Harry Potter and the Methods of Rationality

[Yakk]

A link might be helpful:
https://www.fanfiction.net/s/11174940/1 ... ant-Digits

[Pfhorrest]

Patzer also linked to the author's own site in the first post about it (on the previous page).

[Yakk]

Ah, I'm just blind.

Carry on.

[Pfhorrest]

So some other thoughts, speculation, very spoilery so spoilered:

Spoiler:

It looks to me like it's possible, that is to say I would speculate -- from the evidence of the references to Plato being a suspected ancient wizard because his writings on Form and Substance presage the language of of Free Transfiguration, and the actual passage from the Timeas quoted before one chapter, and from the magic that we see Goblins having done in the past when they had wands, what they called "will-works", and from Harry's science division researching the possibility that Free Transfiguration might be the most elementary kind of magic (and presumably Partial Transfiguration even more basic) -- that all of magic hinges on some kind of Platonic metaphysics that really makes it all boil down to prepackaged applications of free (and partial) transformation: the universe is an eternal infinite Substance and all the differentiated parts of it are just Forms imposed upon part of it (i.e. partial transfiguration), perhaps in nature by some kind of fundamental magical field that imposes the laws of nature as we know them, but that kind of imposition of Form can be manipulated by wizards somehow and used to break those laws of nature and locally impose new ones to reshape reality as they will.

If I may add my own editorializing: this would basically make the universe fundamentally informational in nature, not unlike a computer simulation, though it wouldn't necessarily imply that it is simulated, set inside some larger reality. Just that everything is, at its base, information -- Forms, with the Substance of the universe fundamentally unimportant, just a blank essentially featureless sheet to record that information on -- and that wizards are more or less hacking the universe and running new programs besides the ones that we call the laws of nature. I would guess that the latest prepackaging of these "programs" that modern wizards just run as users, rather than just partially transfiguring the universe from the ground up themselves, were set in place by the Eleusinian Mysteries before their fall to the muggle Caesars, which would explain the Latinate nature of most of the magical incantations the modern Wizarding world knows.

On a different note, some of this might have already been implied or possibly outright stated in HPMOR itself but it jumped out at me reading SD:

Spoiler:

It looks, from the Peverell's conversation, like Merlin's Interdict was imposed to prevent the medieval Wizarding world from suffering the same fate as Atlantis -- which I would speculate was possibly caused by Atlantean wizards using scientific methods just like Harry is, but with the benefit of being able to publish and record their findings across generations like Muggle science does and not personally apprentice each new wizard, to push magic so far that it threatened to "unmake the stars" and either triggered some kind of (super)natural cosmic censure or catastrophic accident that erased Atlantis from history, or else some forgotten hero took it upon themselves to erase Atlantis from history to prevent the end of the universe. (I think I recall comments from someone in HPMOR that the Atlanteans were thought to have erased themselves from history, so probably the latter.) I wonder, not recalling exact dates from the Rational!Potter verse well, if Merlin's Interdict might have been prompted by the early Renaissance, with the rise of science (including the science of magic) looking to Merlin like a threatened repeat of Atlantis; but I'm pretty sure Merlin was too early for the Renaissance to have prompted his Interdict.

Anyway, it looks like the Peverells themselves were trying to do something like science to magic, and unhappy at Merlin's Interdict for impeding them, and though aware of its purpose in preventing a repeat of Atlantis, they seem themselves concerned with preventing just such a catastrophe; which, from some of Harry's internal monologue, seems to be the same catastrophe Harry is in the process of both threatening to cause and attempting to prevent, himself. I would guess that the "Narrowing" inquired about by the Centaurs (I think it was them, cause they're so into prophecy) is a narrowing of the phase-space of possible futures, as that is similar to language used in Dumbledore's will to Harry at the end of HPMOR: there are very very few (and fewer still every moment) possible futures that don't result in the end of the world, and steering history through the tiny narrow space of possibility where it (history) doesn't come to an abrupt end is the challenge Harry's facing now, and what the Peverells were hoping to ensure.

On which note, one last bit of speculation:

Spoiler:

I'll bet that the mysterious The Three recently spoken of at the end of Arc 1 are the Peverells themselves, somehow still alive and trying to ensure the universe survives the risks ahead.

