Snape as "half dead"

[ritadear2]

No: HPFGUIDX 37211

This isn't in response to any particular post, but to the theories 
that someone can be "half vampire" or "half dementor".  From my 
understanding, vampires and dementors are not living things.  
Vampires are dead, no?  How could one be partially dead?  
Could a dead thing mate and cause life within another to make a 
half dead child?  I don't see how this is possible.  Same with the 
dementor concept.

If someone could explain this, please do!

Rita