Incredibles 2 reflects director Brad Bird's deeply personal lessons in daddyhood

Brad Bird laughs readily when talking about how parenting can be like Kryptonite, rendering even the most mighty of people utterly tested, torn and fatigued.

"It takes it out of you," says Bird, the writer-director of The Incredibles 2, as well as the father of three boys.

So of course, a key theme in the new Pixar sequel is how Bob Parr (voiced by Craig T. Nelson), when not suiting up as Mr Incredible, is a dad left unshaven and spent by the domestic trials of raising three kids of his own — while wife Helen (Holly Hunter) fights solo as Elastigirl.

This depiction is from a knowing place, as Bird calls the Incredibles franchise "strangely personal". And when talking about the sequel, Bird reflects on how much he has experienced as a parent, especially over the past 14 years, since the first Incredibles film was released.

"I had a real bachelor's notion of what having children would be like," Bird tells The Washington Post.

The director thought: "I'm going to start them out on silent films and so they'll think they're cool, and they won't know that they're really old. And then I'm going to do this. And then I'm going to do that. And it'll be fun. They're little blobs that have no individuality until they have start to have life experience.

"Basically," Bird says, "everything I was thinking was wrong."

From the very beginning of their lives, Bird learned, "they're different and individuals".

Pixar filmmakers have long tapped specific personal experiences as parents. Andrew Stanton, for instance, told The Post that while making Finding Nemo, with two small boys and a sprightly father of his own, he was very aware of being "both the son and the father at the same time". And Pete Doctor told The Post how a shift in his daughter's mood one morning, at age 11, helped spark the story engine that led to Inside Out.

Bird, for his part, recalls one moment with his eldest son, Michael, then a primary grade-schooler.

"There was a time when he just wasn't minding (my instruction) at all, and I almost wanted to spank him," says Bird, emphasising that he does not spank his children. "And then I looked at him and I realised that he was acting up because I hadn't been around in a while. And I just hesitated and I looked at him and I said: 'I know I haven't been around a lot.'"

Bird apologised. His son melted. They hugged. It was, the director says, "a great bonding moment".

"I put him to bed. And everything was fine. And I thought: OK, that's taken care of," he says.

"But it's not.

"The next morning is a brand new day and ... you're never done with parenting, really."

Such is life as a father, when you're Bob Parr - or Brad Bird.