In a standoff with Olivia, she tells Athan how much she hates him and how much she's hated having to follow The Witness. Thing is, though, Athan has one final surprise. This whole time, that person we've seen stalking everyone in the mask and giving orders - it's been Olivia. This is news to her, but she realizes, she's now doomed to go back and trick HERSELF into all of those steps. That is some serious re-watching, team.