The Star Trek Short Takes episode "The Trouble With Edward" focuses on H. Jon Benjamin as the mad scientist who sets Tribbles on the path to becoming an official enemy of the Klingon Empire
He talked to SyFy about the part:
"We didn't do a ton of backstory before shooting it," Benjamin explains. "But I talked to the writer [Graham Wanger] and there was a conversation about how he got there. Was it like nepotism? Is he like barely a scientist? Or is he just of dubious ethics? Or an outsider and nobody liked him? I think we landed on the latter. Like, I think he might have some basis in real science and maybe some real credentials. But, he's a bit of a lunatic."
In one scene, right before Larkin injects the tribbles with whatever genetic cocktail he's cooked up to modify them, he seems to be briefly sporting an ominous black vest and one of the all-black Starfleet badges usually worn by members of the clandestine organization Section 31. In essence, for one moment, it's like Larkin raided the closet of Captain Leland from Star Trek: Discovery. Later in Trek canon, the tribbles end up being a huge problem for the Klingons. (In DS9, Worf said tribbles were declared an enemy of the Empire at some point.) So, did someone in Section 31 plant Larkin with the hopes that he would act crazy and create new alien pest species?
Benjamin isn't ruling it out. If someone were pulling Larkin's strings, it would certainly explain how he got on the ship.
It's a fun episode that features a young captain's first command going thoroughly off the rails. But the real weirdness happens after the credits. The bonus scene is a commercial for Tribbles breakfast cereal. Self-replicating, plump, and very hairy:
The cereal comes in three repugnant flavors, and features a Poochie-style mascot:
You can catch up on the series at CBS ALL Access.