Snape on the tower (Was: Cohesion)

[pippin_999]

No: HPFGUIDX 162329

Neri:
All this he does
> *before* he knows of Dumbledore's grave situation. He doesn't even
> know for sure  that Dumbledore is in the castle at all. 
>snip>
. Draco is obviously making his final attempt at Dumbledor's life and 
if he fails and/or get hurt, Snape is dead.

Pippin:
And how would Snape know that Draco is on the tower? 

He knows that Death Eaters have succeeded in invading the
castle and that some of them must be on the tower, but whether Draco
is there or not he cannot know. For all Snape knows, Draco is dead
already -- he is only vowed to protect Draco to the best of his
ability, so if Draco has died despite Snape's best efforts, Snape is
off the hook for protecting Draco, and maybe for carrying out
the task as well, since it can no longer prove necessary in order to
save Draco.

But if Snape doesn't know where Draco is, his
best effort requires him to find out, and that means he doesn't
have time to wait for reinforcements to arrive, nor can he linger
to help the contingent fighting at the base of the tower. 

Obviously whether Snape followed it or not there was a plan, or
 Dumbledore's 'Severus please' was just a craven plea for mercy, 
which is ridiculous, IMO.

Pippin