It’s hard to see it as a “betrayal”, but it technically is: Fives in season six of the clone wars.

It was heartwrenching to see how he was such a good guy was driven mad and then shot down, because he found out about a conspiracy that would’ve ruined his life had he survived.

It’s especially sad, since he could’ve saved trillions of lives if people had simply believed him.

Jacen’s transition into Darth Caedus was sad for me because of how much it went against everything he stood for. Jacen was the Qui Gon Jinn of the NJO and he advocated for valuing all life even those of the Yuuzhan Vong. Even after they captured and tortured him he refused to allow the dark side to corrupt him. Speaking of corruption he also didn’t want the Jedi order to become corrupted by the politics of the republic in the same way the old Jedi order did. All of his idealism was whipped clean by Denning’s writing and the killing of his own aunt.

I suspect many won’t think of the infamous Order 66, whether you know it or not, it was a betrayal... In both Legends (pre-Chip and post-Chip) and Canon continuities, the troops the Jedi trusted after three years, gunned them down. Whether by blind obedience or forced into a hypnotic trance.