Filmmaker Paul Weitz is probably best known for “American Pie” and “Little Fockers,” neither of which is exactly Merchant-Ivory material. So it might come as a surprise to learn that Weitz considers himself as much a writer as a director or producer. In fact, he calls his new “Being Flynn,” a tale of two would-be authors, his “most personal” film yet.

“I get in trouble” when directing movies from other people’s scripts, he says. “I need to get the stuff under my skin on a writing level before I’m able to direct it. I just feel like a fake, otherwise.”

Based on Nick Flynn’s memoir, “Another [expletive] Night in Suck City,” “Being Flynn” is about a young man (played by Paul Dano) who hasn’t seen his overbearing father in 20 years. Jonathan Flynn (Robert De Niro) is a New York taxi driver who proclaims himself a great novelist — although he’s never had a word published.

In the movie, which opens in District theaters Friday, the aimless Nick takes a job at a homeless shelter and broods about his dead mother (Julianne Moore). Then Jonathan loses his job and his apartment and becomes a regular at the shelter where his son works. Jonathan expects Nick to behave as a loyal son, even though the older man never played the role of father.

An amiable, gentle-spoken man with tousled gray hair, Weitz sees parallels in the story to his own life. But his father, John Weitz, was no Jonathan Flynn. A Jewish refugee from Hitler’s Germany, John Weitz made it to the United States via Shanghai and served in the OSS during World War II. He didn’t end up in a homeless shelter.

“My father was a fashion designer who was pretty successful, but he always dreamed of being a writer,” Weitz recalls. “He thought fashion design was a really silly way to make a living. He would write until late at night.”

Flynn’s memoir appealed to Weitz as “beautifully written and quite poetic, but to me it boiled down to the central question. ‘Am I fated to become my father? Or can one create oneself?’ ”

The father-son relationship recalls “About a Boy,” the 2002 film that Weitz directed with his brother, Chris. “That is the predecessor,” Paul Weitz readily agrees. “The idea of unconventional parenting is at the core of that movie. Anything I can do to have it feel not like two movies, but like one, I’m keen to do.” That’s why he asked singer-songwriter Damon Gough (a.k.a. Badly Drawn Boy), who scored “About a Boy,” to do the same for “Being Flynn.”

It was while making “About a Boy” that Weitz met De Niro, who was one of that film’s producers. Later, they worked together on “Little Fockers.” “I’m really grateful that people will do repeat business with me,” Weitz says. “And I like the idea of creating some kind of troupe.”

Jonathan is as dismissive of others as he is celebratory of himself, which makes for some uncomfortable moments during the movie. “He’s in some ways a horrible person,” Weitz says. “He’s a racist and a homophobe.”

“I think that De Niro is capable of showing some really unpleasant things and, at the same time, weirdly allowing you entree into them.”

“In terms of the films that I sometimes work on as a producer,” Weitz adds, “I really hate casual use of homophobic terms. It was challenging to be in a position that, to be true to the character, I had to have him say things I find utterly objectionable. But that was the character.”

Although Jonathan is not a successful author, he behaves like a loudmouthed 20th-century literary superstar. He’s a Mailer or a Hemingway, while his son is cooler and quieter.

The two characters represent “a broader generational shift,’ Weitz says. “That idea of the hard-drinking, extremely articulate — I supposed you would call him a man’s man — is retreating into the past. I think that this younger generation is more ironic and self-protective.

“But I think that, regardless of when an artist is living, he’s always dealing with the question of how much of what he’s doing is ego and how much of it is for the sake of the piece that he’s trying to make.”

Weitz identifies with the younger Flynn, who has become a close friend. And, interestingly, Weitz does think of Jonathan Flynn as an artist. “One of the first things you hear from De Niro’s narration in the movie is, “America’s produced only three classic writers: Mark Twain, J.D. Salinger and Jonathan Flynn. So he has this delusional perspective on his greatness.”

“But there is a fun-house-mirror aspect to the story, because while the real Jonathan never did have his ‘masterpiece’ published, he’s had this memoir written about him, and now he’s been played in a movie by Robert De Niro. His massive egotism has remained intact,” Weitz says.

“When I went with De Niro and Nick Flynn to visit him in the assisted-care facility where he lives, he looked at De Niro and said, ‘So do you think you can pull this off?’

“And Nick said, ‘Well, Dad, he’s a very famous actor, he did ‘The Godfather,’ et cetera. And his father said, ‘Yeah, I hear you’re quite good. But can you play me?’ ”

Being Flynn

(102 minutes) opens Friday at Landmark E Street Cinema.