question about crookshanks

[Carol]

No: HPFGUIDX 185772

bonsaikathy wrote:
> >
> > I know this is off the regular topic being discussed at present
but I have a question. In POA what is the relationship between
Crookshanks and Sirius Black in his dog form? <snip>
> 
Montavilla47 responded:
> 
> Crookshanks was aiding Sirius--although there's no particular reason
why he should.  Crookshanks starts harassing Scabbers from the moment
they meet--at the pet shop where Ron is getting advice.
> 
> So, perhaps it was a mutual antipathy towards Scabbers that
Crookshanks and Padfoot bond over.  
> 
> In addition to chasing Scabbers, Crookshanks aids Sirius by bringing
him the list of passwords, and by delivering the order for the
Firebolt broomstick.
> 
> My interpretation of the role Crookshanks plays is that he's 
helping Sirius because he senses Scabbers's guilt and Sirius's good
intentions.  <snip>

Carol responds:
Sirius Black also tells Harry that Crookshanks is "the most
intelligent of his kind" that he's encountered. Since, as Montavilla
points out, Sirius must be communicating with him in some complex way.
I thought at first that he would do so as Padfoot, but it appears that
Crookshanks (like Filch's cat, Mrs. Norris, and Mrs. Figg's cats)
understands human language.

I suspect that Crookshanks immediately sensed something wrong with
Scabbers, either that he was an Animagus or that he was evil or both.
It certainly wasn't just the normal "cats eat rats" reaction since the
rope-skipping black rats don't produce the same reaction. Quite
possibly, Crookshanks had a similar initial reaction to Padfoot, but
once Sirius, in human form, started talking to him and befriending
him, explaining who and what Scabbers was (a bad Animagus or a Dark
Wizard Animagus), Crookshanks was probably happy to work for him,
especially since he'd already sensed that Scabbers was bad. (We see
the same thing with the Sneakoscope that goes off in Scabbers'
presence--though, of course, Ron always attributes its behavior to the
wrong cause.)

Carol, as always unsure of just how much of this backstory JKR worked
out for herself