You know what reason Halsin gave me to stay with my group instead of going back to teh grove, where he belongs? He stays, because of me, he says this so suggestively, that I'm not talking to him anymore, apart from strictly story stuff.
I think by now, Astarion is the only companion, that did not hit on me (apart from Shadowheart, where I iniciated the flirt, because I wanted to actually romance her). I don't like Astarion, but he does grow on me for that simple fact.
Did I see you mention somewhere you are playing a Halfling?