The innies of Lumon’s Macrodata Refinement department.
"Innie" is a term used for the “work-life” counterpart of people who undergo the severance procedure, which is a procedure in which people can surgically “sever” their memories between work and home, creating two different “selves.” Though they are most often used for work, they can also be used for avoiding difficult experiences in general — such as when senator’s wife Gabby Arteta used an "innie" to give birth.
Innies awake after surgery with general knowledge, such as how to talk and walk and the existence of Delaware, but no memory of who they are. Their entire lives are intended to take place inside a certain area, as the severance chips are spatially triggered. For Lumon’s MDR department, this means employees “wake up” in the elevator coming down to the severed floor with no memory of sleep or rest, over and over and over again. They know nothing substantial of their outie selves — their last names, where they live, if they have a family — and never see the outside world. All they do is work — literally. This also means that retiring or quitting is equivalent to death.
As people under these conditions would be understandably inclined to revolt, Lumon Industries has specific ways to control both innies and the outies bringing them to work. For example, innies are kept working with incentives, such as finger traps, caricatures, and waffle parties. They are also heavily punished for rebellion in the Break Room, where they are forced to recite a prewritten apology until they believe it and implied to be tortured in ways that leave less of a mark. (After Mark S. is sent to the Break Room in S1:E2, Mark has red marks on his knuckles, and in the Lexington Letter, Peggy K. is implied to have been waterboarded.)
For both of the aforementioned incidents — and for nearly all incidents leaving a visible injury (excepting Helly R.’s suicide attempt) — Lumon gives the outie a brief note with a false explanation on how the injury occurred and a gift card to Pip’s Bar and Grille. This keeps the outie from growing suspicious, leaving the innie trapped and letting mistreatment continue.
Lumon also cultivates a religious mindset worshipping Lumon founder Kier Eagan and prevents innies from unionizing by keeping them far from other departments. MDR doesn’t know how many departments even exist, and with those that they do know, Lumon further discourages contact through propaganda painting the other as dangerous.
Innies are also forbidden from contacting their outie selves and punished severely for attempting to do so. Mark S. references this when he tells Helly R. not to swallow a note for her outie, as “it’s Milchick’s job to extract the message from you. And when he asks how long ago you ingested it, I really can’t recommend honesty enough. It’s easier for you both if he knows which end to start from.” (S1:E3)
Some call the term “innie” purposefully infantilizing, and wonder if it could also be interpreted as a diminutive of “infant.” This is not without reason, as innies are more infant-like than their outie counterparts. They have no adult life experience — none of the baggage or wisdom of their outies — and, like abused children, live completely at the mercy of their caretakers who brought them into the world (in this case, Lumon) and control their realities. They are not only victimized by their employers, but also by their outies, who let a conscious self be created only to subject it to a torturous existence of eternal tedious work — all to make it easier on themselves. Like an abused child wonders about their parents, innies often wonder about their outies: what their lives are like and why they chose to do this to themselves. Mark S. asks Devon this question in S1:E9.
This is also seen in Petey’s description of reintegration — an underground procedure said to reverse severance and bring the two selves together as one. Allegedly because he didn’t follow Regabhi's post-op instructions, Petey suffers from headaches, nosebleeds, and flashbacks to his life as an innie as a result. He says this is because he has “two pasts” and the relativity is distorted: specifically, that his first day at Lumon is as far back as his fifth birthday. It is unclear whether this is a random coincidence or whether innies are similar to children on a neurological level.
It is also worth noting that MDR's innies gain consciousness for the first time alone and splayed out on a table, which creator Dan Erickson said was meant to "give them a sense of being 'born' into this world."