If your PC is looking in the right direction when you hear "Connor No" you wll see a person (presumably Connor) go up in a blaze of fire. The first time I went through I didn't see him, but the 2nd time I was looking the right way and I did. It's easy to miss though. That's what happens if Connor is alive but unpossessed.
I went through that section a couple times, once I actually got to hear part of a conversation between Connor and that demon, but I opened the door and the dialogue got interupted by the "CONNOR NO!!!" I tried to replicate it but never again got that dialogue which I assume would explain what was going on there. Without that dialogue it seems so wierd and out of place, but I *think* what was going on was the demon that was denied connor could now get to him thanks to all the rifts.
