okay, first off, awesome idea- personally I always enjoyed just, character studies. It's like my general obsession with creating worlds but no plots :/
ANYWAY. You'd need a few things for this-
stereotypes. you'll need them to help make this work right- your mercenary. the one with the morals in exchange for money. keeps his word and all that, and does NOT do certain things. he came most likely to get out of the business.
The Gentleman-pirate. okay, but that, i mean.. hmm. acts well in public, but very specific. you know. you make a deal with him and he follows it to the letter, no assumptions made. He's the man who you find kinda fishy but you wouldn't actually be able to find any evidence on him, yanno? He might not actually be here to turn around, but rather, to make a profit.
The generic scum. In this town, these guys would probably be the only ones who still rob and steal. everybody would look at them funny for giving their already dirty town an even worse name- they sort of kill the point to some extent.
you'd want a few poeple who HAVE killed, for a middle ground between the murderer and the normal baddies. like, they've shot a man and all, bu not on purpose, or under pain of death if they hadn';t. yanno

Hmmmm. a leader. maybe somebody who had originally moved to the town with his group awhile ago.
you could go a few ways- somebody who honestly wanted to change and who forces everyoen else to using scare tactics, or one of those poeple who always had a heart, just never any choices..
D:
yeah. i dunnno. I'm just idly tossing ideas :/