New(?) questions about the Unbreakable Vow

[zgirnius]

No: HPFGUIDX 141853

zgirnius:
I'm going to rearrange a bit, since a lot of what I say is in answer 
to your final question...

SSSusan:
> Alright, so a goodly portion of this is definitely not new ground.  
> But does anyone have an answer for the question of WHY Snape paused 
> and then reintroduced a topic he could've let drop?
> 

zgirnius:
I'm glad you asked, because I definitely have an opinion ;-)

My theory is that Snape did not know the task. And he was at the 
time, acting as Dumbledore's spy among hte Death Eaters, so when he 
heard about a top-secret important plan of hte Dark Loed,he naturally 
wanted to hear more. 

Then why cut Narcissa off, you ask? Well, the subject actually came 
up once before the quotes you supply. Right after Snape, Narcissa, 
and Bellatrix drink their toast to the Dark Lord. (P. 25, US edition):

"You were saying, Narcissa?"
She took a great shuddering breath and started again.
"Severus, I know I ougth not to be here, I have been told to say 
nothing to anyone, but-"
"Then you ought to hold your tongue!" snarled 
Bellatrix. "Particularly in present company!"

There follows a long digression into how Bella's appraisal of Snape 
is incorrect, as Snape attempts to explain his numerous past actions 
to Bellatrix as being simply what any other loyal DE in his position 
would have done. As Snape himself points out, this is necessary for 
Snape's purpose (learning what it is exactly Narcissa is supposed to 
tell noone about), since until Bellatrix is satisfied, she will not 
let Narcissa get to the point. 

"Narcissa, I think we ought to hear what Bellatrix is bursting to 
say; it will save tedious interruptions."

Many pages of explanations ensue, at the end of which, Snape *still* 
has not succeeded. We learn, top of p. 32, that

"Bellatrix still looked unhappy, though she appeared unsure how best 
to attack Snape next."

I think Snape believes that any attempt by Narcissa to drop any juicy 
details of the mysterious thing she is not to discuss with anyone 
would again result in 'tedious interruptions' by Bella. But in the 
discussion with her, he has confirmed that she is currently in 
disfavor to some extabt, so he decides to bluff. He interrupts 
Narcissa to preempt Bella (and in fact Bella seems pleased for the 
first time when he does so). He then makes a show of ensuring they 
are not being watched (again, at least in part for Bella's benefit) 
before 'revealing' that he already knows the plan.

> SSSusan again:
> *Was it the DADA jinx in operation and he couldn't help himself?  

zgirnius:
My opinion would be that it may have been affecting his judgement. He 
thought he saw a clever way out of it, or somethign to that effect.

> SSSusan again:
> *Was the UV a total surprise?  Or did Snape hope to be able to show 
> his loyalty because he knew Narcissa would ask him to help Draco?  
> Was that his goal but the 3rd vow was a surprise?  

zgirnius:
Yes, I suspect the UV was a surprise. However, based on Narcissa's 
previous comments, misjudged the scope of the Vow. He was expecting 
to be asked to protect Draco.

> SSSusan again: 
> *Was it part of a plan to do whatever necessary to convince Bella 
> of his loyalty to Voldy?  

zgirnius:
IMO, only in so far as this was necessary to gain her and/or 
Narcissa's trust to learn more about the plan.

> SSSusan again: 
> *Was it because he's ESE! and he wanted to be in on killing DD?  

zgirnius:
Seems to me that he could be in on that without taking any Vows...but 
I suppose the DADA curse could mess with the logic of an ESE Snape 
too. (It does not appear to have done Crouch Jr. any favors...)

I accidentally snipped the reference to ACID POPS...this could 
certainly be a reason to agree to the UV. But I think that the 
overall reason for the conversation was motivated by 'secret agent' 
reasons. Which, without that pesky third clause, could be quite 
compatible with a desire to help out Narcissa and/or Draco.