NCIS fans will be ‘pissed off’ to learn Mark Harmon doesn’t know this about his character Gibbs, Origins co-creator says

Mark Harmon played Supervisory Special Agent Leroy Jethro Gibbs for 19 seasons on NCIS. Forgive him if he’s forgotten a few things along the way.

Speaking to Entertainment Weekly about the flagship police procedural’s recent crossover with its first prequel spinoff, NCIS: Origins, however, co-creators David J. North and Gina Lucita Monreal say that exactly what Harmon’s forgotten about his beloved character may just be unforgivable.

Monreal says the franchise’s first-ever crossover through time explores “a cornerstone of [Gibbs’] personality.” Namely, his steadfast dedication to victims’ advocacy, which at times can verge on obsession. All this despite one of Gibbs’ famous rules: “When the job is done, walk away.” Monreal describes rule No. 11 as “central to this episode,” and Harmon himself recites it in a special cameo at the end of the Origins half of the crossover.

Hearing this particular rule spoken aloud makes North laugh. He confesses that when he brought it up to Harmon, he told the producer something that “fans will get pissed off” about, something that may even “destroy some fans’ hearts.”

“We were in the sound studio doing Mark’s voiceover with him the other day,” North recalls. “I was talking to him about what this is in episode 5, how so much of it is based on rule No. 11, ‘When the job’s over, walk away.’ And he said, ‘Man, the fans walk up to me nonstop and ask me about those rules.’ I said, ‘Do you know any of them? Do you know one of the rules?’ And he goes, ‘There’s one about a knife.'”

North and Monreal chuckle over Harmon’s relative ignorance about what has become an integral feature of the series; indeed, an institution within the NCIS-verse.

“If it feels like you’re being played, you probably are.” “Bend the line, don’t break it.” “Never mess with a Marine’s coffee if you want to live.”

The senior naval police investigator’s unofficial guidelines to being an ace agent were first referenced on the very first season of NCIS. Fan-favorite wiseacre Tony DiNozzo (Michael Weatherly) suspects they originated from Gibbs’ days in the Marine Corps, while others sarcastically crack that he just makes them up as he goes along.

But by Harmon’s final days on the series’ 19th season, he’d spouted at least 40 distinct pearls of wisdom that’ve become so legendary within the franchise that characters across all six spinoffs have invoked them during their own investigations

Last Tuesday’s NCIS/Origins crossover began on the prequel with a grisly train accident that wipes out a car, killing its driver. The tragic accident is revealed as a sinister crime, for which the members of an entire town are suspected. A wrongful conviction proves haunting enough to follow the NCIS team to the present, where they seize on the chance to solve the case once and for all when a prison break puts it back on the front page.

Gibbs may have stepped away from NCIS in 2021, but he’s remained a constant force within the franchise, providing the voiceover narration to new Origins episodes each week. Harmon finally reprised Gibbs in the flesh at the beginning and end of the crossover episode, “Funny How Time Slips Away.”

“Thirty years go by faster than you think,” Gibbs intones in his typically commanding manner at the outset. “The details get fuzzy along the way, but the victims, the victims are hard to let go of. Back then, I thought maybe it would help to carry them with me. I cut out their pictures and stuck them in my notepad. When it comes to the job, people tell you to do the opposite; they tell you to lock them away, compartmentalize, they call it.”

That’s the exact quality Monreal identifies as a “cornerstone” of Gibbs’ psychological profile. The question then became, “How are we going to visualize that?” Then came the idea of showing Harmon’s younger counterpart on Origins, Austin Stowell, cutting out pictures from recent cases, and of making rule No. 11 “central to the episode.”

Over the years, Gibbs’ various rules have been shown in writing — Harmon’s own distinct handwriting, which also made a cameo on the crossover.

“He handwrote all of those rules, so he had to write them like 10 times each,” Monreal explains. “He has beautiful handwriting. Very unique penmanship that we’ve seen on the original NCS many times. So we wanted to match it here when we saw the rule box, and he was game to write all those rules.”

After the true perpetrator in the train killing walks free at the end of “Funny How Time Slips Away,” Gibbs notes he “did my best to abide” by the rule to always walk away. “But in the end, it’s easier said than done,” he somberly says.

For the viewers who were thrilled by this novel crossover, NCIS star Wilmer Valderrama previously told EW that there’s much more in store.

“There’s gonna be some major surprises. There’s gonna be some nostalgic surprises, and we have a lot of big episodes,” Valderrama shared.

NCIS and NCIS: Origins air on Tuesdays as part of CBS’ “All-NCIS Tuesdays,” and stream the following day on Paramount+.