First lesson WAS: Re: Marietta, was Slytherin's Reputation

[Carol]

No: HPFGUIDX 185916

Carol earlier:
> > That the barrier created by Protego does more than block the
"minor to moderate hexes and jinxes" mentioned by the Twins in
connection with their Shield Cloaks and Shield Hats (HBP Am. ed. 119)
is shown when Harry casts a Protego to protect Ron from Hermione in DH: 
<snip quote>
> > If neither Hermione nor Ron can get through the conjured wall 
between them, a conjured snake could not get through the conjured wall
around Harry that would have been created had Lockhart told him how to
cast a Protego.
> 
> 
> Annemehr:
> I completely forgot about that bit in DH.  Interesting.
> 
> So, I wonder if Snape could have used it to shield himself from 
Buckbeak at the end of HBP - or, can't you use it when you are 
moving, because then you'd just run into your own wall? <snip>

Carol responds:
I don't think you'd run into your own wall because you'd be running
away from the pursuing hippogriff. I think the main reason that snape
didn't use it was that he was keeping an eye on the gate, which was
close at hand. I'm trying to remember--did Harry use Protego against
any of the creatures in the TWT maze?
> 
> > Carol, wondering what Annemehr thinks that Snape was "up to" given
> that we know he was protecting Harry
> >
Annemehr:
<snip>
> 
> If he was only trying to humiliate Harry, or to deflate his ego a
bit (after that flying-car incident, you know), then any jinx would
have sufficed, since Harry didn't know Protego.
> 
> The only thing that makes sense is that he was trying a little
experiment to see whether he could evoke Parseltongue in Harry (in 
connection with Dumbledore's plan). Because, DD knew *who* was 
opening the Chamber; it was Tom Riddle all the time.  And Harry was
someone with a connection to Riddle.

Carol responds:
I see! So we're back to the suggestion I made earlier in this thread:

Carol earlier:
> > I'm not sure about the Serpensortia spell, but it *may* have been
Snape's way of testing to see whether Harry was a Parselmouth. It
certainly served that purpose whether it was his intention or not.
And Snape easily Vanished the snake before it could do any harm.

Carol again:
I abandoned that particular point because I couldn't think of any way
to support it. The Serpensortia looked to me primarily like a plot
device to allow Harry to speak Parseltongue and set up the suspicions
of him as the Heir of Slytherin, especially after the next Petrified
student just happens to be Justin Finch-Fletchley. Certainly, it's
clear from the beginning that Snape intends to Vanish the snake with
no harm to Harry. And, as you say, any old hex would do if he were
just trying to humiliate Harry. Why not cause him to sprout rabbit
ears or something? But the only piece of solid evidence I can find is
Snape'e expression after Harry starts speaking Parseltongue. Instead
of looking surprised or horrified, he looks "shrewd and calculating"
(CoS Am. ed. 193). He certainly could not have anticipated that
Lockhart would try to Vanish the snake, causing it to move angrily
toward a student. I wonder what he *did* expect--and whether he teally
thought that Harry might have been responsible for the attacks.

At any rate, whatever that scene was about, it wasn't humiliating
Harry. And, as others have pointed out, Snape isn't officially in
charge even though he steps in to pair off Harry and Draco rather than
Neville and Seamus and twice takes charge to clean up Lockhart's
messes ("Finite Incantatem" and Vanishing the snake).

What we don't know is whether Dumbledore asked him to "assist"
Lockhart or whether it was his own idea. I'm inclined to think that
it's the first. If only we could see inside that shrewd and
calculating mind!

Carol, wishing that Snape could have taught DADA all along with no
DADA curse (I know; there goes the plot)

But