Brendan and Smith welcomed their first son, Griffin Arthur Fraser, on 17 Sept., 2002. Since Griffin isn't in the spotlight and doesn't appear to have any social media accounts, there's not much that we know about him other than what Brendan has said about him in interviews.
For example, while speaking to GQ in February 2018, Brendan revealed for the first time that Griffin is on the autism spectrum. "He needs extra love in the world, and he gets it," Brendan said, adding that Griffin's younger brothers have always felt the need to protect him. "Ever since they were small, one was always the spokesperson and the other was the enforcer."
Brendan also told GQ that Griffin is "a curative on everyone who meets him," explaining he helps bring out the best in people. "People have some rough edges to them. Or he just makes them, I don't know…put things into sharper relief and maybe find a way to have a little bit more compassion," he said. "They don't put themselves first so much around him."
The actor continued opening up about Griffin by revealing he's built a strong connection with their horse, Pecas. "There's something good that happens between the two of them. And even if he doesn't ride him, just give him a brush. The horse loves it, the repetitive motion that kids on the spectrum have that they love. And it just works," he said. "You know, you have to find those tools, strategies. If I ride, too, I just feel better. I just feel better."
In a November 2022 conversation with Freddie Prinze Jr. for Interview, Brendan said that his relationship with Griffin helped him connect with his role as Charlie in "The Whale." "My oldest son Griffin has special needs. He's autistic. He just turned 20. He's a big kid. He's six foot five. He's got big hands and feet, a big body. I understand intimately what it is to be close to a person who lives with obesity," Brendan said, adding that Griffin is the "happiest person." "And because of the beauty of his spectrum — call it a disorder if you will, I disagree with you — he knows nothing of irony. He doesn't know what cynicism is. You can't insult him. He can't insult you," he said.