The novels sort of ruined that for me... Dukat is actually a torturer and rapist.
The novels are not canon, so there's no reason why they should ruin anything for you. The writers can (and often do) come up with all sorts of crap.
Of course, my policy is: if I like a book, I recognize it as my personal canon, if I hate it, I reject it.
I know I won't be reading "Fearful Symmetry", since I know what Dukat is supposed to be like in that book, and IMO that's utter rubbish and so out of character it's ridiculous. Good writing is making characters do only the things that make sense for their characterization.The author's idea of characterization seems to be "well, he's eeevil, so he'll do all sorts of eeevil things, right?" Um, no. That's like writing a novel about, say, Tony Soprano or Vic Mackey, and deciding "he's not bad enough, let's make him a child molestor". I mean, come on.