I feel like Shadowheart is one of the characters where you could push for either good or evil as you play the game. I don't get the feeling that Shadowheart is evil at all from the interaction. She's pragmatic, so she doesn't like to waste time when you have a ticking timebomb inside you, but she tends to dislike whenever you commit evil deeds and benevolent actions actually give her approval. The most evidence is if you sided with the goblins; she gets really upset for killing the defenseless. From what it seems like, Gale and Shadowheart are leaning more toward neutral, Wyll is more toward good, Astarion and Laz'rael are evil just based on their approval alone.