Harry begins to act like someone I know...

[potioncat]

No: HPFGUIDX 99070

Potioncat snipping part of my post:
 I also  think he originally went after the trio because he thought 
they would be in danger from Lupin. 
> >


Meri wrote: 
> I don't think Snape would have been able to see the trio on the 
map. 
> The Marauder's Map doesn't show the Shreiking Shack, after all. He 
> may have thought perhaps that Lupin would be a danger to someone, 
> but I think that by this time he suspected that Lupin and Sirius 
> were in cahoots as it were, judging by the fact that he didn't 
seem 
> at all surprised that Sirius was there in the shack. I think that 
> concern for HRH's lives was the last thing on his mind that night. 
> He was much more interested in settling old scores with Black and 
> Lupin. 


Potioncat again:
Let's see who can get to canon first.  It may be awhile before I 
can.  I don't remember what Snape saw on the map.  But, if  he 
didn't see the trio, he didn't see Lupin or Black either.

As far as old scores go.  I have to admit, Snape is the type for 
revenge.  But think of this:  He advised DD not to hire Lupin in the 
first place, because he felt Lupin might be helping Black, 
particularly when Black did get into Hogwarts. Now, in the Shreiking 
Shack what does he find, but the good old buddies, Lupin and 
Black....just as he suspected. Every bad thought he ever had about 
Black appears to be well founded and true....at least to him.  

So he has a werewolf about to transform, a murderer, an injured 
student and two students who think Black and Lupin are nice guys....
Come to think of it, it's no wonder he goes to pieces later in the 
evening!!!!
Potioncat