The real Quirinus Quirrell was most likely lobotomized long ago, to become the Defense Professor’s “zombie mode.”
The going theory is that Monroe and Voldemort were the same person, and that the real Monroe did not return from Albania. Usually, this is because the Defense Professor wanted to manipulate Wizarding Britain to concentrate power in the Ministry, and then put himself at the head of it.
I strongly doubt that the Defense Professor intends to die with his body. The real Quirinus Quirrell, however, probably will.
Intrism
You could probably make Arresto Momentum relatively safe by having it choose between the caster’s frame of reference and the earth’s (at the caster’s position) based on whichever results in the spell doing less work. It’s still dangerous, obviously casting it on someone else’s moving vehicle would be a bad move, but it avoids making anything go “zoom” in a privileged frame of reference.
Arresto Momentum itself looks very safe on first view, and nobody warns about, say, casting it while inside a moving vehicle
Every single casting of Arresto Momentum ever was performed on a moving planet, which resulted in no issues. It’s possible that casting from inside of a moving vehicle to outside of it might result in problems, but I strongly doubt that it’ll do anything which would seem bizarre from the caster’s frame of reference.
I don’t think Rita Skeeter is good evidence. It would not do for Quirrell to have Harry notice an unexpected, strange burst of magic when he’s trying to quietly kill someone; Quirrell would have found a way to suppress it, if it had existed. (It’s also possible that her Animagi transformation suppressed the effect.) The absence of the burst of magic in Harry’s parents’ deaths, on the other hand, has led me to an inverse suspicion to yours...
It is notoriously difficult to trail someone who is wearing the True Cloak of Invisibility, with added anti-detection charms because apparently the Deathly Hallow just wasn’t enough.
Or, Harry is summarizing a wide variety of observations on the topic of puberty in a pithy and relatively un-embarrassing fashion. We don’t know Harry’s actual basis for claiming that he hasn’t yet begun puberty, but his comments on the subject are just a little too flippant to be the complete truth.
The problem is that “bypassing the Interdict” is not, on its own, useful; it’s only valuable if Harry happens to have written notes on powerful magic spells that are censored by the Interdict. Apparently, there’s a loophole allowing Interdict-restricted material to exist (wizards can keep notes for themselves, implied by chapter 23), but it seems unlikely that Harry would be able to get ahold of much of it. (Possible exception: Bacon’s diary? Quirrell didn’t think Bacon found much of interest, but he could be wrong.)
Related: since Muggle physics can apparently contribute to powerful magics (see: partial transfiguration) would the Interdict apply if Harry ever wrote a physics book? What would the Interdict do if a Muggle happened to accidentally write (presumably as fiction) the details of a powerful magic spell? Can Muggles read Interdict-restricted works?
Time-Turners are in frequent and authorized use by a fair number of students, as well as Dumbledore himself and possibly other staff members. Any such ward would be constantly triggering, for no particularly important reason. Even if one exists, I can’t imagine that Dumbledore pays much attention to it.
Dumbledore is only looking for Hermione. There’s no reason for him to be much interested in Harry’s magical devices, beyond proving that they aren’t Hermione. The portkey was only mentioned because it was a part of Dumbledore’s body search; the Time-Turner, presumably, wasn’t on his body.
Inferi appear to be common knowledge; they’re cited in casual contexts in chapters 70 and 78, by Lavender Brown and the narrator respectively.
Harry can return to the present via the long route, if necessary. It doesn’t appear that anyone bothered to check for extra Harries in the morning, so he wouldn’t need to do anything more exotic than hide in the washroom before the previous Harry iteration got there in order to fool the Professors.
Remember that Harry had just been hastily awoken long before his accustomed time. It’s not unreasonable for Harry to be behaving a little bit awkwardly, and it certainly isn’t enough of a tell for Dumbledore to draw any conclusions.
What does seem to be a bit of a tell is his strange behavior around the ring; he seems to deliberately create tension before the ring is verified in order to, apparently, play for sympathy afterwards.
Remember that Harry only needed to keep Hermione in the ring until after his stuff was searched; it strikes me as improbable that Dumbledore will demand to search the gem again. (Of course, having Hermione’s body magically appear would still be a bit awkward, but the losing-a-finger part was the only one which I would expect to truly scare Harry.)
I still don’t think the ring theory is correct, though. Harry has no reason to bring Hermione’s body with him to the meeting; at best, it is an unnecessary risk. There’s a Time-Turner theory elsewhere in the thread that seems far more elegant to me.
(Ch. 94) Wow. That discussion we got after the meeting was the first legitimately silly theory we’ve heard from Harry, and I’m astonished that the Professor humored him. Hopefully this is a symptom of sleep deprivation.
If I had to guess, I’d say Quirrell. He’s a person of very many identities; there’s no reason that the first one necessarily was male. The only problem with that is that Dumbledore still seems to think Voldemort was Tom Riddle (see Chapter 79) but as Voldemort is said to have changed twice in his career as a Dark Lord (after murdering the House of Monroe, and after the last Monroe vanished) it’s possible that he was replaced and Dumbledore didn’t notice.
Her “reason and maturity,” in canon, is basically playing the role of a responsible young girl. Rowling seems to think this is impressive; obviously, Eliezer does not.
Of course, the attacker could also have chosen to kill Draco slowly in order for the ward circumventions to go unnoticed...
“Ward” almost certainly refers to the spells McGonagall cast to protect herself and Harry from public view.
The House Points are more of a way to formalize Minerva eating crow for all the students that broke the rules and acted when the situation required it. And, of course, most of the points talk was really about extending them to more students, which was extremely necessary for Harry. The Neville talk was probably the least justified, but there is a shard of importance in that Harry had to forgive and defend Neville during it.
My estimate of Trelawney in Methods has, for quite some time, been that she may or may not be good at formal Divination, but that she is a terrible teacher and an excellent seer, and that Dumbledore keeps her around primarily for the latter reason.
Just so you’re aware, it’s fairly easy to dump the script files from Umineko if you’d prefer to read it that way. There’s also an auto mode, which is irritatingly slow, and a skip mode, which I used to skim through the art after reading the script file.
You might prefer the story of the Higurashi visual novels to the anime, and the English release has a configurable (and pleasantly fast) auto mode.