Harry has already upgraded two existing spells: partial transfiguration and Patronus 2.0

In both cases, he achieved the impossible by ignoring what wizards believe and instead concentrating on his own beliefs.

What does Harry believe about Hermione that other wizards do not? He believes she is a purely biological machine, that there are no souls, and that a reductionist viewpoint is correct.

Therefore, in the right frame of mind, perhaps Harry can reparo a dead human (although canon!reparo cannot repair magical items properly, I wonder if it might restore Hermione without her magic, and if she might just be just as awesome without it.)

I loved this:

That's not how responsibility works, Professor." Harry's voice was patient, like he was explaining things to a child who was certain not to understand. He wasn't looking at her anymore, just staring off at the wall to her right side. "When you do a fault analysis, there's no point in assigning fault to a part of the system you can't change afterward, it's like stepping off a cliff and blaming gravity. Gravity isn't going to change next time. There's no point in trying to allocate responsibility to people who aren't going to alter their actions. Once you look at it from that perspective, you realize that allocating blame never helps anything unless you blame yourself, because you're the only one whose actions you can change by putting blame there. That's why Dumbledore has his room full of broken wands. He understands that part, at least.

Does anyone else run into the problem of frequently giving this advice to yourself and finding it useful, but struggling to find a non-awful way to convey it to other people? I don't want to get them to self-flagellate, but to look for what leverage they have and not worry as much about what it totally outside of their control. Stoicism seems like the main way people hit on this idea of responsibility in my social circle.

Would you guys agree that Harry is being unfair to Minerva regarding his Time-Turner? "But you thought it was your role to shut me down and get in my way."

At the time she had it locked, she was right: he'd been irresponsible with it and needed to stop abusing his new toy every time a minor problem arose, and there's not a hint that even Harry disagreed with that. You can't refrain from such corrective actions on the remote possiblity that limiting your student's options will do harm. Not-limiting an irresponsible student's options in the relevant way can also lead to harm.

This has only just occurred to me, but if the sole threat to the students was (as far as everyone knew) an ordinary troll, and it was daylight outside, and they were already in the Great Hall, then why didn't the professors just lead the students out of Hogwarts and into the sunny open before assuming defensive formation? It would also have the advantage of giving a group of casters long range on a melee attacker.

Just came across this in re-reading chapter 3:

The Killing Curse rebounded and struck the Dark Lord, leaving only the burnt hulk of his body and a scar upon your forehead.

Why a burnt hulk when the Killing Curse does no physical damage whatsoever?

It strikes me that the body doesn't match Voldemort's presumed cause of death, there are no witnesses of said death (since Harry's memory cuts out early), and burning a corpse is a classic way to render it unidentifiable.

Moving from considering evidence to speculation, it strikes me that the prophecy would make it incredibly easy for Voldemort to fake his own death - if he went to the Potters' house, killed the parents, placed a mysterious mark on Harry, and then disappeared, leaving a body behind, there is no way his enemies wouldn't take that as his death and the prophecy's fulfillment.

On a side note -

"But what I must actually tell you is that you will find the standard introductory text in the north-northwest stacks of the main Hogwarts library, filed under M."

First, I rather appreciate the comic relief, Eliezer.

... But second, what the heck are Memory Charms doing outside the--

Right. Hogwarts. Crazies. Nevermind.

Here's how I would have saved Hermione if I were Harry.

In an accessible but seldom visited hallway of Hogwarts, a rail-way sign reads 6PM to 5PM Express.

At 5:00, a boy materializes under the sign. He is wearing a rail-way conductor's hat. He is holding a trunk. His name is Harry Potter.

Conductor Harry puts down the trunk. He opens the lid. Inside his Trunk of Holding are wooden seats numbered 1 through 1000. All seats appear to be empty.

Conductor Harry yells "Arriving at 5PM! Please add one tally to your forearm now".

Silently, hundreds of people draw a tally mark on their arms.

Conductor Harry steps away from the trunk and the hundreds invisible passengers of the 6PM to 5PM Express disembark.

At 5:10, Conductor Harry closes the trunk lid. He stashes the trunk [EDIT] and Time-Turner in the Great Hall.

