When Tiah Joo Kim arrived at the Manhattan headquarters of the Trump Organization to pitch a hotel and condominium project in Vancouver, British Columbia, he expected the famous company with ventures across the globe to come with capacious offices and a staff of hundreds. Instead, he was led through a mere two floors with what appeared to be no more than a few dozen employees. “Lean,” Mr. Tiah, a young Malaysian developer, remembers thinking as he walked the halls.

The first stop was a conference room, where Mr. Tiah was required to sell his vision to the boss’s three oldest children. Only after securing their support did he advance to the inner sanctum, with its sweeping views of Central Park.

Mr. Tiah was not sure what to expect from the man whose face was beamed around the world through the reality television show “The Apprentice,” but the conversation that afternoon in 2012 was casual and warm. Donald J. Trump spent more time showing off a Shaquille O’Neal shoe and a Mike Tyson championship belt — prize artifacts from his display of sports memorabilia — than interrogating Mr. Tiah on the details of his business plan. “You’re a good-looking guy,” Mr. Tiah recalled Mr. Trump telling him as he gave the project his blessing.

Then Mr. Trump’s trusted lawyers and other top executives swooped in to play hardball — working alongside Donald Trump Jr. to negotiate the confidential agreements that would allow the Vancouver development to be branded with Mr. Trump’s name and managed by his company. The talks consumed 16-hour days for nearly a week, Mr. Tiah said, explaining: “It was tiring. They’re tough.”