Legilimens and Occlumens (was Snape's Fury)

[davewitley]

No: HPFGUIDX 85773

Eloise wrote:

> After OoP, however, I am left wondering a few things.
> If Snape and Dumbledore are such experts at occulomency, I wonder 
how between 
> them they were not able to divine who was the spy in the Order of 
the 
> Phoenix. OK, I let Snape off this one, as I assume he was working 
deep under cover 
> and the members of the OoP didn't know about him. But Dumbledore?
> 
> But how come Snape didn't suss Crouch!Moody? Was he really so 
intimidated by 
> Moody's apparent suspicion of him that he was unable to divine his 
true 
> nature?  

Interesting questions, which point up how little we know of the 
Legilimens and Occlumens spells, since Snape never got very far in 
his lessons with Harry.

We only have a general idea of what Legilimens can accomplish, for a 
start, when not resisted by its object.  For example, the memories 
shown seem to be random, perhaps biased slightly in favour of 
unpleasant memories.  Scenes from Pettigrew's childhood would not 
tell Snape or Dumbledore a great deal.  They would have to light on 
scenes directly involving the Death Eaters.

Legilimency does appear to confer an ability to tell if someone is 
lying, though how this works isn't clear.  We know Occlumency can 
counter this, since Voldemort apparently didn't rumble Snape.

The next question is whether the use of Occlumency can be detected 
by the Legilimens.  In the hands of the novice Occlumens, yes, 
clearly, because we know Snape could tell when Harry was blocking.  
However, we know that Snape could spy on Voldemort undetected, which 
implies that his Occlumency was so advanced that, not only could he 
prevent Voldemort perceiving the truth, but presumably also provide 
a stream of suitable memories to make Voldemort think his 
Legilimency was succeeding.  Whether this was done by controlling 
the flow of true memories to build up a partial picture, or 
providing false ones as well, we don't know.

In the case of Crouch, disguised as Moody, all that would be 
necessary would be to block all attempts at Legilimency, as that 
could be explained by Moody's notorious suspicion.  It would, IMO, 
seem entirely natural to Snape and Dumbledore that Moody would 
refuse to let anyone inside his mind.

We also don't know the extent to which successful Occlumency opens 
up the mind of the Legilimens.  Harry managed it with Snape, but 
that was using the Protego spell, which clearly gives the game 
away.  would there have been a risk, supposing Snape tried to read 
Moody's mind, or Dumbledore Pettigrew's, of the tables being turned 
and sensitive information flowing the other way?

Then there is the final issue: under what conditions would 
Dumbledore and Snape (and the wizarding world generally) consider 
the use of Legilimency acceptable?  In training, clearly, but then 
Dumbledore AFAWK sanctioned the use of Ungorgivable curses for 
this.  But against a supposed ally?  One might suppose that, at the 
time of recruitment it would be done.  But afterwards?  Suppose 
Pettigrew genuinely joined the order and was only later 'turned' by 
Voldemort - what degree of suspicion would order members feel 
justified this form of invasion of privacy?  Again, we just don't 
know.

David