I never quite understood how Brian could do it, but after all of these years, I've gotten pretty adept at it myself.
Not listening to him when he talks.
Early on, I'd tell him things, thinking he was listening, only to find out days later when I brought the subject back up, that he hadn't "heard" a word I'd said. Since I'm an only child, I never learned the skill of blocking out when people talked to me. I always gave them my full attention. Brian was raised in a full family. Two brothers, two sisters, a foster sister, always a full house. So, it's natural that he'd have acquired the skill of verbal blocking.
Since he's been working from home and spending a lot more time next to me in the office and my frustration level has been rising because every time he mumbles something, be it a rant about how someone is a moron to how messed up his computer is (which often turned out to be operator error - the problem wasn't replicated when I was watching what he'd done), my mind changes what it's concentrating on to give him its full attention. This morning as I was typing I realized he was talking and I hadn't been listening to a word he said.
Wow. I think I'll like this.