Snape and Harry again.

[pippin_999]

No: HPFGUIDX 114003


> Something else that I find interesting, and it may just be for no 
 reason at all.  Snape taunts Harry with questions that very few 
 students would know.  Why are the Slytherins laughing?  Why 
are they  so sure Snape won't pick on them?  After all, as far as 
we know, they don't know him any better than the Gryffindors 
know McGonagall.<

All the Slytherins aren't laughing, only three of them.

"Draco Malfoy and his friends Crabbe and Goyle sniggered 
behind their hands."

"He tried not to look at Malfoy, Crabbe and Goyle, who were 
shaking with laughter."

The only time there is more general laughter it is (suprise!) at 
Snape's expense or possibly Hermione's.
----
"I don't know," said Harry quietly. "I think Hermione does, though, 
why don't you try her?"

A few people laughed; Harry caught Seamus's eye, and Seamus 
winked. Snape, however, was not pleased.
----

According to JKR's website, the Death Eater children have grown 
up telling each other stories about how Harry might have 
defeated Voldemort. Snape, come to think of it, has surely heard 
these too. Draco's laughter may come from realizing that this 
godlike hero whom he's heard discussed in hushed whispers 
all his life is after all merely human.

I don't think Snape has written off the Slytherins. Draco and his 
gang confine themselves to sneering at Harry and spreading 
gossip about him. Draco, unlike Snape in his youth, is not firing 
curses at Harry every chance he gets, though we saw in GoF that 
he would like to. Somebody is keeping him in line, and since 
besides Dumbledore, nobody has the authority to expel him 
except his head of house, there's only one person it could be.

Pippin