why did DD need Snape? /was It's over, Snape is evil

[Tonks]

No: HPFGUIDX 137624

--- In HPforGrownups at yahoogroups.com, "pippin_999" <foxmoth at q...> 
wrote:
> HBP-US ch 23 p 503
> "Had it not been --forgive me the lack of seemly modesty--for my own
> prodigious skill, and for Professor Snape's timely action when I
> returned to Hogwarts, desperately injured, I might not have lived to 
> tell the tale."
> ----
> "Desperately injured" 
> If Snape is evil, if he wanted Dumbledore dead, why didn't he just
> let him die? Who would have been the wiser if he had made a seemingly
> valient attempt to cure Dumbledore and failed? Or slipped him a 
> healing potion that wasn't?


Tonks:

I agree that Snape is still working for DD. But I have aother 
question. DD went to Snape when he was injured and wanted Snape when 
he drank the poison. So is this just because Snape is a better Potions 
Master than Poppy or is there something else that we don't know 
about.  Why is it Snape that DD needs?  Why is it Snape that was able 
to save him?  I wonder if there is more to this that Snape just being 
a good potions master.  Just how good is he?  Better than someone 
whose job it is to be a healer??  There must be some deep secret here. 
What is it?

Tonks_op