Frustratingly, given some thought, I could be any number of things. It's probably easier to list some categories I'd have to fit under, and see what is left over as a common denominator.
Independant - I'm not one for the military, or to eagerly bow to orders.
Stealthy - I'm not really a brute force kind of guy.
Secretive - My intentions are my own, and it's far easier to listen in on things if people don't know you have a predetermined opinion on things.
My thought, from this, would be a bard/vagabond/rogue/mercenary type of thing.
Vagabond/Bard: I prefer not to work FOR anyone if I can help it, as it puts high levels of limitations on what one can and can't do. That being said, I do need a dayjob, and music back then was well-valued. I'm a singer, ocarinist and guitarist in life, so I'd probably be the stereotypical vocal/lute combo. I'd travel a lot, and I love to tell stories - and where else but your local tavern to exchange music/stories, and listen in on rumours.
Rogue: I don't generally tell people my intentions, and have a tendency to eavesdrop - though never on personal things, or things people would specifically not want me to hear. I tune those out. I personally can pick pockets, pick locks, move silently/hide, and I'm more of a sneaky rapier kind of guy (being an epeeist) than a long-sword head chopper.
Mercenary: Well, not really being just a thug, I'd be more like the A-Team/Leverage type deal, choosing the jobs that I agree with morally. Why else would I avoid working for someone other than to do things on my own terms?
So my thoughts are that I'd be a secretive vigilante type. Yes, I'd be batman.