In the Star Trek: The Next Generation episode “Reunion”, we end up saying goodbye to three prominent Klingon characters: K’Ehleyr, K’mpec, and Duras. K’mpec had been slowly poisoned for months through trace elements planted in his bloodwine. He died believing that one of the two candidates for chancellor-- Gowron or Duras-- had been behind the poisoning.
What follows is one of the best episodes of TNG in my opinion-- full of the political intrigue that would later become a mainstay in DS9’s best seasons. A suicide bomber attacks during the Son’chi ceremony. We find out later that the suicide bomber was probably one of Duras’ men. Gowron goes to K’Ehleyr and tries to bribe her, and later threaten her, to use her influence with Picard to have Gowron named chancellor. He uses the words “K’mpec was stubborn too; he also refused to listen.” Makes you think he may have had a hand in the poisoning, doesn’t it?
Worf refuses to speak to K’Ehleyr about his discommendation, leading her to investigate the matter herself. When Duras realizes she’s been poking around, he confronts her, and she tells him what he’s discovered. So he kills her. Worf gets to her in time for her to name her murderer, and Worf goes over to Duras’ ship and avenges her death.
Later, in “Redemption, Part I”, Gowron says to Worf, “You killed Duras, and I consider that no small favor.”
But hooooold on a second. Duras may have died in disgrace, but we never got an answer to the question of who killed K’mpec. In fact, the evidence seems to point to Gowron as the likely suspect. And the Gowron we see later in TNG and DS9 is a manipulative political animal; I wouldn’t put it past him!
The entire Klingon high council is as corrupt as they come only giving lip service to the Klingon code of honour. Or at least that’s how Worf and Picard precieve it. I don’t think Worf ever really got Klingons. Too much human in him. A society as nihilistic as the empire, where you’re literally a failure if you don’t die in battle, you can’t really expect people to follow the rules. And the number one unwritten rule seems to be that all is honorable so long as you don’t get caught.
Although it’s never outright stated, the strong implication is that Duras most definitely did poison K’mpec. Gowron is many things, but he’s very in-your-face. He will use politics to cut down rivals, but he’s a fighter and he has no hesitation about attacking his rivals face-to-face. Even as a fairly old man, he’ll happily pick up a sword and start swinging with Worf, a master in melee combat who once won a tournament where the weapons are real and very deadly. Gowron is cunning, but he’s cunning within the context of Klingon honor. If he had assassinated K’mpec, he’d have sent a man to do so with a blade or phaser, not poison. (This is apparently accepted, since it involves pitting warrior against warrior, just in a dark alley instead of the battlefield.)
Duras, on the other hand would certainly use poison if it were easy. He has close contacts in Romulus with just that kind of expertise, and was more prepared to take advantage of K’mpec’s death - as if he knew it was coming sooner than anyone else had anticipated. Gowron is ruthless, but he has limits and a code of conduct. Duras does not, and that’s the main difference between them. Additionally, for all his violence and bluster, Duras is a great coward. He only fights when he believes victory is already won. It’s such a pity that he underestimated Worf, son of Mogh.
I didn’t get the impression Duras was a coward, but he was prone to impulsive short-sighted decisions. He killed K’Ehleyr for no good reason and was stupid or arrogant enough to think he could get away with it, when he should instead have asked her what she wanted and tried to buy her silence and secure her as an ally of sorts.
That’s not necessarily cowardly. The Klingons say such tactics are cowardly but we had ample opportunity to observe, even from Worf, that expedience beats honor on occasion.