I multiclassed Astarion as a 4th level Thief (for the extra bonus action), and then gave him 8 levels of fighter.
He's pretty amazing. Four feats, bonus actions, extra attack. He currently has an armor class of 25 just walking around, without a shield. Two hand crossbows. Really, he keeps pace with Lae'zel's damage output, easily, and I can't recall the last time he failed a lockpicking roll.
I have the sneak attack on "ask," so I get it something from it pretty much every turn, and even on opportunity attacks.
Between him, Lae'zel, and my main character, the game actually feels way too easy. I also have Shadowheart in my party, but she functions more as support.