And now to invite speculation from others:

Spoiler:

There's a passage in some chapter somewhere were an unknown character, from a time period too early to have been Voldemort (around WWII, in the 40s some time), says something about not having a worthy adversary, and something about maybe creating one. Who do you all think that speaker was, and who was their adversary? The time period makes me think Grindlewald and Dumbledore, but I'm not sure why Grindlewald would want an opponent just like Voldemort did (or why Dumbledore would ever have created Grindlewald; unless, maybe, it was necessary because prophecy?), and I don't know how that would connect to the present story (it makes me want to think that Harry is the created adversary, but it was Voldemort who had that plan and the writer can't be him), other that perhaps somehow the parallels being drawn between Grindlewald and Harry with their consequentialist idealism. On which note, I lied above, here's my last bit of speculation: I think Harry is somehow either behind or at least complicit in the Malfoy's opposition to him. It just seems like a Rational!Harry thing to do, to set up someone to oppose and criticize him, a safety and a check, and also possibly perversely helpful in accomplishing his political goals (letting people see how benevolently the Tower treats those who see themselves as its enemies). I'm not sure if Draco would be in on it or not; it seems like it could go either way.

[raudorn]

Spoiler:

On which note, I lied above, here's my last bit of speculation: I think Harry is somehow either behind or at least complicit in the Malfoy's opposition to him. It just seems like a Rational!Harry thing to do, to set up someone to oppose and criticize him, a safety and a check, and also possibly perversely helpful in accomplishing his political goals (letting people see how benevolently the Tower treats those who see themselves as its enemies). I'm not sure if Draco would be in on it or not; it seems like it could go either way.

I think you might be right and would even go so far to say that it's not just intended/supported by Harry, but outright required. Remember that

Spoiler:

Harry is bound by the Unbreakable Vow to take no action that would endanger the world. Having an opposition that restricts itself to cosmically insignificant evil acts while keeping everyone on their toes about Harry is certainly a net positive as far as the vow is concerned. It also fits that the Malfoys (don't know if Narcissa is playing along) generally spout generic "We good, they evil" propaganda without a shred of actual arguments. Just like Moody is doing penetration test on the Tower's security, the Malfoys are doing routine societal maintenance by providing a pole to polarize against/for either side. You can't have two-body dynamics without, you know, two bodies.

[Whizbang]

All caught up. My favorite part so far was Pip's Day Out, especially the bit where he delivered the decrees to the centaurs.

And now to invite speculation from others:

Spoiler:

There's a passage in some chapter somewhere were an unknown character, from a time period too early to have been Voldemort (around WWII, in the 40s some time), says something about not having a worthy adversary, and something about maybe creating one. Who do you all think that speaker was, and who was their adversary? The time period makes me think Grindlewald and Dumbledore, but I'm not sure why Grindlewald would want an opponent just like Voldemort did (or why Dumbledore would ever have created Grindlewald; unless, maybe, it was necessary because prophecy?), and I don't know how that would connect to the present story (it makes me want to think that Harry is the created adversary, but it was Voldemort who had that plan and the writer can't be him), other that perhaps somehow the parallels being drawn between Grindlewald and Harry with their consequentialist idealism. On which note, I lied above, here's my last bit of speculation: I think Harry is somehow either behind or at least complicit in the Malfoy's opposition to him. It just seems like a Rational!Harry thing to do, to set up someone to oppose and criticize him, a safety and a check, and also possibly perversely helpful in accomplishing his political goals (letting people see how benevolently the Tower treats those who see themselves as its enemies). I'm not sure if Draco would be in on it or not; it seems like it could go either way.

Remember that wizards age much slower than muggles. Also, that Tom Riddle was born in 1926.

[Pfhorrest]

On which note, one last bit of speculation:

Spoiler:

I'll bet that the mysterious The Three recently spoken of at the end of Arc 1 are the Peverells themselves, somehow still alive and trying to ensure the universe survives the risks ahead.

It occurs to me now that it could also be referring to

Spoiler:

the Deathly Hallows themselves, rather than their creators.

