The mystery of the DADA “curse” (Long)

[catjaneway]

No: HPFGUIDX 134426

The whole question of the "cursed" or otherwise magically time-
limited DADA position really has my brain spinning. It seems to me 
that there are several questions that are linked together in this 
one mystery, and if unraveled it could provide some interesting 
answers to other seemingly unrelated questions. So here are some of 
the interlinked questions that I see and some possible answers: 

(I apologize for the lack of supporting quotes, my husband has my 
copy of HBP!)

1. Why did Tom Riddle want the DADA position? And why did he curse 
it when he didn't get it?  What was the curse? 

Dumbledore speculates that Riddle may have wanted to find something 
from Gryffindor or Ravenclaw at Hogwarts, but never got the chance. 
The curse would most likely be something that would assist him in 
achieving that goal. Limiting DADA profs tenure to one year would 
help by making the position always open for LV or his surrogates, 
but it doesn't completely explain the havoc that DADA profs are able 
to wreck through the years, and also doesn't explain why Snape was 
so keen to have the job (see below).

2. Why did DD finally give the position to Snape this year? For 
years he had thought that having this position would cause Snape 
to "relapse." We know that DD had figured out that there was some 
kind of curse on the position, at the least limiting it to one year, 
possibly doing more. What was different this year to make DD change 
his mind and take the risk? 

One simple explanation is that he needed to bring Slughorn on to the 
staff in order to get the Horcrux information (as well as to protect 
Sluggy), and since HS is a potions prof, Snape had to be displaced 
to DADA. 

3. Why did Snape keep applying for the DADA position? He was 
perfectly able to spy on DD and the Order as a Potions prof. 
Furthermore, in "Spinners End" when Bella accuses Snape of not 
taking advantage of his position at HWs to do some damage to the 
enemy, he first defends himself by saying that he never got the DADA 
position. Bella basically says "so what?" and Snape changes tacks. 
But it seems significant that Snape seems to think that DADA was 
necessary for him to accomplish whatever it is that LV wanted done 
at HWs. This brings me back to -- "what was the nature of the 
curse???"

4. Why were all those DADA profs able to make so much trouble right 
under DD's nose? Quirrel has LV right in the back of his head, and 
is nearly able to steal the Philosopher's Stone. Barty Crouch Jr. is 
able to fake being Moody all year, enter Harry in the Tri-Wizard 
Tournament, help him win, and still nearly kill him after he escapes 
LV. Umbridge is able torture Harry and take over the school. Lupin 
and Lockheart aren't really sources of trouble, but they are able to 
keep secrets from DD. Finally, Snape is able to catch DD at his 
weakest moment and kill him. DD, who seems to have minute knowledge 
of everything that concerns Harry, doesn't notice these things?

Could it be that the curse is a kind of anti-Legilimency or Secrecy 
Cloak type thing that prevents DD from noticing what the DADA 
teacher is up to?  This would make sense from LV's point of view – 
it would allow him to plant someone in that position who could then 
go find the Ravenclaw or Gryffindor artifact without getting 
caught.  This would also help explain why Snape couldn't leave HWs 
until he had obtained the DADA post. If his original mission was not 
only to spy on DD, but also to steal an artifact, he might 
reasonably need to be the DADA teacher to do it. In fact, I'll bet 
anything that LV wants Godric Gryffindor's sword, whether or not he 
still thinks he needs to make another horcrux. (And since Snape 
apparently failed to get the sword before leaving HWs this year, due 
to having to kill DD and get out of town, LV may not be quite as 
happy with him as one might expect.)  Finally, this would also 
explain why DD was so uncharacteristically "blind" when it came to 
Snape. It wasn't exclusively due to his so-called "flaw" of always 
seeing the best in people, it was also due to some kind of magical 
confundment cast on the DADA position by LV. 

Whew, glad to have all that off my chest! If you made it to the end, 
I'd love to hear your "yeah, buts
"!

Janeway