Troll Question

[houyhnhnm102]

No: HPFGUIDX 154466

Laura:
 
> Since this is about Book 1, it has probably been discussed
> before, but I have a question about the troll.  If Quirrell's
> contribution to guarding the Stone was to bring in the troll,
> then Dumbledore at least would have been aware of that.
> Knowing that Quirrell had done so, how could he have not
> informed Snape and the rest of the teachers that Quirrell
> probably let the troll in at Halloween?  How could Quirrell
> act so afraid of the troll in front of McGonagall and Snape
> in the dining hall and in the bathroom scene?  Wouldn't
> that automatically compromise his believability?

houyhnhnm:

This has bothered me, too.  It is possible that each teacher came up a 
protection but did not actually put it in place. So Professor Sprout 
provided the Devil's Snare from her greenhouses, Professor McGonagall 
transfigured the chess pieces, etc., but Dumbledore actually assembled 
everything.  In that case each teacher knew of his or her own 
protection and knew that there were multiple enchantments guarding the 
Stone, but did not know the exact nature of the others' protections, 
thus they need not have known about the troll guarding the Stone.

But Dumbldore would have to have known.  Did he send Snape to the 
third floor or was Snape acting on his own?  Why did Dumbledore send 
Hagrid to retrieve the Stone from the second most secure place in the 
WW the day before it was stolen?