We heard some noises outside on the front porch that sounded like cats. At first I assumed this was just Mama, who is a nice feral cat that lives on the porch... But it was actually this guy, who let himself in the second I opened the door.
He's very curious and seems like a sweet boy. Spent the next hour or so wandering around inspecting everything as if he was buying the house. I put the other pets in our bedroom before opening the door, as they tend to spaz out in these situations... But one just mostly followed him around. They seem to get along fine.
No collar. Not sure where he came from. Probably fairly young. Definitely in good health, but who knows about fleas and worms and stuff.
This is almost exactly how my first pet found us, except he was seriously injured and didn't come in on his own. He just appeared on the back porch and stared at the door until we went out and got him.
Anyway, hopefully this guy belongs to someone and we can find them, cause I don't think I can handle a fifth pet.