Nagini: If she's not a Horcrux, what the heck is she?

[mandorino222]

No: HPFGUIDX 171998

Carol said:

Anyway, I doubt very much that the friendly (male?) boa constrictor
from SS/PS is the same as Nagini, whose personality (so to speak) is
as venomous as her bite.

Nick then:

I certainly agree that the personality traits exhibited by the two 
snakes are different enough to cast doubt on the "same snake" theory, 
but LV could have affected those changes himself.  For all we know, 
Nagini could be under the snake verson of the Imperius curse, and the 
highly poisonous fangs could be a LV physiological amdendment (akin to 
Wormtail's hand).

Nick (who will continue to cling to his theory until conclusive canon 
is produced)