No... not a long essay.
Angua does that much better than I do.
But I was listening to CoS during my commute, and this passage seemed to have new meaning after HBP:
"You can speak Parseltongue, Harry," said Dumbledore calmly, "because Lord Voldemort -- who is the last remaining ancestor of Salazar Slytherin -- can speak Parseltongue. Unless I'm much mistaken, he transferred some of his own powers to you the night he gave you that scar. Not something he intended to do, I'm sure ....
"Voldemort put a bit of himself in me?" Harry said, thunderstruck.
"It certainly seems so."
I can't help wondering if it's an obvious clue.