Don't forget the hate Dorian gets. "He condones slavery" I read recently on Tumblr (a rare visit I assure you) that some people are stating that if you like Dorian than it's because you condone slavery too.
I totally regretted that visit when I read someone's "lovely" headcanon of characters murdering Dorian.
There is a school of thought that some people think DG put that in there as Dorian's "flaw," because really, he doesn't have any other than that... haha... Seriously though, unless you just don't jive with Dorian's personality, he doesn't actually have any major character flaws. While I adore Fenris, he has a nasty streak that comes out, especially when he talks to Merrill.
The meaningful thing to me is that he is willing to consider it and have a discussion, which is not something that many people are willing to do when confronted with ideas contrary to their upbringing.
I can really appreciate Dorian's approach to the conversation, which is intellectual rather than emotional. He is discussing slavery as a concept, and although he does reference the treatment of them briefly, he doesn't really delve into what it means to be property, which to me is the key issue. Unfortunately for players, the conversation in the game is woefully inadequate to discussing the issue in full, and the dialog options available to the PC are also emotional, rather than intellectual, so there can't really be a productive conversation in that sense.
Cole: Dorian, what's a slave?
Dorian: Festus bei um canaverum!
Cole: But you said I could ask questions!
Dorian: That's true. Just... go ask the Inquisitor this one.
IQ: Thanks, Dorian... (Sigh.) Cole, very basically, a slave is a person that is owned by another person**. They are property. Some may be treated well, and some may be treated poorly. Some people may get captured and forced into slavery and some might sell themselves into it. In the end none of that matters. Every aspect of their lives is controlled and they have no freedom. If a master wants to abuse his slave there are no consequences for doing so. That is what a slave is.
** Is that so hard? It's not a deep concept.
Dorian rebelled against control of his own life. It is so frustrating that he can't see how contrary that is to his views on slavery and I want to make him SEE that. Honestly, I think they should have left it out of the game altogether for the level of frustration it engenders. Not that a more detailed conversation would change Dorian's opinion, but the options are SO very limited that they seem almost pointless.