I like Astarion for thirsty reasons, even though I sometimes feel like I'm invading LGQTB spaces when I romance him. That might be a me problem though.
However, I also like him because the man is a walking representation of the selfish will to live that any decent player must have. Not only is he enjoying his tadpoled predicament as much as a BG fan is, after decades of draught, but physically he is the embodiment of the best and the worst that the tadpole has to offer: awesome powers coupled with bloodthirsty violence, childish glee (like a baby tadpole) at psionically controlling others (like a grown-up illithid, but also just like the player who is in control of all the characters). The scars on his back, Cazador's "poem", are in concentric circles that look both like the marks that a giant tadpole would leave, with their little concentric mouths, and like a target (because we all have targets on our backs). And he's sad at the idea of losing the tadpole, because that would mean he will lose the ability to stand in the sun, just like getting rid of the parasite would mark the beginning of the end of the main quest, in-game.
He's a terribly handsome representation of the player's ID and that's why he's so popular.
