Donald Trump is Kramer from Seinfeld

If the question had been a little less pointed — perhaps if it had been about immigration — Donald Trump might have resisted the urge to attack for more than a minute. But the first question of Thursday's debate on CNN was about Trump's temperament and it obviously got under his skin.

"Well, first of all, Rand Paul shouldn't even be on this stage," said a peevish Trump. "He's number 11, he's got 1% in the polls, and how he got up here, there's far too many people anyway. As far as temperament — and we all know that — as far as temperament, I think I have a great temperament. ..." Trump went on to brag about his accomplishments as businessman, entertainer and author and then concluded that, "... my temperament is very good, very calm."

Called out, as if he were an eighth grader on a playground, Paul responded with: "There's a sophomoric quality that is entertaining about Mr. Trump, but I am worried. I'm very concerned about him — having him in charge of the nuclear weapons, because I think his response, his — his visceral response to attack people on their appearance — short, tall, fat, ugly — my goodness, that happened in junior high. Are we not way above that?"

Remaining in character, or perhaps true to his genuine self, Trump gave the audience what it expected, saying "I never attacked him on his look, and believe me, there's plenty of subject matter right there."

To borrow a phrase from Trump it was bing, bing, bing and the GOP hopefuls were dragged into a verbal brawl punctuated by sneering commentary and unseemly boasts. Trump had baited Paul and received, in response, an opportunity to deploy his usual tactic of hitting back "10 times harder" (as he says) whenever he feels slighted. In his past life he had done the same thing to Rosie O'Donnell and Cher and Bette Midler, each of whom had criticized him and suffered when he responded. Now he was doing it to a United States senator who was standing almost beyond the camera's range on the debate stage.

In trying to understand this dynamic it helps to consider Paul's complaint about Trump's junior high school antics. In fact, as he picked on Paul and later George Pataki, Trump did act like a schoolyard tough going after the weakest kids in the crowd. Neither Paul nor Pataki is likely to play a significant role in the campaign as it moves forward. Paul enjoys fervid but limited support among Libertarian-minded GOPers and Pataki defies any attempt to explain why he's on the trail at all. However, as he focused his attacks on them, Trump revealed something important about the instincts that guide him. He was, in effect, picking on the most vulnerable -- the 98 pound weaklings -- even as he played nice with his steeliest opponent, Carly Fiorina.

Showing herself to be a tough cookie who, like Trump, knows the power that comes with taking offense, Fiorina went after him for his past remarks about her appearance and refused to back down even after The Donald said, "I think she's beautiful." She had Trump on the defensive and she did what she could to keep him there all night long.

Similarly, another candidate with a strong personality, Chris Christie, went after Trump with a reminder, to him and Fiorina, that most Americans aren't interested in their accomplishments. "They could care less about your careers, they care about theirs." Christie added, "Let's start talking about those issues tonight and stop this childish back-and-forth between the two of you."

As Christie chided his fellow Republicans, we could hear echoes of the quarterback who separates two angry teammates and implores them to stop their feuding for the sake of the home team. But while Fiorina was obviously one of the New Jersey governor's targets, it was obvious that the real object of his impatience was Trump.

Ever since he walked onto the field in June, Trump has used his well-honed skills as an advocate to bully the other kids. In the interviews I conducted with Trump for a new biography of him, he said this style comes naturally, and is as much a matter of instinct as a deliberate choice. He also painted a picture of his father as a similarly tough man who expected much in terms of respect. Trump's mentor at New York Military Academy would recall, "The father was really tough on the kid. He was very German."

Trump insists that his father, who sent him to be straightened out at NYMA when he was in eighth grade, was as loving as he was tough. There is no reason to doubt him. Similarly, I have seen Trump be kind and considerate in private settings. The trouble is that the private Trump is rarely on display and in his public person he often looks like a bully.

I am reminded of an episode of "Seinfeld" that included, as a storyline, the character Kramer's experience in a martial arts dojo where every one of his classmates was younger than 12. Week after week, Kramer dominated his opponents and even seemed to revel in his success. But eventually the youngsters ganged up on him and he was overwhelmed in a flurry of kicks and punches. As the defining scene of the program ended, Kramer was pinned like Gulliver beneath Lilliputians clad in white martial arts costumes.

In the second debate, Fiorina and Christie fought back against the big kid in the dojo and landed a few blows. Now the country waits to see if the rest of the kids join them in defeating the muscle-flexing giant in their midst.