"revulsion and hatred etched in the harsh lines of his face"

[Deb]

No: HPFGUIDX 135647

(Snip) 
Leslie wrote:
That is *not* how the text reads.  And there will be no "real" 
explanation until book 7.  I believe Snape did not want to kill 
Dumbledore, dreaded doing it, and regretted doing it.  But did it 
because it had to be done.  The circumstances of that have yet to 
be revealed.  The mere fact that Rowling leaves Snape's motivations 
and his feelings suspect is cause enough for doubt.

And ask yourself this...if you "had" to kill something you 
loved...a beloved dog lying half-dead in the road, injured beyond recovery by a passing car, what look, as you pulled the trigger, would be on *your* face?  

Horror.  Revulsion.  Maybe even something that looked like hate.  

But that doesn't mean you want to kill your dog.     


Deb writes:
I agree Leslie - and what if this is what preceded this necessity? 

I think that DD is telling him, as he has on other
occasions to "Please get on with it, do what I told you to do".
And I think the necessity for this is related to the cave, the lake, 
the liquid DD drinks... and to what DD strongly believes is worse than death. My strong suspicion is  DD thinks that a living death... like a Inferi, zombie, or some other entity that is dead but kept animated to do the bidding of a Dark Lord..... would be much worse than death! There has been some speculation about what was in that bowl ... what if it was the potion, or first part of a spell, that creates Inferi... "corpses ... dead bodies that have been bewitched to do a Dark Lords bidding."... as DD tells Harry on their trip to
Slughorn's house.

What if the liquid in the stone bowl is the Draught of Living 
Death... mentioned several times in previous books. DD tells Harry it won't immediately kill him, and says, once back at Hogwarts, that he has come back "after a fashion". Or if not the potion in the bowl then the water in the lake... DD tells Harry 3 times not to touch the
water.... perhaps his warning is more than just not wanting to "wake
up" what dwells beneath the surface of that vast lake. For it seems
to me that under this lake dwells LV's army.... an army of Inferi.
The corpses of most of the people he (and maybe the DEs) have
murdered or caused to disappear during his reign of terror. Harry 
just splashes the water from the lake onto DD's face .... and
perhaps DD hopes that that will not activate the Inferi curse...

So Harry gets DD back to Hogsmead and DD wants Snape right away for
his superior knowledge of the Dark Arts.... and Potions. I suspect
he is hoping, or knows, that Snape has an antidote to whatever it
was that he drank... or is carrying a bezaor(though Snape said in
the very first Potions class that bezaors will protect one
from "most poisons"... so maybe it won't work on all poisons). But I
also suspect that there is a time component... that the antidote
must be given quickly... and he does not get to Snape fast
enough ... so when he is lying there on the tower, and Snape comes
through the door, the only thing left to save DD from becoming one
of LV's Inferi is for Snape to kill him.

And Snape, having promised to save DD from this terrible fate, is
angry beyond measure that this has come to pass, disgusted and 
revolted by the possibility of his mentor becoming one of LV's 
Inferi ... and resolute in his determination to save DD from a fate worse than death.

Deb