Among You: Watching a World End, Book One of the Shattered Worlds series

Fred is a man on a secret mission - sent from an advanced parallel universe to document the coming collapse of another Earth designated 16-J. When a catastrophic disruption severs Fred's way home, he finds himself truly alone in the dysfunctional society he was merely meant to observe. Violating the rules, he illegally tracks down familiar faces that aren't quite his friends to stave off isolation. But his recklessness may expose the dark truth of 16-J's fate...and his role in sealing it.