[Pfhorrest]

Chapter 16 is up now. Is anyone else here besides me caught up yet?

It seems

Spoiler:

the Narrowing that the Centaurs referred to is even narrower than I expected, down to two and only two possible worlds, and this new child-adventurer is destined to somehow steer history through it.

[Pfhorrest]

does anyone else think that

Spoiler:

the "weaponized cognitive dissonance" from the Shichinin bonus chapter smells an awful lot of brainwashing? I mean, more so than obliviation and false memory already does. This is one tiny step shy of forcibly changing someone's opinion [it's making them falsely remember that they've already changed their opinion, and letting cognitive dissonance keep them from "changing it back" again], and is far closer to that than any real-life brainwashing techniques could possibly get.

[Whizbang]

For sure. Harry has a "for the greater good" problem.

[Whizbang]

Evidently Harry agrees and has worked a new plan.

Ah, the ol' "Recruit teenagers to save the world" stratagem.

[douglasm]

I haven't read anything of Significant Digits but the table of contents, but I spotted a chapter title "Azkaban". Now, correct me if I'm wrong, but I got the strong impression from HPMOR's final chapter that a) Harry was going to teach Hermione the Dementor-killing spell, b) Harry was going to bypass all debate on Azkaban, c) Hermione was going to just show up and commence the Dementor slaughter, and d) this was going to happen from start to finish within a few weeks of that chapter. Given all of that, how is it that Azkaban still exists to be the subject of a chapter at all? Does the story explain this discrepancy?

[Pfhorrest]

I haven't read anything of Significant Digits but the table of contents, but I spotted a chapter title "Azkaban". Now, correct me if I'm wrong, but I got the strong impression from HPMOR's final chapter that a) Harry was going to teach Hermione the Dementor-killing spell, b) Harry was going to bypass all debate on Azkaban, c) Hermione was going to just show up and commence the Dementor slaughter, and d) this was going to happen from start to finish within a few weeks of that chapter. Given all of that, how is it that Azkaban still exists to be the subject of a chapter at all? Does the story explain this discrepancy?

It's a flashback chapter covering the events implied to follow just after HPMOR, which have ongoing repercussions in the goings-on of the present-day of the story.

[Whizbang]

New chapter.

Not sure what to think. Mysteries within mysteries.

[Pfhorrest]

So the new chapter is finally getting to some of the really interesting stuff I've been looking forward to.

I wonder if Harry will put one of those fancy extended spaces into, say... a police box... and then put that in space... somehow wired to a time turner....

[jobriath]

I wonder if Harry will put one of those fancy extended spaces into, say... a police box... and then put that in space... somehow wired to a time turner....

Aaaaaaaaaaaaaaaaaa

I'm not even a fan of Dr Who but even I would get a huge amount of gratification from this plan.

[Whizbang]

spoiler for Significant Digits, Chapter Twenty-Eight: Sudden But Inevitable Betrayal

Spoiler:

So, Moody "got in". Congrats to the acknowledged best auror for getting past his own security system.

Is anyone else feeling a lack of conflict and suspense in this story so far? I mean, Harry has Draco working for/with him, so his greatest opponent is also his ally. After that the greatest obstacle is just the general reluctance of people to accept change and advancement¹, and maybe some questions on ethics on where the line "for the greater good" becomes "evil". Interesting topics, to be sure, but we need a more overt conflict as well, I feel. We got "The Three", but other than some mysterious rumblings they've been absent.

Also, this chapter title was highly misleading. You can stretch the word "betrayal" here to include Harry toward the two students, and vice versa, and Moody toward his "Even days only" thing, but in general everything seems to be running along nicely according to plan.

¹Admittedly a big obstacle.

[Tyndmyr]

Yeah...it's getting kind of deep into the details and the plotting, but without any real adversary. Kinda hoping it picks up soonish.

[jobriath]

Agreed :\ However, I'll be able to forgive the author anything due to his extreme use of diacritics, and random, uncalled-for, often untranslated Other Languages. I like that particular affectation.

[Whizbang]

Chapter 30

So...

Spoiler:

Harry, Hermione, and Draco all sitting around, congratulating themselves on a successful world domination and BAM! Bellatrix Black.

