This is how I think about the ending, about Dark. Based on my own theory.
When we died, we saw Celine and Damien. They asked us to take our body so we accepted. But it was not them, it was Dark.
They’re baits made out from Dark to trick us and take our body. They’re not an actual Celine and Damien. It’s fake.
Those two and Dark is not a same person.
Dark is Dark. Dark is not anyone else.
so mark linked this on his twitter. guess its canon.