Harry, Snape and Dementors WAS: Re: CHAPTER Chamber of Secrets Chapter 18:

[pippin_999]

No: HPFGUIDX 189488

Carol:
> 
> I've always assumed that Snape, who is unaffected by the Dementor that Fudge brings into Hogwarts, uses some form of Occlumency to protect himself. Fudge, too, is unharmed by the Dementor, which accepts his authority to the extent that it enters the school with him, ostensibly to protect him, before it pounces on the helpless (but hardly innocent Barty Jr.). How did Fudge keep that renegade Dementor from attacking anyone else? Or did Snape or McGonagall both hit it with their Patronuses (DD not being present)? Or did Snape, who in Percy's words, "knows an awful lot about the Dark Arts"--so much so that DD wants Snape and only Snape to treat his cursed arm after he puts on the ring--use some method that we don't know about to dismiss or destroy the Dementor? We never find out. All we know is that Barty Jr. was its only victim. Personally, I don't think that Fudge or McGonagall did anything except scream at each other and alert Dumbledore--which means that dealing with the Dementor was left to Snape.


Pippin:
I don't think the dementor was a renegade, exactly. Faced with an Azkaban escapee who was zonked on veritaserum and  moreover insane with bliss over Voldemort's return, I think any dementor would have attacked. My impression is that when the dementor in question sensed Barty it swooped ahead of Fudge and Snape, entered the DADA office (whose door had earlier been blown away by Dumbledore) and pounced on the defenseless Barty before anyone could do anything. Even if McGongall can summon a patronus when faced with a dementor (and even Harry can't always manage it), she would have been watching Barty  in case he recovered enough to make a break for it; she wouldn't have been on guard against an attacker from outside. 

I don't think there was any fight with the dementor.   Fudge, no longer having any reason to fear Barty, and wishing to appear in control,  would have dismissed it. And the Dementor, having finished its feast, would have no reason to linger, certainly not in the neighborhood of Albus Dumbledore. 


Pippin