This is probably just arospec cope but I sincerely believe that that last scene would have been just as effective without Helly, if not even more so (if just in a different way).
Like yeah, Gemma seeing Mark suddenly abandon here for some woman she’s never seen before is high melodrama and all, but consider: Gemma looks back, disoriented and confused about why he’s still on the other side of the door, and he looks at her blankly for a few moments, considering, before simply walking/running back into the darkness from whence he came. End scene.
I’m not even posing this as an alternative to canon Markhelly, not at all. He’d still be considering her, it just wouldn’t be spelled out to the audience so incredibly obviously. Plus this way they don’t have to explain why she’s suddenly all the way over at the stairwell for no apparent reason. Also it serves to emphasize how wanting to be with Helly isn’t the only reason he’s not going with Gemma, he’s doing it for himself too, not to mention the other innies. I also just think it’d be really atmospheric and I love that shit.