At 5:12, Conductor Harry burns his conductor hat. He draws one tally mark on his previously blank arm, and puts on his invisibility cloak. He sighs. He has a long day ahead of him.

...

At 5:30 in the Astronomy Tower, a smelly and disheveled Harry Potter pulls off his invisibility cloak. He is covered with hundreds of tally marks, and looks like he hasn't slept in days. He yells "Screw this, I'm done!", collapses on the floor, and falls asleep.

...

At 5:40, the original Harry goes to his room. He has done no time traveling today, and has no tally marks on his arm.

Original Harry locates his trunk and his conductor's hat.

At 5:45, Original Harry brings his trunk and hat to the hallway with a 6PM to 5PM Express sign.

At 5:50, Original Harry puts on his conductor's hat. Harry -- now Conductor Harry -- opens the trunk, steps aside, and yells "All aboard the 6PM to 5PM Express!. Please go to your assigned seat."

Hundreds of invisible Harrys silently climb into the trunk. Each Harry counts the tallies on his arm and sits in the corresponding seat.

At 5:59, conductor Harry yells "Last Call for the 6PM to 5PM Express!"

At 6:00, conductor Harry closes his trunk. He picks up his trunk, and flips his time-turner.

Using this method, Harry can get as much time as he wants to study obliviation, transfigure large objects, or anything else, all with a single twist of his time turner. That's more than enough time to learn to obliviate yourself (and maybe the Weasley) and fake Hermione's death.

"Other people have done huge amounts for me!" Harry said. "My parents took me in when my parents died because they were good people, and to become a Dark Lord is to betray that!"

(...) "So you are held back by the thought of your parents' disapproval? Does that mean that if they died in an accident, there would be nothing left to stop you from -"

"No," Harry said. "Just no. It is their impulse to kindness which sheltered me. That impulse is not only in my parents. And that impulse is what would be betrayed."

Chapter 20. It would seem Harry dodged a truly enormous bullet there.

"So you also don't think it's worth the trouble of holding me responsible..."

This could be interesting depending how she reacts later. I'm mostly expecting despair, but with a small chance of a heroic Minerva.

I suspect Quirrell's closing statements to McGonagall at the end of this chapter are not quite what they seem. I'm thinking of two in particular: the first, that he wants Harry kept away from the Restricted Section, and the second, that he wants McGonagall and Dumbledore to try to restore Harry's mood by any means necessary.

The trick to the first one is that he hasn't mentioned sealing off a certain other means of discovering arcane secrets at Hogwarts. Admittedly, Quirrell's suggested that it's probably blocked off anyways. But it might not be; even if the basilisk itself is gone, there might still be useful books. So it looks as though Quirrell is trying to push Harry into finding the Chamber of Secrets. There could be any number of reasons why - though the fact that it's a secret, hidden place at least partially exempt from the Hogwarts wards seems like a good place to start.

The trick to the second one is that McGonagall's way of cheering Harry up is actually going to be quite predictable: she and Dumbledore are likely going to try bringing Harry's parents to Hogwarts. Naturally, this opens up a whole world of possibilities for Quirrell; he could use them as hostages, kill them, Imperius them, or do any number of other nasty things if necessary. Or, if he's interested in understanding Harry better, he could use Legilimency to learn all about his background.

Multiple FF.net reviews suggest getting Harry's parents to try and cheer him up. But what about this, before the beginning of chapter 1:

Petunia married a biochemist

I predict Harry might realise his father can help him and find a way to ask/make him help. All the PCs and powerful NPCs around him want Hermione to be dead (either through action or inaction). If she can be revived, a professor of biochemistry might just have relevant knowledge, equipment, and the will to act. Come to think of it, even more so might Hermione's parents.

The biggest problem I see with this is that in the past, Harry felt his father did not take him seriously. However, he now has power his father knows not, and he has resolved to do anything to bring her back - he could credibly threaten his father's career, for example.

The second problem is that Harry may be too wrapped up with being responsible and needing to fix this himself to think of asking anyone else for help, but signalling him via Patronus is at least worth a try and costs little - "We are in a war situation, my best friend was just killed by a double traumatic leg amputation, but I've cooled her to 5 degrees and trying to work out what to do next. Ideas? I am deadly serious."