Having played through D:OS2 3 times and having had every party member around, I absolutely fail to see how Astarion resembles Sebille in any way at all. One is a narcissistic, sadistic, selfish and arrogant prick who is the very definition of Chaotic Evil in my book and has no redeeming qualities (being fangirl bait doesn't count), having been an utter scumbag even prior to his enthrallment - having recently replayed NWN2, I do find him somewhat similar to Bishop in how he carries himself and reacts to things, apart from the obvious difference in pompousness and the level of snobism, and another was enslaved as a child and brought up to be a magically controlled killer who managed to escape enslavement and is genuinely regretful of what she had to do but had no power to oppose it, and her storyline is that of revenge AND redemption.
I'd take Hexxat over Astarion in a heartbeat.
But Hexxat (pardon the pun) sucks. Out of the four Beamdog-added mainline companions she's probably the blandest? I could tolerate Neera, found Dorn just slightly aggravating and was only mildly irritated by how his quests in BG2:EE were written with only an evil character in mind, and Rasaad... fine, I suppose she shares the blandest title with Rasaad. But she neither had any particular involvement with the story (granted, none of the EE crew had, with the old three mostly getting the benefit of the doubt on account of being in the first game also) nor was really useful as a party member, forcing you to either wear that stupid shroud which gimps her significantly or only be doing anything important outside at night. Good luck doing all of Suldanesselar after the sun sets.
