Thought some more, and I have some ideas.
One of the realizations I think I had is that magic recognizes divisions where there are none. PT being the prime example, but also the ability of armor to block spells. PT relies on removing the caster's understanding of divisions; what if there is a way to add divisions? If Harry can convince himself that his skin is not part of himself, will it block spells the way thick leather does?
Conversely, are there other divisions that open possibilities if removed? Like between people and the ground, or people and people?
Most thinking I'm reading about uses PT to create a weapon with which to attack, but attack is not the goal. Escape is. Means of escape fall into a few categories, I think: Figuring out something like Apparition on the spot, quantum tunnelling, or Newtonian. Right now I'm just going to think about "newtonian" - It's just as ridiculous for transfiguration to not include velocity as it is for it to only effect "discrete" objects. Can Harry simply add enough velocity to himself to escape? (Adding acceralation doesn't work, as enough to escape fast enough probably squishes him)
Here are crazier things:
There's good proper acausality in this universe. Coma-tea, time-turners, and the Stars spell. What's going on there? Is there some way to use that?
At first, there is evidence that changes to the body and brain effect the mind. But, there's also a pile of evidence that, under circumstances, it doesn't - Horcurxes, and both resurrections. What if Harry can detach his life/magic from his body?
I think a big question here is "what kinds of magic, if any, are available?". Answer might be "none". Partial transfig takes too long, everything else requires motion.
That seems to leave to possibilities:
In other words, no known magic is useful in this situation.
Does that seem reasonable? Does anyone remember a form of magic that doesn't require motion or time?
(Dinner interrupted)
Sorry, didn't go into recommended courses of action.
/If/ Hermione is innocent under the above scenarios, then you need a way to detect magic use, either via an examination of what Hermione has cast by looking at her wand, or an examination of Draco for magical traces.
If she isn't innocent, or, rather, no evidence can be found that shows innocence - they key is Lucius and his rage. He's acting particularly irrationally because it involves his son, so Harry may be able to do something with regards to Draco. The concept of "reasonable doubt" is almost certainly not codified in Wizarding law, but the concept probably exists. The problem with applying it is again Lucius' rage.
So - Our goal is to return Hermoine to Hogwarts in a reasonably healthy state - say, no damage that won't heal in weeks. The issues standing in the way are that is popular to hate on Hermione, and the Lucius is out for blood, /potentially/ on his son's behalf.
Harry could take actions to make hating Hermione unpopular - other comments suggest Harry challenge duels, or threaten to leave the country. Alternatively, he could promise favors; on the gripping hand, he could threaten duels and promise favors.
Lucius' rage is unlikely to be abated by any interference from his son - he already considers Draco "compromised" with regards to his new opinions on Muggle-borns. Any information regarding Hermione as, in fact, wizard-born wouldn't work either - he'd be enraged anyway, although he'd likely turn towards other avenues...
Which makes me think - Hermione, as a muggle-born, holds a status somewhat similar to an orphan, and is thus presumably adoptable. In such a case, Harry (or another friendly noble house) may be able to adopt Hermione, take the blood-debt on the House, and pay it another manner... such as Harry, who Lucius has reason to hate due to Draco, going to Azkaban instead. (And summarily destroying it)
My original idea for abating his rage is actually Fawkes - If you could get the Pheonix Calm on Lucius, he may be able to think rationally - he'd still demand punishment, but maybe then it'd be something in line with the crime.
Hmm. I'd like to share all this, but I'll keep thinking.
Chapter 80 -
Damnit, lost my nice long post. Here's a short summary:
If this a plot designed by Quirel, it's to help Harry. If this is a plot to help Harry, my guess is that it's via the governmental destabilization that will result - Unrest will be caused by the ruling, a lack of trust in the sanity of the government, and this just gets worse when Harry does something drastic to get her out, like taking the whole thing out. If it's a legit attack, not sure what to do or what will happen.
As for the events themselves, I think they happened. "Oblivation cannot be detected by any means" - Hermoine did cast the B-C charm, and then reversed/treated it... the posited villian then comes in, restores the curse, and oblivates the memories of reversal/treatement. As for getting her to do it in the first place? Muggle drugs to enhance paranoia and aggression - wizards wouldn't check for it, but Harry would.
The other best possibility I can imagine is that Hermoine cast some other spell as a sneak-attack, and then someone just changed that memory - a work of a few minutes, if that.
Both of these particularly square with Hermoine's statement, paraphrased, that she woke up to realize what she'd done, not stayed up all night aggravated by it.
I think I should give this a go. I'll be coming from Santa Monica, and am likely to be late.
So, release of magic doesn't require movement. That's something.