Year Two
The Vagaries of Magic (Interlude)
Magic is a many-faceted thing. To understand the world Harry Potter lives in, the world Harry Potter creates, knowing the nature of magic is eventually necessary. Though there are many so-called "schools" of magic—transfiguration, charms, runes, and the obnoxiously nebulous "Dark Arts"—broken up into categories, those are simply arbitrary mnemonics, created for ease of learning. The origin and source of magic are a mystery as old as time, but as mankind has come to use it and manipulate it something important became apparent to the most perceptive witches and wizards. At its core, magic is about just two things: intent and focus. Almost any question about magic can be related to these two simple truths.
For example, why are some wizards more powerful than others? Intent and focus. Tom Riddle is an exceptionally bright and talented wizard to be sure, but his true magical force comes from the torrent of intent put into each spell. Every curse and jinx he wields has the force of every fiber of his being, poured into want and released in power.
Albus Dumbledore, his opposite in the first war, is his opposite in this sense too. Dumbledore certainly has strong latent intent as a wizard, but his real strength comes from his focus. For example, if Tom Riddle were to hastily conjure a chair, it would be adequate and possibly comfortable if he so desired. If Dumbledore did the same, the chair would be unique in every way and ornately detailed, down to the phoenixes carved into the redwood armrests and the garishly decorated padding—with no real effort on his part. It is just as he imagined it.
This is why a witch like Hermione Granger could never be a truly powerful magic user. While her inborn brilliance and focus are beyond equal in all Britain, her intent is sorely lacking. Her years of Muggle schooling and a penchant for academia made magic an intellectual exercise for her rather than a practical one. For her, learning new spells is about the fact that new knowledge was acquired and not what can be done with that knowledge.
But what does this have to do with Harry Potter? Everything, of course. Harry Potter's life is the unwelcome convalescence of some of the most powerful magic ever wielded: Horcruxes, blood wards, Fidelius Charms, on and on ad nauseum. Ironically, the most powerful type of all is not even real magic; in 2021 it was discovered that prophetic trances are actually a symptom of a type of schizophrenia only developed in magical people, more prevalent in females than males.
Whoops. Sorry about that Harry. Honest mistake.
So Harry's all mixed up with potent magics flowing in and around him, right? Some of them are directly conflicting with one another, all the while his magical and non-magical development was still ongoing, when he encountered Voldemort and the Stone. When the power of the Stone forced its way through the link between the two wizards, the first thing it interacted with was its magical intent antithesis: the Horcrux.
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A Horcrux is a bit of magic that requires both intent and focus, but much more of the former. Human beings are inherently social and defensive of one another over any other species, and the highest level of disconnect one can get from their own humanity is to violate this basic instinct, to kill another person. This is why some of the most powerful magics are rooted in human sacrifice. The Horcrux takes this and focuses many intents—greed, fear, contempt—to break one's soul, one's humanity, apart.
As Riddle created more Horcruxes, he became more proficient. His first was crude and poorly made, the heady flow of his first kill still lingering in his mind and disrupting his focus. This mistake meant it became more than just a place to hide a piece of his soul and gained a level of autonomy all its own. Over the course of a decade it eroded the will of Lucius Malfoy and compelled him to sneak it into Hogwarts, the only other place it knew. Riddle never made the same mistake, his next five all being perfectly made and each more powerful than the next. The ones placed in objects were able to defend themselves with crude but deadly Dark Magic, while the one in the snake grew it to unnatural proportions and imbued it with magical power of its own.
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Riddle's last Horcrux was the most powerful. It was the first recorded incidence of a Horcrux being made out of a human being, conferring abilities on its container in an unheard of fashion and linking it with the original soul. When this bastion of incredibly powerful magic rooted in intent marred by "death" was met by the even stronger magic of the Stone in the intent of "life", the result was catastrophic.
A person's mind and their magic are both inextricably linked and mutually exclusive. Magic can cause both physical pain (such as with the Cruciatus Curse) and magical pain (such as in cases of magical exhaustion). When Harry's mind was caught in the crossfire, he was forced to experience both at once, in horrible intensity. The human brain is only capable of experiencing so much pain before it shuts down all non-essential functions, such as in the case of Frank and Alice Longbottom. Harry would have been left like them forever had the Stone's power not finally overcome the Horcrux.
He was left without magic or mind, but living around vibrant ambient magic allowed Harry to pull from it, as Dumbledore predicted. The "inextricably linked" worked in his favor this time and slowly but surely his magic repaired his mind, starting with the simplest connections. The last thing to return, then, must be cognition—conscious thought. Until then, Harry is at the mercy of his own self.
Uh-oh.