First playthrough I never got Dorian's personal quest, but at the end he kept saying he only had one friend left anywhere so he was staying put. (I was confused)
I just did his personal quest last night on my second playthrough, and wow.
I think based on personal quests, Dorian's and Blackwall's are my favs. Which also makes them my favorite companions.
Just popping into the Dorian thread to finally show my appreciation for his awesomeness since I finally got to know him a little better!
(although so awkward talking with him as a f!Quizzy, since the VA for Dorian so outclasses either of the female Quizzy VA's (they are both very flat))
(and Dorian in the Grey Warden battlemage Armor.....*woof* as Sera would put it)