Conspiracies and re-assessments

[Justine]

No: HPFGUIDX 112244

Justine:
We must remember that Snape's existence includes [snip] a pureblood 
superiority mindset, and, most  importantly, an obsession with the 
Dark Arts....  

Magda:
Well, we don't know that really.  
Sirius Black said twice (OOTP and GOF) that Snape was into the 
DarkArts but no one else has....

Chancie:
Acutally if I remember corectly, Sirius isn't the only one who 
claimes that Snape is in to the Dark Arts.

Justine:
And we mustn't forget this:

JL: Prof Snape has always wanted to be the defence against the dark 
arts
teacher. In book 5 he still doesn't get the job Why does Professor
Dumbledore not allow him to be the defence against the dark arts 
teacher?

SF: There

JKR: <sighs> That is an excellent question and the reason is that, I 
have to
be careful what I say here, the reason is that to answer it fully 
would give
and awful lot away about the remaining two books but when Professor
Dumbledore took Professor Snape on to the staff and Professor Snape 
said I'd
like to teach defence against the darks arts please and Professor 
Dumbledore
felt that that might bring out the worst in Professor Snape

<laughs> Somewhat

http://www.quick-quote-quill.org/articles/2003/0626-alberthall-
fry.htm

And while Remus doesn't confirm Snape's predilection for the Dark 
Arts when Sirius mentions it, he certainly doesn't argue the point.

Justine