, celebratory “Yeah!” and his face melts into a grin. “It’s like what Zachary said when we were making the film: this isn’t a character who sought to change his sexuality because he was uncomfortable with it, or even sought to change it at all. It came about because he was pursuing something else. He got caught up in religion and took on beliefs that made him turn against his own sexuality. It wasn’t like he was ever tortured over it until these other beliefs came into play.” For Kelly, that was a deal-breaker: “Had Michael been unhappy in his gay life, I probably wouldn’t have wanted to do the movie.”

What is missed in emphasising Franco’s own interest in gay subject matter is that it is the fluidity of identity, rather than sexuality alone, that stimulates him. To that end, his career and persona have the aura of an ongoing installation. The living, breathing James Franco multimedia museum incorporates everything from his Twitter posts and fiction to his art exhibitions and his on-screen bromance with Seth Rogen (in Pineapple Express, This is the End – in which Franco played an exaggerated version of himself, swooning openly over his incredulous co-star – and the North Korea-baiting The Interview).

Facebook Twitter Pinterest Franco in Wim Wenders’ 3D drama Every Thing Will Be Fine.

That impression was intensified at the Berlin film festival this week, where Franco starred in two other movies alongside I Am Michael: Werner Herzog’s Queen of the Desert and Wim Wenders’s 3D drama Every Thing Will Be Fine. His performance as a tormented novelist in the latter was quietly accomplished, prompting laughter from the audience only when the character was asked questions to which we could guess Franco’s own response. “Do you like Faulkner?” for instance. (Well, duh. He’s written, directed and starred in two adaptations of the novelist’s work.) Or: “Is there nothing that can get to you?” (The unflappable actor once complained to me that everyone always imagines he’s high: “I guess people think I’m stoned the whole time because of the way I talk.”)

It’s instructive to see I Am Michael in close proximity to The Interview, since they show two sides of the same Franco. Glatze and Dave Skylark, the blithely narcissistic talkshow host asked by the CIA to assassinate Kim Jong-un, are prone to delusional behaviour that insulates them inside unreachable worlds. Glatze can’t see what’s wrong with a formerly gay man proclaiming “Turn or burn!” any more than Skylark is aware of his own intellectual impoverishment. (Hearing Kim Jong-un mention Stalin, Skylark corrects him sympathetically: “In my country, it’s pronounced ‘Stallone.’”) One is played for laughs, the other for numbed tragedy.

More than ever it seems spurious to separate the funny Franco from the brow-furrowing one. Aren’t they all part of the same continuum? He lobs another emphatic “Yeah!” into the silence. “I see everything as connected in one way or another. One of the things I pride myself on is being able to fit into whatever film I do. Now, hopefully, I don’t choose a film that I can’t fit into, but once I do sign on, I’m not trying to make that film conform to me – I want to conform to the tone and flavour of the film. I want the character to fit that film. So in one sense, I’m doing the same thing and using some similar tools as an actor. But in The Interview, I’m emphasising improvisational skills and seeing how far I can go because the character wants to go that far. I’m pushing the limits. Whereas in I Am Michael, it’s clearly more subtle. But in other ways they’re totally the same. It’s just about finding the dimensions of the character.”

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The extremes of Glatze’s dogma did not always transfer smoothly to the screen. “There were a few things we ended up changing because I said, ‘Um, this is a little crazy, what he’s saying here.’ Not even the homophobic stuff, just … nuts! Justin would tell me, ‘He really said it!’” He gives a cackle and Kelly explains: “In the scene where his friend says he wants to be an astronaut, Michael told him, ‘Well, don’t go too far into space because you’ll bump into Him.’ I remember James saying, ‘This is not working!’ and I was, like, ‘It’s gonna work.’ And it totally didn’t.”

Both movies provide a helpful reminder that Franco is a thoughtful and nuanced actor beneath all the media brouhaha – whether it’s the cyber-hacking campaign believed to have been directed at Sony by North Korea in retaliation for The Interview, or his intimate Instagram chat with a 17-year-old girl (which may or may not have been a viral marketing stunt for the film of his story collection Palo Alto). Nowhere is this more apparent than in the crisis points of I Am Michael, all of which rest on tight close-ups of the star: in the shower following a health scare, staring at a gay couple in the supermarket or waiting in church to greet his first congregation.

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“I was taken aback by James’s ability to become Michael at any given moment,” Kelly tells me. “Within one day we might shoot gay Michael with blond hair, then gay Michael with brown hair, then straight Michael. It was all over the place but his performance is so subtle, the arc so gradual. I’d watch the monitor and I’d go, ‘This is crazy.’”

It would be remiss before our time is up not to ask whether anything positive came out of the furore over The Interview. But the publicist, who has slipped into the room, has other ideas, clearing his throat to overrule me. “No, it’s fine,” Franco insists with a smile. “I’ll answer this. First and foremost I think The Interview is a great film. I’m so proud of the work that we did. That can get lost when something like this happens. I feel people can’t see the film clearly any more. But we knew we were taking on a little bit more than just a stoner comedy with that subject matter, so maybe by doing that it became more than just a funny, well-made movie. More than that, I’m really sad that [former Sony head] Amy Pascal is a scapegoat. That a strong woman in cinema has to take the blame is, I think, a real shame. I did many projects with her, and she was nothing but a great person and a great executive.”

• I Am Michael is the opening film in the Flare: London LGBT festival on 19 March and will open later this year. The Interview is on release

