Vampires, was Snape, was Class origins

[David]

No: HPFGUIDX 29613

Heather Moore asked:

>  Have we had a solid exposition of vampirism in the Potterverse? 

No.  We have two main clues, I believe.

1) In a footnote in FB, they are classified as beings, and cited as 
one of the reasons centaurs do not want to be so classified.

2) Percy mentions in GOF, as they return home after the World Cup, 
that Rita Skeeter says that the MOM should spend more time stamping 
out vampires, and then says something like "As if it's not 
specifically stated in the Guide to Non-wizarding Part-humans 
that...", when one of his brothers cuts him off, more's the pity.

They are also mentioned in DADA lessons and a few other places.

We don't know if the Guide says they shouldn't be stamped out (so 
Rita is wrong) or that they should (and Rita is wrong because the MOM 
is already being very energetic about it).  I believe the former.

So, are centaurs prejudiced, or are vampires really dark by nature, 
regardless of personal choice?
Is Percy hinting that the real situation is very complicated - what 
is a 'part-human' here? In what sense are they non-wizarding (this 
seems to rule out the very effective wizard Snape)?

I think these mentions suggest that vampires are very much part of 
the backstory - will they come to the front (other than SUAVE members 
being proved correct)?

David