I've only been in EA for about three months now, so I haven't had much chance to explore many character options with regard to romance. My initial character was something different for me: a tiefling warlock who was more neutralish than my normally good characters. Since I needed a rogue in the party, I thought it would be a good chance to test out Astarion.
I almost didn't continue with that, since he seemed like a bit of a whinger to begin with, however, he quickly became more charming once he warmed up to my character. While I agree that the depraved, hedonistic vampire is a very widespread sterotype, there were several suggestions that there was more to his character than that.
I actually found it kind of sad that he had only ever been able to feed on rats, and that he seemed so surprised and grateful when the PC lets him feed on them. Plus, when he reveals that Cazador's physic link allowed him to control Astarion like a puppet and make him do things he didn't want to do, I found that quite horrific (as one does with mind control). It makes me wonder how many of Astarion's predilections are his own and how many are due to being Kilgraved by a sadistic master for two centuries. That would be enough to traumatise anyone.
In addition to that, the fact that he seems to: place so much importance on whether the PC (and other party members) trust him or not, like when you refer to having each other's backs, and approve when you help out others in a similar situation to his (Karlach) suggest a glimmer of hope for him. I would like to think that, with the appropriate emotional support, he might be able to recover from his trauma somewhat. Becoming good seems too unlikely, but maybe reaching a more neutral outlook might be possible.
Or maybe I'm just a hopeless romantic and wish everyone could be saved, even when they can't.
Other than that, I thought my new druid character would end up hitting it off with Gale, but despite having extrordinary approval from him, she never got some of the interactions/scenes others have mentioned here. I'm not sure what she missed doing (other than him ).