Everyone's focused on Helly. What about Mark?
I think the anticipated reaction for this Episode would be "Helly is actually Helena," so what if it's a misdirection to who is ACTUALLY the replacement?
That's right: Mark S.
Mark has changed almost more than Helly after coming back from OTC. While Helly and Irv appear more subdued afterwards, Mark is showing way more attitude to Milchick than he ever did in Season 1.
Like seriously, this is the last time we see Milchick and Mark directly interact before this episode:
Obviously you could chalk this to him learning about Gemma, but watching Season 1, he's just so much more noticeably forthright and unafraid. He kind of resembles Helly when she first woke up.
What if this is because he successfully got reintegrated before coming back to work? It would combine innie & outie memories and render the Severed elevator useless - Mark would be both his innie and outie on the outside world AND the Severed floor.
Reintegration disarms Lumon of their only weapons - the Severed elevators/doors. That would be why they're so against it.
It's why he went straight to Wellness but took a couple wrong turns along the way and looked confused - His innie & outie memories are both present. I think in future episodes, we'll learn what happened before each person returned to work, and Mark's story might end in reintegration.