"he's Dresden's opposite in many ways, and yet in other ways they are very much alike."

Yes, yes, exactly! Thank you - it's always interesting to know what pushed a writer in one direction or another :)
I always wonder whether some of the secondary characters in some books seem to us fascinating because the characterization the author present gives the reader a sufficiently rich image of, say, Marcone or whether it's our interpretation of motivations of these admittedly already interesting characters and all the layers we add to the character while reading - that make these characters so appealing. And all we build up on these characters not necessarily stems logically from their image in the book they come from. 'Even Hand' convinced me that most of authors in this fandom have made very 'true to the letter' conclusions from the small amount of information about Marcone we were given in the novels.
And sorry for my rambling; English is not my first (nor second, nor third...) language, I tend to overwhelm myself while using it in writing.