But that doesn't mean her participation was an easy sell. "I pitched it to her really well," Webber, 31, said the day after the Jan. 21 premiere.
"I said, 'Listen, I've got a great idea to make a film, to really honor our son and this moment in time, and to do something that hasn't been done before.' Her being an artist, she was able to appreciate that, and I think take one for the team. She was maybe a little resistant at first, but she came around."
The son of homeless-rights advocate Cheri Honkala, the Green Party's candidate for Philadelphia sheriff in the November elections, Webber spent part of his childhood living on the street, an experience that fed into his politicized first feature, Explicit Ills (2008). That movie offered four interconnecting stories of love, drugs, and poverty in Philadelphia.
The End of Love focuses on Webber more as actor than activist. Unlike Webber, who has acted in dozens of films - including three shown before Sundance ended Sunday - his character is still struggling. In the new film, he blows an audition with Amanda Seyfried and sneaks onto a set to borrow money from pal Jason Ritter. At a party thrown by Michael Cera (who starred with Webber in Scott Pilgrim vs. the World), Mark is surrounded by young stars such as Aubrey Plaza and Alia Shawkat, doubly alienated by his lack of success and the fact that he has a babysitter waiting at home.
With Shaw, the stumbling block wasn't her fictional death so much as the mechanics of shooting with a 2-year-old child. The goal during filming with their son was to be as unobtrusive as possible, using Canon 5Ds that look like ordinary still cameras.
"Our child's well-being is the most important thing, which is why he's not here and I'm not pimping him out taking red-carpet photos with him, because he would hate that and it would be traumatic," Webber said. "I spent months with my director of photography figuring out if this is even possible. How can we make a movie without making a movie? Can we do it without slating, can we do it without lights, can we do it without a crew? That was all to make sure that there was nothing that was going to affect him adversely."
Although Webber is playing a character, the scenes with his son feel entirely unforced, whether he's feeding Isaac his morning cereal or explaining the nature of life and death. Their interactions capture a stage of parent-child relations rarely seen on screen; it's hard enough to get a toddler to finish a meal, let alone take direction. Isaac didn't need coaching to act like his father's son, but embodying a shell-shocked widower proved more difficult than Webber predicted. There was no way for Webber to explain to a 2-year-old that he was simply acting depressed and withdrawing, so he had to adjust his performance on the fly, getting the requisite material without leading his son too far afield.
"That was the hardest part of making the movie," Webber said. "I spent so much time figuring out the technical side of it, so that he wouldn't be weirded out by a camera in his face, that I underestimated a bit my way of being around him. It was understated and subtle, but you feel it. That's why we would shoot in very short bursts, and afterwards I would do some major overcompensation and go right back to normal. That was on me as a parent to gauge and stagger properly, because it made me very uncomfortable."
Webber had far greater latitude in the scenes he shot without Isaac, when his character truly goes off the rails. When he's not keeping it together for his son's sake, Webber's character is a walking raw nerve. He's so desperate to fill the void left by his wife's passing that he proposes marriage to two women after a few drinks.
At Cera's house in the film, things get particularly out of hand. Webber's character gets drunk and high, and Cera starts wielding a handgun, offering guests $2,000 to put it to their heads and pull the trigger. The tongue-in-cheek parody of Cera's nerdy image took Webber off guard.
"I had no idea," he says, laughing. "Michael brought a gun and that was all him."
But it's of a piece with the movie's darker themes, where moments of happiness abruptly give way to genuine threats, including a harrowing finale in which Webber and son find themselves out on the street. "I needed just a little bit of danger to ramp things up in the final act," Webber said. "I think that was more interesting as a filmmaker than saying, 'They're going to be OK!' or the opposite, which is they're screwed. I definitely did not want to do that at all."