Finally, some overt evil to fight.

Also,

Spoiler:

Voldemort is back and you're gonna be in trouble.
Hey-la-day-la Voldemort's back!

[raudorn]

New chapter on Significant Digits and, woah, it's quite a thing. I admit I haven't quite understoof the plot twist in the last paragraphs yet, but reddit already has some possible interpretations. We also get treated to a description of that fateful Walpurgisnacht. However I wonder if there's more untold yet, since I don't see how Voldemort almost escaped that day. Tragic happenings, but it wasn't the cunning attack I thought it was.

[Pfhorrest]

Yes, SD continues to be awesome.

On a different note, I just realized something. There's this passage from HPMOR chapter 109, Voldemort speaking of a legend he believes relates to the Mirror:

I found written the claim that some Atlanteans foresaw their world's end, and sought to forge a device of great power to avert the inevitable catastrophe. If that device had been completed, the story claimed, it would have become an absolutely stable existence that could withstand the channeling of unlimited magic in order to grant wishes. And also - this was said to be the vastly harder task - the device would somehow avert the inevitable catastrophes any sane person would expect to follow from that premise. The aspect I found interesting was that, according to the tale writ upon those metal plates, the rest of Atlantis ignored this project and went upon their ways. It was sometimes praised as a noble public endeavor, but nearly all other Atlanteans found more important things to do on any given day than help. Even the Atlantean nobles ignored the prospect of somebody other than themselves obtaining unchallengeable power, which a less experienced cynic might expect to catch their attention. With relatively little support, the tiny handful of would-be makers of this device labored under working conditions that were not so much dramatically arduous, as pointlessly annoying.

It strikes me that that is remarkably analogous to what EY does for a living -- trying to build a friendly superintelligent general artificial intelligence. A machine that can harness enormous power and "grant wishes" -- do whatever humans ask of it -- but carefully built to not destroy the world in the process.

The Mirror is the magical equivalent of a Friendly AI. Perhaps an incomplete one, somehow, as the chapter continues on to say that the aforementioned endeavor was never completed and that's why Atlantis was destroyed anyway.

[raudorn]

It strikes me that that is remarkably analogous to what EY does for a living -- trying to build a friendly superintelligent general artificial intelligence. A machine that can harness enormous power and "grant wishes" -- do whatever humans ask of it -- but carefully built to not destroy the world in the process.

The Mirror is the magical equivalent of a Friendly AI. Perhaps an incomplete one, somehow, as the chapter continues on to say that the aforementioned endeavor was never completed and that's why Atlantis was destroyed anyway.

As I understand it, that was exactly his intention behind the analogy. It also served the plot by providing some information about the mirror.

While on the subject on the mirror, I still haven't figured how exactly it's supposed to do the things it's doing in SD. I think I have to reread everything in HPMOR again from the point where they arrive at the mirror.

[Pfhorrest]

While on the subject on the mirror, I still haven't figured how exactly it's supposed to do the things it's doing in SD. I think I have to reread everything in HPMOR again from the point where they arrive at the mirror.

If you're wondering how it's all in the mirror in the first place, that ties back to the weird geometry of the Tower spelled out in earlier chapters. The whole Tower is roughly triangular in shape, and every single room is an "irregular quadrilateral". It sounds to me like this is arranged so that, if you were to open all the doors to every room (and nothing was in there obstructing the view yet), every single point inside the tower would be within view of the... entrance... at once.

If you're wondering how being in the mirror allows the things that happened in that battle to happen, let me know when you figure it out because the best explanation I have so far is "because Harry wanted them to and this is his wish-fulfillent world". (Perhaps the "wish" "granted" in this particular mirror-world is that Harry's legendary snap-his-fingers-to-make-anything-happen power is real?).

[douglasm]

If you're wondering how being in the mirror allows the things that happened in that battle to happen, let me know when you figure it out because the best explanation I have so far is "because Harry wanted them to and this is his wish-fulfillent world". (Perhaps the "wish" "granted" in this particular mirror-world is that Harry's legendary snap-his-fingers-to-make-anything-happen power is real?).

