Heaping vow upon a vow..

[nkafkafi]

> Carolyn:
>
> Was that the first unbreakable vow that Snape had made? Could it be 
> that the reason that DD had complete faith in the man was, quite 
> simply, because Snape had sworn an unbreakable vow to 
support/protect 
> the Order/Harry..?
> <snip> 
> It would be a neat solution to the thing that's been puzzling us 
from 
> the beginning, because it's clear that making such a vow does 
nothing 
> to improve the temper. It would be so Snape to make his promise, 
> clasp hands with DD, but then continue on detesting the little brat 
> regardless.
> 

Neri:
There's no need for another UV just for that. A Life Debt to James 
would work just as well, and doesn't require any further assumptions. 
The canon is already supplied. For more details see
http://groups.yahoo.com/group/HPforGrownups/message/145024

Now, if you also want Snape to be indebted to Dumbledore, that too 
could be arranged, but would require a few speculations regarding how 
Life Debts work. Nothing really out there, though. The details are in
http://groups.yahoo.com/group/HPforGrownups/message/140493

Neri