Rowling interview transcript

[pippin_999]

No: HPFGUIDX 180353

> > Carol, wondering what JKR thinks would have placed little Severus in
> > Slytherin besides his own delusion that it was the House for "brains"
> > but not at all sure that I want to hear the answer

Pippin:
He had a strong preference for Slytherin, and as we know, the Hat takes your
preference into account. If the Hat had known how brave Severus would become,
it might have argued, or argued harder, for Gryffindor, IMO. But the Hat has no talent
for divination that we know of. 

Irene:
> She didn't put a lot of thought into his motivations, I'm afraid. Again, 
> I know it's only interview, but she'd said something completely 
> ridiculous in response to why he'd joined DE - something like he thought 
> if he becomes a really powerful wizard, it would impress Lily. Duh.

Pippin:
Why is that ridiculous? Is it unusual for someone from an abusive, violent
background to think that only powerful people are loved?  I don't think
Snape understood till Dumbledore made that remark about being sorted too
soon that Lily could have loved him for his courage. *That's* why he looked
stricken in my reading, not because he was agreeing that Gryffindor would
have been a better fit. 

And Lily did have a touch of the bad boy thing going -- she was being
attracted to Bully!James despite herself. 

Of course if Snape had known that he was going to get caught up in pureblood
mania and insult his dearest friend, let alone get involved in a plot to murder her,
he'd have wanted to be in a different house, IMO, although as we know there
were DE's from other houses, Pettigrew for sure.  But nobody knew that was 
going to happen either.  Nobody, except a few visionaries like Dumbledore,
understood at first that Voldemort meant to take pureblood mania so far. 

Pippin