The mirror is described in detail in chapter 109 of MoR. Reading over what it says there... the mirror's primary (or "most characteristic", to use the original wording) power is to "create alternate realms of existence". Obviously, the Tower is such a realm, contained entirely within the mirror. The general capabilities of the mirror are not fully described, but a major point is that rules can be set, and these rules cannot distinguish among individuals and (this part's partly speculation by Voldemort) must be related to the rule-setter's deep desires and wishes.

Combine all this with a line from the most recent chapter, "they even make the Killing Curse as dangerous as buttermilk so long as you're in the Tower", and it seems pretty obvious to me. Harry, deeply desiring to defeat death, set a rule that a spell whose sole purpose is to kill will not work inside the mirror-created alternate world. The Killing Curse, cast inside the Tower, I think merely knocks the target unconscious. It might even create an illusion of its normal effect while actually making the target undetectable (and still conscious and active), but that strikes me as dangerously exploitable if anyone figures it out. The finger snapping either is merely showmanship or is the trigger for something subtle and generally harmless. It can't be made specific to Harry snapping his fingers, so if it does trigger something the trigger needs to be safe for other people to trigger by snapping their fingers.

[raudorn]

So when you stand in front of the mirror it shows your Coherent Extrapolated Volition, basically "your strongest desire" with extra fancy philosophical additions. And if you know how, you can store things in the mirror with certain conditions for their release, as well as somehow enter the mirror. But how does this work in the case of the Tower? Is it basically the entrance and everyone entering the Tower walks through it like a portal? Or do people stay outside (unconscious?), while the mirror simulates what they would do in that simulated death-free world and then somehow manifests any changes to their bodies? And what does it mean exactly to be "in the mirror"?

I'm trying to wrap around my head around these questions, but can't answer them in any coherent manner. If I had to write a scripted videogame scene that takes a person from the outside up to the inner Tower, my best guess would be the following:

The entrance of the Tower is just the mirror embeded in wall to make it seemless. Harry stepped in front of the mirror and it showed a world of his CEV, which involves death being optional. Then he managed to shape the displayed world and convinced the mirror to make anything going in and coming out from that world behave as if there were a regular pocket of space behind that mirror. So when someone enters the mirror, they are "virtualized" and now exist in the simulated world within the mirror. But since the interface between both worlds behaves as if there was none, it's not obious. When they exit again, they are materialized in the real world with all changes that happened in the mirror world.

This might work, but does require Harry to have incredible control over the mirror and force it do only show his CEV, not the ones of other people. It also means that the entrance is the only ontological entrance to the Tower. You simply can't apparate into the Tower, because the real world (of SD) does not contain a space where any part of the Tower exists.

[Pfhorrest]

I think the actual space that is the Tower building really does exist in the real world, but the entirety of it is within view of the mirror, and so subject to its effects. We've already seen in canon HP that things happening in the mirror can affect what happens in the real world — Harry sees the philosopher's stone in his hand in the mirror, and then suddenly it's in his hand in reality — so when the entirety of the Tower is reflected in the mirror, those kinds of effects can be applied to everything inside the tower.

The only remaining questions I see are why only some mirror-things become real — canon Harry's parents didn't really return to life — and why the world in the mirror responds only to Harry's CEV, and not somehow those of everyone in the Tower. (Also, what happens if Harry leaves the Tower?)

[rmsgrey]

[...] why the world in the mirror responds only to Harry's CEV, and not somehow those of everyone in the Tower.

So long as it's responding to his CEV, presumably it can only respond to others' if that wouldn't introduce inconsistency?

[Pfhorrest]

I've got a theory.

The Mirror is not incomplete. It "grants wishes" by opening portals to worlds where those wishes are already true. And it is the reason that Atlantis was erased from history: the Atlanteans who built it, realizing that Atlantean civilization was on the verge of destroying the world (or worse), wished for a world where that was not so, and were granted access to a world where Atlantis never existed -- this world. Those survivors of Atlantis then became the first wizards of this world, perhaps the Eleusinian Mysteries or their predecessors (who perhaps codified magic into safe, user-friendly packages activated by spoken spells and wand gestures, hence the Latinate nature of most spell names).

