I was climbing with a group of experienced climbers, plus one who had very limited climbing and no belaying experience. During the relaxed evening I taught my friend how to belay with a gri-gri whilst ensuring he was supervised by an experienced climber every time that I wasn’t immediately next to him. At the end of the session I agreed to quickly top rope a route to remove the crabs we had placed on the fixed gear. As it was a very easy route and I had developed confidence in my friends belaying, I let him set up the gri-gri without my input other than a cursory glance and belay me independently of others. As I reached the top of the route an experienced friend noted the gri-gri had been threaded the wrong way and stepped in to get the dead rope on a different belay device and removed from the gri-gri. Near miss