Snape, Lupin, and the map

[Tim Regan]

No: HPFGUIDX 96041

Hi All,

Apologies if this has been done to death in the past – please point 
me to the right thread if you know one.

I've just been listening to PoA again, and I don't get why Snape 
lets Lupin leave his office with the Marauder's Map. If you recall 
Snape is questioning Harry after he sneaked to Hogsmeade under his 
invisibility cloak. Then the map declares itself as more than an old 
piece of parchment to Snape, by each marauder taking it in turns to 
ridicule him. Then 


<quote>
Harry waited for the blow to fall.

    "So..." said Snape softly. "We'll see about this...."

    He strode across to his fire, seized a fistful of glittering
powder from a jar on the fireplace, and threw it into the flames.

    "Lupin!" Snape called into the fire. "I want a word!"
</quote>

Why is Snape summoning Lupin? The reason he gives is

<quote>
"This parchment is plainly full of Dark Magic. This is supposed to 
be your area of expertise, Lupin. Where do you imagine Potter got 
such a thing?"
</quote>

But I got the impression that this was a bluff for Harry, and that 
Snape was aware of the marauders' nicknames. Is this true?

But then Lupin bluffs Snape that it's indeed from Zonko's, to which 
Snape retorts

<quote>
"You think a joke shop could supply him with such a thing? You don't 
think it more likely that he got it directly from the manufacturers?"
</quote>

Again it feels like Snape knows who Moony is. But then comes the 
weird bit

<quote>
"Well!" said Lupin, clapping his hands together and looking around 
cheerfully. "That seems to clear that up! Severus, I'll take this 
back, shall I?" He folded the map and tucked it inside his 
robes. "Harry, Ron, come with me, I need a word about my vampire 
essay -- excuse us, Severus --"
</quote>

Now, why doesn't Snape reply "No Lupin, I think I'll investigate the 
parchment further"? The marauders were good, but it's difficult to 
imagine teenage magic defeating our Snapey for long. When I read it 
first (and second, and third, 
) I'd assumed that Lupin's remark " I 
need a word about my vampire essay" was designed to stop Snape 
taking it further. But we now know (from the web chat)

<quote>
Megan: Is there a link between Snape and vampires? 
JK Rowling replies -> Erm... I don't think so.
</quote>

So what does Lupin have over Snape in this altercation? Why doesn't 
Snape keep the map?

Cheers,

Dumbledad.