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

[Carol]

No: HPFGUIDX 182679

Alla:

> > I believe that fact that Harry had a training with Boggart who 
immitates the Real Dementor has no bearing whatsoever on Harry's
ability to cast the patronus.
 
> Potioncat:
> But it had all the bearing in the world! If Boggarts could be made
to create that same effect for all the kids, then it could have been
used for all of them. It was only Harry who reacted the same way to 
his Boggart as he did to a Dementor. In fact, Harry reacted more
strongly to Dementors than other kids did.
<snip>

Carol responds:

Thanks, Potioncat. I agree, of course. As I noted in my earlier post,
Lupin believed that Harry needed a substitute Dementor to practice on.
Luckily for both of them, Harry's Boggart served the purpose,
duplicating the experience of facing a real Dementor without
endangering Harry. That's simple canon fact. 

While it doesn't affect his ability to cast a corporeal Patronus in
itself (most of the DA students could also do so) it certainly
provides an advantage in casting one against a real Dementor. (As
Harry says about the corporeal Patronus that he sends from Hagrid's
cabin, "I knew I could do it because I'd already done it.") Facing a
fake Dementor that sucks out the happiness required to cast a spell
just as a real Dementor would enables him to practice under realistic
conditions unavailable to anyone else.

If that didn't matter, Lupin would simply have taught him the spell
without bothering to procure a Boggart.

Beatrice and I apparently agree on the effect that the
Dementor!Boggart has on Harry. Where we disagree, apparently, is that
I think his facing the highly realistic Boggart substitute gave him a
distinct advantage (all too the good--he needed that advantage) when
it came to casting a Patronus against a real Dementor. She seems to
think, and evidently you agree, Alla, that he could have done just as
well having practiced conjuring the spell without a Boggart, in safe
conditions like those in the RoR.

Carol, who thinks that Remus Lupin would agree with me