I'm concerned if, this late in the game, Harry's only reason for suspecting the Defense Professor is "just because he's the Defense Professor." It would seem that he has way too many excellent reasons to suspect Quirrell no matter what his title. The sense of doom. The fact that he was able to cast Avada Kedavra on a random guard. The fact that he carried Harry off on a disastrous plot to free Bellatrix Black. The fact that he happened to be there on time to save Draco's life when the wards were disabled. The fact that he is one of only a handful of wizards with the ability to disable Hogwarts' wards. The impassioned speech advocating benevolent fascism. The fact that no one knows who he really is and Harry can think of at least three different identities he's taken on. The weird zombie mode that seems to roughly correlate with Bad Things happening. The excessively harsh and sometimes downright abusive way he runs his class. The lack of empathy and inability to accept or even understand love.

My question is, do you think Harry has realized all this and is really strongly suspecting Quirrell for other reasons, and he only told Lucius that the only reason was the curse on the Defense Professor's position? Or do you think Harry is still reluctant to seriously entertain the possibility that it was Quirrell?