Update! The player who previously worried that his choices didn't matter made a BIG choice today that pretty much altered the course of our campaign: He allowed the entity to possess him, protecting his crew and the rest of the party and ensuring they don't have to carry that burden. She agreed, in hopes that he would help her reconcile with the collective that previously expelled her, her real family. Once she regains her strength, she'll be able to manifest bodily. But she won't be an antagonist anymore (which is the biggest change of all- she was intended to be the primary antagonist for the whole campaign).