Snape - what about the unbreakable vow?

[Matt]

No: HPFGUIDX 133934

--- In HPforGrownups at yahoogroups.com, "davenclaw" <daveshardell at y...>
wrote:
> [M]y big problem is the Unbreakable Vow.  For this to have 
> all been a plan, DD must have told Snape that if he needed 
> to kill him in order to stay close to Voldemort, then he 
> should do so....  But the problem I have with this is that DD 
> couldn't have known that he would be so weakened and close to 
> death at the time that Draco confronted him.  So it was 
> possible, due to the vow, that Snape might have had to kill 
> a perfectly healthy and powerful Dumbledore. 

Really the most you can say in your hypothetical is that Snape might
have had to *try* to kill a perfectly healthy and powerful Dumbledore.
 I think we can all agree that Snape would not have succeeded in such
an attempt.  Indeed, a perfectly healthy and powerful Dumbledore
likely would have the wherewithal to avert any confrontation in which
Snape would even have been put to the choice.  

In similar vein to the self-fulfilling nature of the Prophecy, the
hypothetical bargain between Snape and Dumbledore would only come into
operation at such a time as Malfoy was actually able to corner a
weakened Dumbledore, i.e., the situation in which it the bargain was
worth making.

-- Matt