Two Plot Problems

[potioncat]

No: HPFGUIDX 187648


> 
> Carol responds:
> I agree that Snape's response was surprisingly fast and that it's quite a coincidence that he (the inventor of the spell and probably the only person who knows the countercurse) was on hand to cure it.
snip
 
> Sorry to ramble. I agree with Geoff that keeping an eye on Draco because of the Unbreakable Vow (and possibly keeping an eye on Harry, too, for other reasons) is not sufficient explanation for his highly convenient appearance. The Vow itself may have had some sort of magical power; after all, if Draco had died, Snape would have died, too, for breaking the vow.


Potioncat:
It was pretty darn quick. I don't see it as a coincidence so much, since we knew Snape was looking out for both boys; and the whole point is that Harry learned the spell from Snape's book.

Yet Snape has a history of being around when Harry least suspects--lurking in dark corners and such. He could have been patroling around the area he knew Draco to visit. 

We know that there is a level of communication between Dark Marks. Perhaps his Dark Mark alerted Snape that Draco was in some sort of danger when Draco and Harry first started dueling. 

So, while it was a rapid response, I don't find it a plot hole, or a big stretch to think he would be there.