Perhaps the Mirror itself is actually the Source of Magic in this world, as in the device through which whatever fundamental magical laws of the universe (that must supersede the physical "laws" magic routinely violates) are leveraged to produce the effects that we see wizards use. (And I still think free and more specifically partial transfiguration, and the Goblins' "will-work", directly accesses said fundamental magic, bypassing the prepackaged application of it into spells).

And perhaps the eponymous transmigration that gives the title to the book Harry is reassembling is the migration of said Atlantean survivors from their doomed world to this one.

Perhaps Merlin himself, apparently of Ancient Greek origin before his immigration to Britain, was one of those Atlanteans.

[Tyndmyr]

Well, it's a bit late for the actual threat to materialize, but hey, I'll take it. At least we've got some credible opposition now.

[douglasm]

I'm guessing the next chapter will include something like this:
Harry: You are meddling with things you do not understand, Meldh, and doing so for your own ambition and greed. That poses a risk to the world, which I cannot allow. *evict*
Meldh: WTF?

The chapter makes a point of noting that even Meldh can't break Harry's Unbreakable Vow, so to me that suggests it as a viable source of Harry resisting. Meldh just needs to do something that the Vow considers unacceptable first. So far all he's done is examine and comment on things, and some adjustment of unconscious biases might even be beneficial, but the moment he starts on the "Harry's my personal servant now" alterations I expect the Vow to object.

My impression of Meldh himself at this point is that he's blinded by prejudice (Harry is too, but Meldh is more and has less awareness of it), overly contemptuous of muggles, and competing out of his intellectual weight class with the raw power of ancient magic lore. He sees a lot of Harry's conclusions as ridiculous because he doesn't understand the reasoning behind them. Further, I think he wants to save the world because he happens to be living on it, not because he actually cares that much about it, so he views "saving the world" as more of something that restricts his available options for his real goals rather than as a goal in its own right. That makes him willing to push the boundaries on that restriction in ways that Harry would never accept, and I'm guessing that will prove to be his downfall.

[Tyndmyr]

Maybe? I mean, he seems pleased by the Vow. Serves his ends and all. And a complete breakout here by Harry would kind of remove all the tension and challenge. All these short threats that are quickly disposed of kind of kills the buildup. Narratively, Harry overpowering at this point doesn't seem like it really works. So, my guess is we're going to get some modifications to build the threat level, and re-explore "I recognize that I am confused".

[douglasm]

He does seem pleased by the Vow, what I'm suggesting is that he doesn't understand the Vow's full implications, particularly in light of Harry's knowledge of prophecy and muggle-like reasoning about the distant and galactic future and Harry's role, and will push up against it with something he doesn't realize is in conflict with the Vow until it's too late.

I don't expect Harry to outright win this encounter. Meldh actually being captured is exceedingly unlikely. Even if Harry escapes control, Meldh has already corrupted a substantial core of high ranking Tower insiders, and that's going to rip a severe hole in Harry's organization. I'm thinking Harry escapes by the Vow and an exceedingly hasty disengage, alerts Tower security, Meldh escapes via some bullshit OP ancient magic, and Harry's left with the nightmare scenario of figuring out who's been altered and how trustworthy they still are (and can he even trust himself!) and how to prevent it happening again, while Meldh brings information about the Vow and Harry's beliefs and prophecies back to The Three.

While Harry rationalizing his way to defeating the modifications later could be interesting, it would be difficult to pull off convincingly with the depth of alteration Meldh has been shown to be capable of, and Meldh getting out completely undetected would be a bit anticlimactic.

[Pfhorrest]

The fun thing about reasoned introspection is that, so long as Meldh does actually leave Harry's capacity to do that intact, it doesn't really matter what Meldh changed, because Harry's ongoing self-reevaluation will catch any problems introduced by Meldh and begin correcting them, and any non-problematic changes Meldh made don't need to be changed back so it doesn't matter if they're caught or not.

