Breath of Life
Hermione had undertaken many complex projects in her time at Hogwarts, but this was by far the most difficult. Horcruxes were incredibly obscure magic in the first place, it was almost impossible to find books on their creation. The Room of Requirement had provided her with a book describing the process, one she suspected that Voldemort had used 50 years ago, but it gave nothing on how it worked. Herpo the Foul, an ancient Greek dark wizard, had been the one to work out how to make a Horcrux, and his notes were lost to time.
That meant she had to reverse engineer the arithmetic underpinning for making a horcrux. Very few wizards cared about how something worked, just that it worked. While Arithmacy was perhaps the least popular class at Hogwarts, to someone who'd taken grade school algebra it wasn't terribly difficult. Only archmages like Dumbledore and enterprising muggleborns really bothered to work with the language of magic.
It had taken her a week to actually work out that formula, and that was the easy half. Getting the equation was one thing, but what she really needed to do was figure out how to reverse it.
A great many variables can have an impact on an arithmetic equation. The time of month, a magical herb, wards, spells, potions, emotions. Horcruxes were fueled by hate, so the inverse equation had to be fueled by love.
This was gratifying, because she knew what 'the power the Dark Lord knows not' was supposed to be. It gave her hope that she was on the right track. It also significantly narrowed her hopelessly broad search to a few topics.
The Room of Requirement was a godsend, as was Harry's invisibility cloak, which allowed her to sneak into the restricted section of the library. With those two resources, she had practically limitless access to obscure tomes. Of course, she often had to reconstruct arithmetic formulas from any promising spell or ritual within.
After about a week of this, Hermione had found quite a few rituals that had some common elements with the horcrux negation formula. She couldn't quite keep her blush down when she realized all of these were either sex magic, or bonding magic.
It looks like Ginny may be a busy witch when I figure this out.
After another week of frustratingly trying to combine different rituals and spells together and getting nowhere, Hermione hit the jackpot. She found it in a book called Sex and the Soul, written by an American muggleborn witch in the 1970s. It was a purely theoretical ritual whose formula needed to be multiplied by seven to nullify a Horcrux.
She could scarcely believe it. After her initial breakdown when Harry had haltingly told her and Ron about the final Horcrux, Hermione had refused to even think about Harry… dying. She dove headfirst into her research, barely leaving time to ponder the consequences of failure. Failure wasn't an option.
So when she finally found the solution, the damn broke. Hermione burst into tears of relief. In fact, she hadn't even considered the implications of it until after triple checking her math. When she did, her face turned scarlet and she buried her head in her hands.
"Oh."
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After spending about ten minutes freaking out to herself, going on a long walk around the lake, and then collapsing in exhaustion in her bed for the night, Hermione was finally able to face to consequences of what she had discovered.
There were many types of bonds in the wizarding world; protector bonds, life-debt bonds, apprentice bonds, master-slave bonds, marriage bonds and more. The bond described in the book was the most intimate of all she'd read about, something the author called a 'soul bond'.
The book wasn't precise on the mechanics of the bond, because such a ritual had never been successful, but claimed that it must involve each of the partners sharing a portion of the other's soul within their body. This was illustrated by a yin-yang symbol.
The actual ritual involved arraying rune engraved stones in a circle around the couple on the night of a new moon and then having the couple make love- specifically, orgasming within a minute of each other. If the love between the couple was strong enough, the bond would form.
That in itself wasn't so bad, Hermione was certain that Ginny would go through with this to save Harry. Hell, Ginny would probably leap at the chance of doing this with Harry even if his life wasn't at stake. The bad part was that in order to negate the Horcrux, it needed to be done with seven different people.
Hermione tried to imagine telling Harry that. She couldn't. She tried to imagine telling Ginny that. She couldn't. This was why Hermione was making her way to Professor Dumbledore's office, for a second, unbiased opinion.
She laid out her reference materials and showed him her work; he nodded along in understanding as she did so. She couldn't help but notice, however, that his eyes had lost their characteristic twinkle.
"Ms. Granger, I am quite impressed by your work here, and I can certainly understand why you've gone through such an effort to help your friend, however" Dumbledore's tone dropped, and Hermione waited with baited breath for what he was going to say. Had she miscalculated? Had Dumbledore found an easier way?
