I thought Relenus was a place when I first heard it mentioned - as though it was a memory of what had happened at a particular location. No idea why I thought that.
Still, my favourite banter has to be the "wishing but wondering" conversation with Cole; Dorian comes perilously close to being sappy in public. After all the prodding about his father, it was nice to see a subject that Dorian was so happy to discuss, he didn't even object to the mind-reading (and mind-reading his thoughts around the time he was having sex, at that - compare that to his IB romance comments). And Cole comes across as adorably delighted when he sees how happy Dorian is - he even does the Spirit equivalent of a squee at the end!
Yes!!!! Solas is such an ass despite Dorian trying repeatedly to be friends.
I really liked the fact that Dorian goes out of his way to be friendly, unwittingly (or not?) playing the ambassador for Tevinter. I did cringe whenever he stepped on a landmine with Solas. You can't really predict what will set Solas off the first time through the game - Fenris and Anders were both grumpyguts, but you knew where their berserk buttons were, while Solas (along with Sera) isn't as straightforward. It was interesting that Dorian was changing tactics to try and lighten the mood, switching between joking and genuine intellectual conversation, but every time I head Solas' voice reply, my thought was "oh no, what's he going to get his head bitten off for this time?"
I wonder if Solas and Blackwall have the same problem with Dorian - that he's unashamedly true to himself and upfront about his past, despite a heritage that makes him a default "bad guy", while they're both hiding something terrible while in the role of pure-hearted "good guys"?
Although frankly, the Tevinter = slaves thing was never going to help Dori's case.