The metaphysics here get confusing, especially as Alan and Nadia’s timelines intersect, but I’ll try to dissect it all. Once they’ve returned to the original “loop,” both Alan and Nadia somehow end up within the other’s original night. Except in this version, the other is completely oblivious to the machinations of the universe. Alan is interacting with a loop-free Nadia — the same Nadia who slept with Mike all those episodes ago. And Nadia is interacting with a loop-free Alan, the same Alan who leapt off a building. They’ve ended up here because, well, this is what their task has been all along. Nadia had to stop Alan from killing himself. Alan had to stop Nadia from getting hit by a car. The mission is: Save each other.