I knew this guy who vanished for a day and came back a completely different person. I'm convinced he was replaced. I told my coworkers, but they just laughed it off — said who knows what happened to the guy, people go through stuff. And sure, I get that people can change after something happens to them. But it wasn't just his personality. Even the way he looked at you was different. His expressions, everything. It got to the point where it was creepy being around him, and I eventually just left.