Well if it were me I'd tear the vent open then go looking in there. Hell I'd even make my hand smell for good so it would bite and coil me then I'd grab it and pull it back, but that's me.

I'm just going to pray that he doesn't fall to the bottom floor through the vent because that would be about the worst possible scenario, other then that I don't want to think about it. All I can say is good luck.