Michael D’Antonio never planned to release the recordings of his interviews with Donald J. Trump. The intimate conversations, which totaled five hours, were a research tool for his 2015 biography of the real estate mogul.

But something changed. A year later, Mr. Trump decided to run for president. And Mr. D’Antonio was deeply alarmed by the kind of campaign that Mr. Trump decided to wage. So a few weeks ago, the biographer allowed me to listen to the taped interviews.

Those recordings, which capture Mr. Trump in unusually candid, searching and unguarded ways, are the basis for a special two-part episode of The Run-Up. In both, Mr D’Antonio and I explore Mr. Trump’s emotional life, pyschology and behaviors, relying heavily on Mr. Trump’s own words from the tapes.

The recordings reveal dimensions of Mr. Trump we rarely see. He describes his lust for fighting in high school. He revels in the first time his name was mentioned in a newspaper. And he acknowledges a fear that the adoration of strangers, a sustaining force in his life, may someday fade away.