I just wish that Bioware had coded Sebastien's dialogue and Hawke's options towards same a bit better, particularly in terms of playing a mage. Particularly during that act 3 quest where they're going on about "These mages are out of control!" and there's no option to remind him, "Dude. Mage. Who has saved your arse more times than anyone can count and actually takes down rogue blood mage arseholes, you prick."

I never see Carver and Merrill together, so I'll have to see what that dialogue is like, but to me ... I dunno, it clinched it for me when he turned up at her house to try to prod her outside to get some air. Generally when he worries about someone and interferes in their life, he either waits for them to come to him, or he does it clandestinely and denies it later. That seemed like an excuse to go visit her and I always kind of imagine that after her chat with Hawke, Merrill turns up at the Hanged Man going, "...Sorry." and things progressing from there. There may be fic one day.