Author Note: One of three short stories I wrote to get a handle on River and Jayne before I wrote Acceptable.
River Is Scary
The others are scared of River sometimes. She's heard them think it, how she can take down anyone and everyone in her path and how she brought slaughter to the Reavers as if she was teaching them the meaning of the word. She's scarier still because she doesn't look like she could, the danger of her concealed.
She thought Jayne wouldn't be afraid. Jayne likes weapons and Jayne likes girls, so it was logical to think he wouldn't mind a girl-weapon.
She doesn't always live with logic though and that's the problem.
Jayne is used to being hurt and people taking advantage when his guard is down. He didn't see it coming when she cut him, but he sees it now and what's known isn't feared. What he isn't used to is hurt without reason (or reason apparent to him).
Jayne isn't scared of weapons. It's the crazy that bugs him.