@Bubbachino So, if I understood correctly, Vecna was partly lying. Marley really did die, but it wasn't him who brought her back, but rather the Upside Down itself, perhaps of its own volition. Now she's a kind of hybrid, part human and part Upside Down, with limited control over some aspects of it, something Vecna clearly sees as a threat, right?
Would it also be correct to say that the physical symptoms she's been experiencing (vomiting, fever, fatigue) are her body's way of adjusting to this connection, trying to balance the system whenever her Upside Down side becomes too active?
And if there's only one Marley, what exactly are the versions she sees, the one in the mirror at the mall and the one that helps her in the Upside Down? Are they projections, memories, or something completely different?