Not long after the 2008 Democratic Convention, Barack Obama had a chilly phone conversation with his running mate, Joe Biden. Obama was annoyed that Biden seemed to be saying something stupid on the campaign trail practically every week. This time it was Biden aimlessly speculating that Obama would be “tested” overseas after becoming president, which highlighted the nominee’s inexperience.

That testing didn’t happen, but something else did: Obama and Biden became exceptionally close, arguably the closest of any president and vice president in American history. How that happened tells us something important this campaign season.

With Biden, familiarity breeds not contempt, but respect and even love. As his admiring old Senate colleagues and loyal staff attest, the longer you know him, the better he looks.