“He never really had an off switch with his debater’s demeanor,” said Ted Ruger, who was president of the Harvard Law Review during Cruz’s third year. “We just realized that was the way a discussion with Ted was going to go. If you expected something different, you came away shaking your head.”…

“He came in with his right hand raised and basically kept it raised the entire semester,” said Alan Dershowitz, who taught Cruz in a first-year criminal law class. “Every year you see two or three students who you know are natural leaders. Everybody saw that with Barack Obama . . . Everybody saw that with Elena Kagan. There are students who come in with charismatic qualities who other people follow. He was one of them.”

While talkative and outgoing, he struck some classmates as nakedly ambitious.

As they were entering their second year in law school, Melissa Hart agreed to give Cruz a ride from New York, where Cruz was at the end of the summer, back to Cambridge. She didn’t know him well, but he sought her out after she had been given a prestigious award for first-year students.

“We hadn’t left Manhattan before he asked my IQ,” Hart said. “When I told him I didn’t know, he asked, ‘Well, what’s your SAT score? That’s closely coordinated with your IQ.’ ”