Micah Bell has always been salty over Arthur because he had a better relationship with Dutch and that just made him mad he thought Arthur was just a rat of rat that didn’t deserve. No praise. He had that stupid black lung. That’s all he was a stupid black lung
Watching Arthur and Dutch talk, he mumbles “He’s a rat.” You looked over and he noticed. You don’t know why but something just snapped with you and now everything made sense. He was the traitor he had been a Pinkerton.