What incorrect assumption does the group make about Darien in the novel, Unbreakable?

Darien was tasked with protecting the last disk, and he even tells the group that he is a part of the Legion or at least was closely associated with it. In the beginning he is made out to be a villain like all of the other ghosts but he’s the one that opens everyone’s eyes - just too late. Darien tries hard to protect the disk but fails to convince Kennedy that he is telling the truth about the shift. It’s his last words that let her and everyone else know that he was telling the truth and everything they have done has been to release Andras.