Oh, they can *all* be 'redeemed', ie. Follow the 'Good' path. Astarion in particular will tick that box for the ladies. He fits that 'he will change for me and then he's perfect' fantasy perfectly.
By 'all' I mean the Origin characters. I doubt you can lead Minsc unto an evil path, or Minthara on a good one.
Actually Minthara becomes very vulnerable to the player if you sleep with her in act 1, and if you manage to save her from execution and break her out of jail she'll be a bit of an outcast from the cult of the absolute...at that point it's just her and her massive crush on your character. I don't doubt she could be turned if you were so inclined...much as you can turn shadowheart to evil, you can probably turn Minthara to at least neutral if not good.
