NCIS: Origins Creators Reveal Key Mark Harmon Detail That Will ‘Destroy’ Fans’ Hearts

NCIS and NCIS: Origins just aired their first-ever crossover episode on Nov. 11. The crossover featured the return of Mark Harmon as Special Agent Leroy Jethro Gibbs, a role he played for 19 seasons on the original NCIS series.

In an interview with Entertainment Weekly, NCIS: Origins creators David J. North and Gina Lucita Monreal are dishing about what Harmon seemingly forgot about his iconic character. In the crossover episode, Monreal says the journey through the NCIS timeline focuses on “a cornerstone of [Gibbs’] personality,” a key aspect being his “steadfast dedication to victims’ advocacy, which at times can verge on obsessionGibbs was also known for his famous rule, which is, “When the job is done, walk away.” Monreal said Rule No. 11 is “central to this episode,” and Harmon, in a cameo in the crossover, is seen reciting it at the end of the Origins portion of the two-part episode. North confessed that hearing Harmon say the rule aloud made him laugh. He added that when he told Harmon about the scene, Harmon told him something that “fans will get pissed off about” that could even “destroy some fans’ hearts.