When it comes to Severance Season 2, we know for sure that Lumon Industries never met a mystery it didn’t want to smother under corporate jargon and a board video call. And no puzzle is gnawing at the fandom’s brain quite like Cold Harbor. Mark S is apparently destined to finish this project, whether or not he has any memory of ever agreeing to it.By mid-Season 2 of Severance, Helly R has returned to the Severed floor against her will, Irving has vanished, and Mark is closer to remembering he has a wife who is very much alive. Well, at least in some capacity. And through all of this, Lumon’s higher-ups are sweating over Cold Harbor, insisting Mark is the only person they trust to complete this job. So yeah, no pressure at all. Now, what is Cold Harbor? Why is Mark at the center of it? And why does Ms Casey’s face keep flashing? Let’s unpack the theories.Why can only Mark finish Cold Harbor? View this post on Instagram Instagram PostCold Harbor is the first assignment Mark works on in Lumon, but in Episode 5, we enter panic mode. Mr Drummond declares that once Cold Harbor is complete, it will be "one of the greatest moments in the history of this planet."And that’s where the season starts to tie knots around Gemma/Ms Casey. Season 1 ended with Mark’s Innie discovering that his supposedly dead wife is very much alive inside Lumon, just that she has been repackaged as Ms Casey. And then her face starts popping up on the Cold Harbor interface along with the usual numerical data. That’s a sign this is all connected on Severance. Also, Cold Harbor is what Lumon uses to manipulate Mark on Severance. Want your MDR friends back? Want Helly reinstated? Want slightly fewer moral dilemmas? Finish the project, as if it were that easy!The numbers complicate things further. Lumon employees sort digits that evoke emotional reactions (dread, frolic, malice, woe), which align with the "tempers" touted by founder Kier Eagan’s cult. There are also progress bars on their work computers that are labeled WO, DR, FC, and MA.Does Cold Harbor refine these tempers? Modify them? Transfer them? Is Mark somehow altering Ms Casey’s personality? Or is Lumon using tempers to reconstruct people? That brings us to Theory Mountain.Top theories on what Cold Harbor is on SeveranceThe wildest theory is that Cold Harbor ties into resurrecting Lumon founder Kier Eagan. And the goats may be test subjects for its experiments. View this post on Instagram Instagram PostThen there’s Ms Casey. Mark’s Outie insists he identified Gemma’s dead body. So how is she alive? And if Cold Harbor is Mark’s project, is he reprogramming her, then? Or is it Ms Casey who is spying on Mark from the inside?Severance creators Ben Stiller and Dan Erickson say that they know what the work at Lumon is, but it’s not the "big twist" we expect. So, Cold Harbor may be about Severance's core question: what does controlling consciousness mean? Whatever Cold Harbor turns out to be, it defines Lumon. The goats know something. They have got to, right? The first two seasons of Severance are streaming on Apple TV+.