In the Watergate hearings, John Dean (now serving as a commentator on CNN) played the part of the heavy-hearted insider testifying against his administration out of grim duty. Mr. Sondland showed up wearing the smirk of a man able to imagine himself the toast of any room — even if that room was investigating an international scandal that he had a major role in.

Told that Tim Morrison, a national security aide, had referred to his actions as “the Gordon problem,” he cringe-joked, “That’s what my wife calls me. Maybe they’re talking. Should I be worried?” He grinned through rounds of exasperated questioning, through recollections of a cheerfully profane phone call with the president, through the memory of buying a “V.V.I.P.” ticket to the inaugural.

Mr. Sondland was the V.V.I.P. on Wednesday. But there were serious stakes, for the country and for him personally. He had already emerged as an offscreen figure in the hearings, described in phone calls and text chains, orchestrating the efforts to muscle political favors out of the Ukrainians.

He showed up in person as the defendant in the legal drama who refuses to be the fall guy. Beyond the bombshell explosions, if you listened closely, you also heard a series of clicks: Mr. Sondland handcuffing himself, one by one, to a list of officials attempting to stay out of the scandal.