What did Snape know, and When did he know it?

[houyhnhnm102]

No: HPFGUIDX 169344

Mike:

> The problem I have with all this *evidence* is that 
> it doesn't seem to be enlightening Severus Snape to 
> anything. Oh sure, the Marauder's Map is something 
> new and Snape cleverly deduces its true purpose. But 
> he catches Harry with it. And since he recognizes 
> Black as one of the "manufacturers", shouldn't that 
> point to Black *not* needing any *inside help* to 
> get into the castle?

houyhnhnm:

Except that Snape doesn't know the history of the Map, 
its confiscation by Filch and abstraction by the Weasley 
twins who then gave it to Harry.  He has to account for 
the Map's falling into Harry's hands. "You don't think 
it more likely that he got it /directly from the
manufacturers/?"  Since Harry obviously didn't acquire 
the Map from Sirius, that leaves Lupin.   Which would not 
necessarily show that Lupin was helping Sirius get into 
the castle, but it would certainly suggest that Lupin was 
in cahoots with Sirius in an attempt to lure Harry out.

Mike:

> Again, Snape was still a DE, even if he had changed 
> his allegiance by then. So why does he persist in this 
> belief that Black was the one who sold out the Potters? 
> Again, I'm not saying he would or should come forward 
> with this information. But in the Shack, my impression 
> is that he is suppose to be unaware of Black's true 
> status. Snape still blames Black for selling out the 
> Potters. Is that a charactor flaw of Snape's to believe 
> irrational things about Sirius?

houyhnhnm:

My point was that I was trying to refute the assumption 
that Snape's loyalty turns on whether or not he knew that 
Peter Pettigrew was Wormtail the traitor.  The DEs in the 
know, at least according to Sirius--if we can rely on his 
testimony, *knew* that Peter Pettigrew was the traitor.  
The question of Snape's loyalty to Dumbledore turns on 
whether he was in the know about *Peter Pettigrew*, 
whose alias, it seems to me, is irrelevant to the discussion.

If Snape *knew* all along that Peter was the Order's 
traitor and witheld that knowledge from Dumbledore, 
then he is not persisting in a belief that Sirius was 
guilty because of a character flaw; he is out-and-out 
dissembling and he is not Dumbledore's man.

The thing is, we don't really know what Snape's status 
was among the Death Eaters during VWI.  We don't know 
what DE activities he participated in. All we know is 
that Voldemort sent Snape to apply for a position at 
Hogwarts to spy on Dumbledore at the time the prophecy 
was made and that he failed to do so.  We have evidence 
from both Fudge and Sirius (though I can't remember 
where now) that Peter was betraying the Order for around 
a year before the Potters' deaths and this was the same 
time period during which Snape was spying for Dumbledore.

Given what we have seen of the way Voldemort operates, I 
think it is entirely plausible that Snape was not able to 
learn the identity of the traitor.  And given the fact 
that I believe there is abundant against both ESE!Snape 
and OFH!Snape, the only possible conclusion for me is that 
Snape did not know Peter was the traitor.

BTW, an addtional nugget gleaned from the Shrieking Shack 
scene: Snape's fanatical gleam at the thought of proving 
Dumbledore wrong about Lupin.  Why would an evil Snape be 
gleeful at the thought of proving Dumbledore could be 
mistaken in his trust of someone if he's been doing it 
successfully for fourteen years?  It seems to me that 
whatever his hatred for Lupin, he would be anxious to 
promote the belief in DD's infallibility since that is 
what his position in the respectable WW rest on. 

Mike:

> Or is this a plot hole that we aren't suppose to explore 
> too closely?

houyhnhnm:

Very possibly.  We'll know in 50 days + the amount of time 
it takes to read and deconstruct.