It’s easy to fall into the wrong world.
It happens most often to children. Their grip on reality is loose to begin with, and when their imaginations wander, sometimes body and soul will follow. I’ve seen it happen. One minute the kid is there, playing in the dirt and whispering to themselves, and the next they’ve slipped down into an Echo. You have a tiny window, maybe five seconds, where they go a little transparent around the edges; if you spot it in time and you’re fast, you can catch them. Otherwise someone like me has to go in after them, and that’s dangerous work.