Harry's DADA skill was Re: Albus and Gellert/Voldemort's Power

[Carol]

No: HPFGUIDX 182667

Carol earlier:
> > Which is exactly my point. Harry's Boggart, shared by no other
person we know of, allows him to practice (safely) on a highly
effective substitute Dementor. No one else has that advantage. All
they can do is cast learn to cast a Patronus in the RoR, where it's
easy to find and concentrate on a happy memory. It's another matter
altogether when a Dementor (whether real or a highly realistic Boggart
substitute) is sucking out the very happiness that's required to
conjure the Patronus. The Boggart, scary as it is, can't *really* suck
out his happiness, much less his soul, any more than Boggart!Snape can
really take points from Neville or a Boggart mummy can really do
whatever mummies do. 
> 
Beatrice responded:
> Not to quibble over such a small point, but I agree that the fake
Dementor probably cannot suck out Harry's soul - but it does  an
excellent job of sucking out Harry's happiness...so I don't think 
that you point really holds up here.  <snip>

Carol:

Yes, *of course,* it does an excellent job of sucking out Harry's
happiness. That's what makes it such an effective substitute for a
real Dementor.

Harry's ability to cast a Patronus against a real Dementor that is not
only sucking out his happiness but could also, if given the
opportunity, suck out his soul, has been gained through practice with
a Boggart!Dementor that can *also* suck out his happiness (but can't,
fortunately, suck out his soul, which is why he can safely practice on
it, especially with Lupin there to banish the Boggart and hand Harry
chocolate.)

It's like the difference between driving lessons that safely simulate
real driving conditions, complete with car crashes and other dangers,
and those that just teach a kid how to turn the steering wheel, look
in the rearview mirror, and put the car in gear, and then sending them
both into traffic with no adult in the car with them. The second kid
might be able to drive a car on a real street, but the first kid would
have a great advantage over him in having already faced and survived
dangerous conditions in a realistic simulation.

Before the lessons, Lupin says, "I'll have to think carefully about
how we're going to do this. We can't bring a real dementor into the
castle to practice on" (PoA Am. ed. 235).

At the beginning of the first lesson, he tells Harry that the Boggart
he's found is "the nearest we'll get to a real dementor. The boggart
will turn into a dementor when it sees you, so we'll be able to
practice on him" (236).

After Harry has practiced the incantation and cast a wispy,
noncorporeal Patronus, Lupin says, "Very good. Right then--ready to
try it on a dementor?" (238).

And, as you say, Harry experiences exactly what he would face if the
Dementor were real, a "wave of piercing cold" and his mother's voice
followed by Voldemort's. Exactly as if he were facing a real Dementor,
Harry loses consciousness. Lupin, who has apparently sent the Boggart
back to its container, gives Harry chocolate, advises him to pick a
happier memory, and they try again because Harry is afraid that the
Dementors will show up at the match against Ravenclaw and cause him to
fall off his broom (238-39).

The "Dementor" comes at him again and the experience is repeated. This
time he hears James as well. He finds a third, happier memory, the
"Dementor" comes out, the room becomes cold and dark, but he's able to
cast a huge silver shadow against his Boggart Dementor, which Lupin
then gets rid of with the Riddikulus charm (242).

Additional practice against this highly effective Dementor substitute
enables Harry to cast a Patronus against the real thing.

If you still don't see the advantage of learning to cast a Patronus
using a Boggart Dementor (available to no other student) against a
realistic Dementor substitute, I won't argue with you. But it's no
surprise to me that Harry can cast one after those lessons with Lupin,
thirteen years old or not. If any other thirteen-year-old wizard of
average or above average ability had private lessons with a competent
DADA teacher, combined with Harry's motivation (the Dementors affect
him more than others because of his background and interfere with his
Quidditch games) and a Boggart that substitutes for a real Dementor,
sucking out the very happiness required to cast the spell without
posing the danger of practicing on a real Dementor, they'd probably
learn, too.

Carol, who doesn't understand your objection to her argument since you
agree that the Boggart sucks Harry's happiness as effectively as a
real Dementor without placing his soul in jeopardy