So the big reveal, so to speak, in regards to Ethan just didn't make sense to me. If Ethan is just a walking corpse made of the mold, wouldn't that imply that Mia is the same? If I recall correctly, you damn decapitated her with an ax back in Louisiana. So if dying and being healed by the mold essentially results in being 'undead' in a sense, then they've both done so.

As such, how the hell did they have a child. Did the mold just, make one, or allow their reproductive organs to continue functioning?

Basically, it just doesn't make sense to me. If they'd instead gone with something like "The mold can only heal you so much over a period of time and too much is what leads to calcifying and actual death" it would fit. It would explain how each of the villains have died due to taking too much damage over a short period of time. The better your body adapts to the mold, the more damage you can heal from in a short time-frame.

Then, Ethan starting to calcify would make more sense as well. All the damage he's taken, the beating he's been through, having his damn heart ripped out. He's pushed his mold too far and he's breaking down.

I dunno, just... the whole "You're already dead and have been for 3 years" thing just rang hollow for me.