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

[Lisa]

No: HPFGUIDX 172028

--- In HPforGrownups at yahoogroups.com, "k12listmomma" 

<snip>
I think it simply means to "manipulate the 
> circumstances to appear as if the snake is "approaching" Dudley", so 
that 
> Dudley would be scared out of his pants. 
=======================

Lisa:

That's just it -- "manipulating the circumstances" implies intent, and 
there was none on Harry's part, as I said, malicious or otherwise.  It 
just happened -- much like the regrowth of the hair.  Harry didn't 
control the snake at all -- he simply watched the events.  And yes, 
that is canon, because we saw the actual event unfold.  How Harry views 
it in hindsight is irrelevant -- I'm sure we've all done things in the 
past that we could look back on and describe differently.