 Mr. Trump, using an expletive, bluntly told Mr. Vance, you said some nasty stuff about me. The discussion that followed was described in detail by two people with knowledge of the meeting who insisted on anonymity to talk about a private conversation. Mr. Vance's next move was crucial. This was the first time that he was meeting Mr. Trump, and Mr. Vance needed the former president to like him or at least leave the meeting with an open mind.