Part ofStar Trek’s classic introduction to Tribbles inStar Trek: The Original Seriesseason 2, episode 15, “The Trouble With Tribbles”, was set up byStar Trek: Discovery. In “The Trouble With Tribbles”, Captain James T. Kirk’s (William Shatner) USS Enterprise crew meets Klingon Captain Koloth’s (William Campbell) crew on Space Station K-7. Instead of attacking the station, the Klingons claim to want shore leave.A Klingon plot to sabotage the Federation settlement on Sherman’s Planet is unveiled and subsequently thwartedwhen an outbreak of mass-replicating Tribbles consumes a shipment of poisoned quadrotriticale grain destined for the colony.
Star Trek: The Original Series' incident on K-7 alerts Kirk to a very important fact:Klingons do not like Tribbles, and Tribbles do not like Klingons. That mutual hatred points towards the true mastermind behind the poisoned quadrotriticale: Arne Darvin (Charlie Brill), assistant to the Federation Undersecretary in charge of agriculture. Tribbles don’t seem to like Mr. Darvin much, leading to the correct assumption thatArne Darvin is, in fact, a Klingon spy.This explanation worked in theTOSdays when Klingons appeared more human, but asKlingons became more alien, a better explanation for Darvin’s appearance was needed.

Star Trek: Discovery Set Up TOS’ Classic “The Trouble With Tribbles”
Star Trek: Discoveryprovides a retroactive set-up for Arne Darvin as a Klingon spy inStar Trek: The Original Series' classic episode, “The Trouble With Tribbles”. About ten years beforeStar Trek: The Original Series,Star Trek: Discoveryseason 1’s Lieutenant Ash Tyler (Shazad Latif) is, like Darvin, revealed to be a Klingon spy who has been surgically altered to appear human.Tyler had once been Voq, the Torchbearer for Klingon leader T’Kuvma (Chris Obi), who dreamed of uniting the Empire. After T’Kuvma’s death, Voq is willing to sacrifice “everything”, and is thus transformed into Tyler.
The truth of Ash Tyler’s identity as Voq is revealed inStar Trek: Discoveryseason 1, episode 11, “The Wolf Inside”.

Star Trek: Discoverydepicts Voq’s transformation into human Starfleet officer Ash Tyler as a painful, irreversible process. WhileStarfleet can transform humans into alienshumanely using short-term DNA manipulation, the Klingon version of the same procedure, called choH’a', is brutal and invasive.Klingon physiology is so different from humans', with multiple redundant organs, that Voq’s bones and internal organs were broken down and reconstructedbefore the memories of a very real Lieutenant Tyler were overlaid with Voq’s. To pass as human, Darvin must have undergone the same terrible procedure.
Star Trek: DS9 Explains What Happened To TOS’ Klingon Infiltrator
Arne Darvin Is Still Passing For Human In The 24th Century
The fate ofStar Trek: The Original Series’Klingon infiltrator, Arne Darvin, is explained inStar Trek: Deep Space Nineseason 5, episode 6, “Trials and Tribble-ations”. When Captain Benjamin Sisko (Avery Brooks) and the USS Defiant crew pick up the Bajoran Orb of Time from Cardassia Prime, Arne Darvin falsely presents himself as a Federation citizen trapped on Cardassia after the Cardassian-Klingon War broke out.Darvin plans to use the orb to get revenge on Captain Kirk by time traveling back to that fateful day on K-7and planting an explosive Tribble among the lot.
DS9’s Star Trek: TOS Crossover Pointed Out 2 Weird Things About Klingons
In Star Trek: Deep Space Nine’s crossover with TOS, Michael Dorn’s Worf knows two weird things about Klingon history that deserve explanations.
Like other actors who reprised their roles asStar Trek: The Original SeriesKlingons inStar Trek: Deep Space Nine,Charlie Brill returns to play Darvin in “Trials and Tribble-ations”. Because Arne Darvin had failed so spectacularly at executing the Tribble plot to take Sherman’s Planet, the Klingon Empire refused to take Darvin back, andthe Klingon operation that transformed Arne Darvin into passing for human in the 23rd century hasn’t been reversed.The same is true for Ash Tyler inStar Trek: Discovery, who abandoned the life he knew as Voq and joined Starfleet’s Section 31.