Old, old problem.

[Steve]

No: HPFGUIDX 151056

> Randy:
> 
> I always wondered why the AK on Harry does not appear in Priori 
> Incantatem list of spells?   
> 
> I am assuming that someone in this list has expounded on this at 
> length.  Any advice would be welcome.
> 
> Randy
>

bboyminn:

Of course, the answer is, we don't know. Maybe there is a plot reason
for it, maybe it is a mistake, or maybe it did come out.

Here is the problem with the FAILED AK curse, what would we see? We
wouldn't see Harry's ghost-like form because Harry wasn't killed. So,
really, what is there to see? Of course, we don't know.

But I speculate (...like you didn't already know that...)

First, not all spells are visual. The Pain Curse (Cruciatus) doesn't
emit any visual clues; you hear the screams of its victims. Well, what
if the curse or spell doesn't emit any visual or auditory clues? For
example, what would we expect to see or hear from the Reverse Spell
Effect of a Stunning curse? It doesn't seem to be much of a 'sight or
sound' spell. 

Second, Harry is not an expert at resolving Reverse Spell Effect
clues. I have always speculated that someone like Kingley Shacklebolt
who seems to be an experienced and very competent Auror could possibly
detect subtle clues of spells that would be completely missed by
Harry. Perhaps something subtle like a whisp of a particular color
smoke. Perhaps smoke density or the particular way the smoke behaves
would be the telltale clues of specific spells. 

Since the expelling from a wand of a trulu FAILED AK has never occured
before, I doubt that anyone including Harry would know what to look
for. From another perspective, think not about a Faile-AK in the sense
of the one Voldemort hit Harry with, but in the sense of one that was
successfully cast but it simply misses its target. Now ask yourself
what you would expect to see when that missed-AK came back out of the
want as it surely would? As I've implied, it would be something vague
and indistinct that only an expert would recognise.

What I am saying is that there may have been many more spells emitted
by Voldemort's wand than Harry was aware of, and that the Fail-AK
spell was there but its clues were to vague and indistinct for Harry
to recognise.

I have a method of resolving seeming inconsistencies in the books.
First, I assume that what seems inconsistent is actually true, and
then I try to invent an internal-to-the-story explanation for it. It
is entirely possible that this is an out and out error, but even if it
is, JKR will most like make up some explanation to make it internally
consistent.  

JKR did this with Marcus Flint which coined the term 'Flint' meaning a
mistake in the books. Marcus Flint stayed at Hogwarts one year longer
than he should have. JKR admitted it was a careless mistake, then
followed that with the internal-to-the-story explanation that Flint
was doing poorly in his studies and had to stay an additional year. In
otherwords, JKR does exactly what I do to explain inconsistencies, she
made it up. 

Until JKR clears up this particular event, the best we can do is
assume that what we read wass correct, and then invent explanations as
to why it was correct. My invention is that a failed-AK curse doesn't
emit any easily identifiable visual or auditory clues that Harry would
 have been likely to recognise.

For what it's worth.

Steve/bboyminn