Pondering a Snape thing

[Amanda Lewanski]

No: HPFGUIDX 3119

Something's been bothering me. Is it quite clear that when Snape gets
insulted by the Marauder's Map in book 3, that he knows who Padfoot,
Moony, Wormtail, and Prongs were? On the one hand, if he did, he seems
to have let the map incident go amazingly lightly, and to have taken a
rather weak explanation from Lupin.

The reason I ask:

Snape was out cold during all the action in the Shrieking Shack when
Peter Pettigrew was revealed. Up to the end of book 3, Snape honestly
didn't know Peter Pettigrew was still alive, so while extreme, his
actions toward Sirius were nonetheless appropriate given his character
and the knowledge he possessed at the time. The excuse that he gives
Fudge for the behavior of Harry, Hermione, and Ron I put down to an
unusual generosity, stemming from his impending recognition, whether he
believes it or not. But he doesn't know Pettigrew is alive or that
Sirius' tale is true.

I wonder if Dumbledore has clarified things for him off-camera, so to
speak. Pettigrew is never called anything but Wormtail, and the first
mention of Wormtail in front of Snape in book 4 is when Barty Jr. says
his master showed up at his door in his servant Wormtail's arms. No
mention is made of Snape's reaction to this, which makes me wonder.

If Snape knows Wormtail is Pettigrew, this is the first we know that
Snape must realize that Sirius was innocent and that he was in the wrong
in the book 3 action. This explains to me why, when Sirius reveals
himself at the end of book 4, Snape doesn't go running for the
authorities or make any accusations. He hates the man, yes, and showe
it, but he does *not* react like someone faced with an evil Voldemort
supporter.

However, if Snape has *not* connected Wormtail with Pettigrew, why would
he agree to work with Sirius Black, who he must still believe was a
traitorous supporter of Voldmort, responsible for many deaths?

Any thoughts?

--Amanda