Through his first two hours of oral arguments on Monday, Justice Neil Gorsuch questioned every attorney who came before him with one exception: Neal Katyal.

Gorsuch's silence during Katyal's arguments is noteworthy, as the newest justice played the role of a happy antagonist throughout the rest of the day's hearings. Unlike during the Senate hearings on his nomination, Gorsuch was not shy about injecting himself into the various cases and controversies before him.

Katyal, who was arguing at the Supreme Court in Town of Chester v. Laroe Estates involving a zoning dispute, introduced Gorsuch at Senate Judiciary Committee hearings on his high court nomination. Katyal effusively praised Gorsuch last month as a judge who "displayed a resolute commitment to the rule of law and the judiciary's independence." On Monday, Gorsuch did not say a word when Katyal came before the Supreme Court.

Gorsuch waited until after five of his fellow justices asked questions in Monday's first case, Anthony Perry v. Merit Systems Protection Board, before piping up. But when Gorsuch spoke up in the case, which involves which lower court holds jurisdiction over a discrimination claim brought by a federal employee, Gorsuch did not hold back.

Gorsuch repeatedly questioned Christopher Landau, the lawyer for the plaintiff, and Brian Fletcher, assistant to the U.S. solicitor general, to point him to the statute at issue to make their case. Gorsuch delivered his questions and remarks with a persistent smile and drew laughs at times through the courtroom.

In answering another justice's question, Landau referred to a question from Gorsuch and said, "We're not asking the court to break any new ground." Before Landau could pause to take a breath, Gorsuch interjected, "No, just to continue to make it up."

Gorsuch's willingness to mix it up with attorneys on his first day did not impede the genteel demeanor he cultivated as a 10th Circuit Court of Appeals judge and put on display during his nomination hearings. The phrase Gorsuch proffered more than any other justice on Monday appeared to be "I'm sorry." Twice when interrupting lawyers and once when jumping in on Justice Sonia Sotomayor's line of questioning, Gorsuch apologized before proceeding to hurl questions at whichever attorney stood before him.

Gorsuch's jovial nature throughout Monday's hearings — frequently smiling in the direction of former law clerks in the courtroom and thanking his fellow justices for their warm welcome — made his approach to Katyal's appearance all the more noticeable.

Katyal is a former acting solicitor general of the Obama administration and has proven to be a leading foe of President Trump. Katyal is one of the lead attorneys for Hawaii in its suit against the Trump administration over the travel ban. Katyal also has been the target of criticism from the Republican Party working to advance Trump's agenda.

With several challenges to Trump's travel ban and executive actions on immigration hurtling toward the court, Katyal could have a starring role in the controversy's likely review at the high court. Gorsuch's interaction with Katyal on Monday may preview a relationship that could fall under a big spotlight later this summer when litigation on the travel ban is expected to arrive at the Supreme Court.