I'm listening to Sorcerers Stone on audio book. Have read the full series more times than I can count. But there are several things that I still don't get, one of which being this. Before you know the full plot, you are led to believe that Snape is demanding that Quirrell reveal to him how to get past whatever he did to protect the stone, (which is later revealed to be a troll.) But obviously we know that isn't the case.

In googling this, I didn't find a quick answer. I found someone theorizing that he knew Voldemort was inhabiting Quirrell's body, which I absolutely don't buy. Albus Dumbledore would have never left the castle if he knew there was a smidgen of a chance that Voldy was inside it. And Snape, being the spy he was, would have surely reported such suspicion to Dumbledore.

It just leaves me with more questions than answers, to this day. I'd love to hear theories as to what he is saying!