It's like, if someone magically changed all scientists' beliefs about how the world worked, and all our textbooks and journals and other records of them too, so long as they left the scientific methodology in place, we would eventually (possibly sometimes quite quickly!) discover the errors in "our" (the imposed) theories and update them with that new information, getting back to where we were before the intervention in time (more quickly the more significant the introduced errors are; if the dark wizard convinced us all that apples fall up, we'd fix that belief pretty quickly). And if any of the introduced changes were not actually errors, well, they don't need fixing, and all is well.

in before "but values aren't objective and don't work like that" -- one, no, you're wrong, but to moot that argument, harry is inviolably hard-wired by the Vow to value the protection of the world above all else, which was already his core value to begin with, so the introspection on any changes to his values and their possible conflict with the unchangeable values imparted by the Vow will bring him back to his old values in time anyway.

[Jorpho]

It's really quite tempting to put things down and start reading this, but then it occurs to me I'd probably be much better off waiting for it to reach its conclusion.

The first anniversary of HPMOR's conclusion is March 14. Maybe we'll finally see those omake files.

[douglasm]

Interesting.

Spoiler:

Harry's controlled, but aware of the control. And Meldh is disconcerted by this awareness. My judgment of Meldh as someone competing out of his intellectual weight class is reinforced here. He's not stupid, but he's not up to Harry's level. How he got into the Tower was quite clever, and he did a great job of keeping a low profile on his way to Harry, but now he's using Eguestimentis like an all-purpose hammer with no precautions against its shortcomings. And it does have shortcomings, at least the way he's using it. The fact that Harry et al showed guilt in trapping Draco proves that.

A properly careful takeover would want the subjects' behavior to be as indistinguishable from normal as possible. The best way to ensure that is to make it so even the people helping you do the takeover are unaware that the takeover is happening, and that they believe their takeover-related activities are actually part of some other, more normal, goal. Meldh has the mind control magic necessary to do such a thing - he even used it in exactly that way on his way in. But now he's switched to full bore "I am your Master now, slaves!" mode.

I see two potential paths from here.
1. Unbreakable Vow:
The Vow evidently didn't act up during the takeover of Harry, but Meldh apparently went with a general purpose "obey me" alteration and that wouldn't conflict with the Vow without Harry knowing what Meldh's goals are. Now Harry is starting to learn about what Meldh wants, and that could easily run into Vow opposition. In fact, it might already have happened - the moment when Harry was surprised by his own words could have been the Vow kicking in to prevent the risk of revealing resistance to Meldh. "Throwing things into the sky" is a critical part of saving the world's people from the inevitable eventual destruction of the planet, after all, and Meldh had just then expressed explicit opposition to it.

As Meldh continues to oppose various measures that Harry knows - not thinks, but knows - are necessary for saving the world, Harry could come to the decision that, for the sake of the world, Meldh must be stopped, despite the "obey Meldh" bias implanted in Harry's mind. This could then be resolved either relatively quickly, with Harry doing some elaborate maneuvering within the Tower to outwit Meldh, or a more drawn out conflict, with Harry leaving the Tower to amass forces and plan in a secret location, turning Harry vs Meldh into a long running major plot arc.

2. Triumph of Rationality:
Harry explains his reasoning in depth, at length, and quite persistently, to Meldh over some extended time period. Meldh tries to shut him up, even explicitly telling him to stop, but Harry disobeys. Meldh, knowing about the Vow and perhaps realizing that this disobedience springs from the Vow, eventually is convinced and changes sides.

The latter option might be more in the story's theme, but I think the former would be a more entertaining read. Perhaps they could be combined.

[jareds]

Harry's Vow does not compel any positive action. It could certainly be the reason that he opened and closed his mouth several times without saying anything, but it cannot have forced him to say, "Yes, sir!"

[jobriath]

I'm perhaps being dense.

Spoiler:

When Meldh was in the Harrybrainscape, is it clear what he was referring to when he exclaimed "you realised this and discarded it?!"

[Pfhorrest]

It wasn't clear to me either.

[douglasm]

I'm perhaps being dense.

Spoiler:

When Meldh was in the Harrybrainscape, is it clear what he was referring to when he exclaimed "you realised this and discarded it?!"

I think that was intentionally vague. Presumably it was some fantastically effective avenue to power, with a difficult to understand and/or low-chance high-value risk involved. Another possibility for this plot arc's resolution is Meldh using whatever idea it was and falling afoul of the risk Harry discarded it for.