Jayne Cobb never liked Simon, though not for the reasons most would think. Sure he thought the doc was a prig who was going to bring all sorts of Alliance based trouble down on them and his sister was one crazy psycho who once carved Jayne's ruttin chest open. But that weren't the real reason.
Most men, and women, thought Jayne was an idiot. The dumb muscle good for nothing but killing and lifting heavy cargo. They didn't stop to think how if he were such a fool how had he lived out on the Border Planets for so long? Sure Jayne didn't have books smarts, but he wasn't stupid. He lived on his instincts, the instincts that told him when the other son of a bitch was about to draw, where to stick the knife to kill a man, or when the trap was about to be sprung and the bullets start flying. Those were the instincts that had kept Jayne alive and those same instincts told him that Simon Tam was more dangerous than any of them on Serenity. He had no idea why, the man couldn't shoot straight, couldn't fight for worth a damn. But deep down inside something about Simon Tam scared Jayne.