There's something in the EA that's very easy to miss - I'm not sure what exactly triggers it, but it happened for me when I was playing as a solo character after the 3rd dream. At some point when you go to rest Shadowheart will appear at your camp saying that she's hearing voices that are telling her to find you, and if you pass a wisdom check using the tadpole you can read her thoughts and you can tell that the voices are not coming from her tadpole. At that point you can either agree to let her stay, or if you don't then she'll attack you.
Obviously this event can't happen if Shadowheart is already in your party, but I'm not sure whether it's related to being a solo playthrough or just not having Shadowheart in particular or not. I think it's probably related to the dreams but I'm not 100% sure.