"I believe this ritual you've proposed would lead Harry down a very dangerous path." The Headmaster continued seriously "The rituals involved would severely mutilate Harry's soul, perhaps leaving him completely unrecognizable to the young man we love."
"Professor, I believe the ritual leaves to soul intact. Only hate can break the soul. The part of the soul in the partner is still linked to the one in the main body." True there was some speculation there, but an act of love couldn't be used to split the soul. In addition, it didn't make sense that the ritual used to negate a Horcrux resulted in something identical to a Horcrux.
Of course, if it were the case that the soul was split in the ritual, it would make things much easier. All Harry would have to do was bond to Ginny and let his body die. Then they could find some sort of resurrection ritual to bring him back to his body. Unfortunately, Hermione was almost certain this wasn't the case. If the souls were linked and one partner was killed, it was far more likely that they both would die.
Dumbledore shook his head subtly "The soul is not something to be tampered with lightly. Soul magics are all but unknown, and one mistake could mean dire consequences in the afterlife."
"Surely an act of love couldn't have negative repercussions in the afterlife?" Hermione countered, her ire was rising at the Headmaster's rejection of her idea. It was almost as if he wanted Harry to die.
"Furthermore" Dumbledore continued "There are further complications you need to consider. How many witches would be willing to bond to Harry in such a way, even to save his life?"
"I would!" Hermione snapped, and as she said it she realized without a doubt that it was true. She'd do it. For Harry she would do it.
"Be that as it may, even if you could find enough people to partake in this bond, the consequences of such an intimate arrangement are completely unknown. You may all end up hating each other, and yourselves."
With each word he said, Hermione was growing more frustrated. Part of it was working tirelessly for a month and having all of it tossed aside on what she felt were flimsy grounds, but most of it was the fact that the Headmaster seemed so set on letting Harry die.
"But Professor" Hermione beseeched again "You told Harry that the power Voldemort knows not is love. This is a ritual powered by love! It all fits!"
Despite the passion behind her words, the Headmaster was unmoved. "I believe that particular line of the prophesy refers to Harry's ability to love compelling him to sacrifice himself for the good of those he loves. Such an action would be something that Tom could scarcely comprehend, and would ultimately lead to his downfall."
Hermione shook her head, willing the tears of frustration back, but they showed in her voice "I can't believe this. You actually want him to die."
"Ms. Granger, I don't want Harry to die. I wish there was a viable way-"
"There is a way! You just refuse to accept it!" She snapped, storming bitterly out of his office.
She was actually surprised at how sure she was of her course of action now, but when she thought of Harry, selfless, loyal, noble, clueless Harry, she realized that there had never been a choice. He was her best friend in the world, and when she thought about letting him die while there was something she could do to save him… she knew she couldn't do it.
She loved him. It wasn't quite the same way that Ginny did; it wasn't in the way that made her pulse race or eyes wander. Hermione had always had eyes more for Ron, if only he'd ever gotten his head out of his arse. No, Hermione's love for Harry was a steady flame in her chest, not flashy but certainly undying.
Ironically, Hermione had entered Dumbledore's office unsure of what she should do. The Headmaster's refusal had only galvanized her. Dumbledore would later come to wish he had used a more nuanced approach to discourage the brightest witch of her age.
When Harry had presented him with Tom Riddle's diary all those years ago, Dumbledore realized what must have happened. Young Harry had been dangerously close to the mark when he asked about his parselmouth abilities, and Dumbledore had had to mislead him a bit.
He hadn't wanted Harry to find out so soon. In fact, he'd been hoping to put it off as long as possible, but Harry certainly had a way of discovering things he wasn't supposed to. He should have seen it coming. This wasn't a burden he wanted Harry to bear yet, he wanted Harry to enjoy life as much as possible before… the end.
It had never occurred to him that Miss Granger would actually find an alternative.
This was very bad. Dumbledore had been hoping that after Harry sacrificed himself and completed the prophecy, he'd be able to finish off Voldemort himself. After all, the prophecy only stated that one must kill the other, if Voldemort killed Harry, it was perfectly within the bounds of the prophecy for someone else to kill him afterwards.
Harry wasn't anywhere close to ready to take on an archmage with decades of experience on him. It would take years for him to be ready, years of war and hardship and death. Having Harry sacrifice himself was sadly the best option. It would cut down the time of the war by years and save countless lives.
It was all for the greater good, of course.