One of my first clues was what he said if you take him to the ball. He mentions how much he loves courtly intrigue, and if you ask where he saw that, he says something to the effect of, "Erm, ah, well, um...FADE! Definitely fade!"
Of course it was. 
Or going over the art of hit and run tactics with Sera, or some of his banter with Cole. My poor roommate's Lavellan has been reduced to crying on best friend Dorian's shoulder:
Lavellan: (Sighs) Dorian, tell me I'm pretty.
Dorian: Were I interested in such things I would take you in a manly fashion.
Lavellan: Because I'm pretty?
Dorian: Yes, because you're pretty. Now may I please continue reading? It's rather distracting to have you moping and Cole skulking around trying to fix it.