Captain Malcolm 'Mal' Reynolds is not a Captain, he is a Sergeant. They only call him captain because he owns the ship, and if you don't call him that, he gets agitated and starts shooting things.
Well, maybe he doesn't do that, but one thing is for sure: Mal runs a tight ship. In his world, the ship is his only refuge against the Alliance that has plagued him eversince he took them on as a member of the Browncoats (and lost).
Mal is an untrusting renegade, except when it comes to hsi crew. for them, he would give his life.
Mal lives only for his ship, his crew, and his freedom.
Mal: "If I'm your mission, Shepherd, best give it up. You're welcome on my boat. God ain't."