Snape and Crouch Jr. (Was: Trelawney, Polyjuice Potion, house elves and Fudge

[justcarol67]

No: HPFGUIDX 113574

sad1199 asked:
<huge snip> does Snape 
> have some idea that Moody is Barty Jr.? He knew something was amiss 
> with Quirrell. <another huge snip>

Carol responds:
I think Barty Jr. is very lucky in that his victim, Alastor Moody, has
grounds for hating, or at least thoroughly disliking, both Karkaroff
and Snape, and knows about their background as former DEs (or in
Karkaroff's case, a traitor and turncoat who actively betrayed other
DEs). So Crouch Jr. finds it quite easy to play the role of Moody and
make Snape both angry and uneasy without arousing suspicion regarding
his true identity. Also Snape has reason to suspect *Harry* of
breaking into his office to steal potion ingredients, so he doesn't
put the pieces together with quite his usual astuteness. Still, I
think Snape must have reported the midnight encounter with "Moody" to
Dumbledore, including the burning sensation in his arm, as somehow
suspicious, and I think that incident combined with several others
(Imperioing and transfiguring his own students, showing up a bit too
quickly when Crouch Sr. was acting strangely, and quite possibly
visibly stunning Fleur de la Couer at the Tri-Wizard Tournament)
helped Dumbledore (not Snape) to figure out who "Moody" was and how he
transformed himself. But I think that Snape himself, though suspicious
and resentful of "Moody," was too uncomfortable around that roving eye
to spend much time in "Moody's" company and his own suspicions of
Harry kept him from suspecting that "Moody" might be an imposter out
to endanger Harry. Certainly his astonishment on seeing "Barty
Crouch!" lying prone in Moody's office is genuine. In fact, his
reaction and McGonagall's are so similar that it's almost comical.

So, as intelligent and shrewd as Snape is (he knew perfectly well who
was standing on top of the stairs in his invisibility cloak, for
example), Crouch's choice of people to impersonate (or his luck in the
victim chosen for him) combined with Snape's belief that Harry put his
own name in the cup prevented Snape, IMO, from figuring out that Moody
was an imposter with a sinister ulterior motive. And of course it
would have been most unlikely for Snape to suspect Crouch Jr., whom he
thought had been dead for thirteen years. However, Dumbledore, using
the Pensieve, had been examining memories and their relationships in
various contexts throughout the year. The incident with Winky and the
Dark Mark, and Mr. Crouch's odd behavior and apparent illness probably
led to his studying a number of Crouch-related memories, including the
one involving Barty Jr., and he must have thought about them again
after the madness and disapearance of Mr. Crouch. His conclusion that
"Moody" was Barty Jr. was not based simply on Moody's taking Harry to
his office against orders. It was based on a year-long examination of
odd events, making connections between seemingly unrelated thoughts
using the Pensieve. (See previous paragraph.) Snape did not have that
advantage.

Anyway, that's my interpretation, which is not so much an answer to
"why didn't Snape know?" as to "how in the world did Dumbledore
know?", the big question that came to my mind when I first read GoF.

Carol, with apologies for the somewhat jumbled thoughts, but I don't
have a Pensieve, either