Half Blood Prince book

[Zara]

No: HPFGUIDX 165263


> montims:
>For that
> matter, presumably he could have accio'd it at any time if he had 
become
> suspicious of Harry's achievements and seen that the book was 
missing from
> the cupboard.  Couldn't he?

zgirnius:
A slightly different angle on your question - I think Snape was 
suspicious that Harry was up to something he would not approve of 
when Slughorn started raving about Harry's Potions genius, but I 
don't think he knew what. It was only when he found Draco and Harry 
in the bathroom that he suddenly realized what was probably going on.

At that point, he didn't Accio the book to confirm his suspicions, he 
used Legilimency.

Even if he had suspected earlier, it's not Snape's usual style of 
doing business to get the proof and confront Harry with it. Far more 
typical of his approach would be to ask Harry about suspected 
wrongdoing and see what Harry says. The scene in CoS with the 
petrified cat is an example - Snape asks Harry to explain what 
happened. (Harry is concealing the voice he heard - for 
understandable reasons, but Snape can probably tell, and does not 
know why).

The incident of Draco seeing Harry's head in Hogsmeade is another. 
Harry responds by lying (while engaging Snape in a staring contest, a 
detail that, post OotP, always makes me chuckle. We can be sure Snape 
*knew* he was lying.)

And Snape again follows this pattern in the scene we are discussing. 
First he asks Harry where he learned the spell, then, when Harry lies 
to him, he satisfies himself as to the actual facts of the matter.

--zgirnius