But behind all the BFF bonhomie is a much more complicated story—one fueled by the misgivings the 44th president had about the would-be 46th, the deep hurt still felt among Biden’s allies over how Obama embraced Hillary Clinton as his successor, and a powerful sense of pride that is driving Biden to prove that the former president and many of his aides underestimated the very real strengths of his partner.

“He was loyal, I think, to Obama in every way in terms of defending and standing by him, even probably when he disagreed with what Obama was doing,” recalled Leon Panetta, Obama’s secretary of Defense. “To some extent, [he] oftentimes felt that that loyalty was not being rewarded.”…

Interviews with dozens of senior officials of the Obama-Biden administration painted a picture of eight years during which the president and vice president enjoyed a genuinely close personal relationship, built particularly around devotion to family, while at the same time many senior aides, sometimes tacitly encouraged by the president’s behavior, dismissed Biden as eccentric and a practitioner of an old, outmoded style of politics.

“You could certainly see technocratic eye-rolling at times,” said Jen Psaki, the former White House communications director. Young White House aides frequently mocked Biden’s gaffes and lack of discipline in comparison to the almost clerical Obama. They would chortle at how Biden, like an elderly uncle at Thanksgiving, would launch into extended monologues that everyone had heard before.