Disclaimer: Standard wording applies; all glory be to JKR.

A/N: I've been working on this story for a little over a year now and as I near the end of it, I decided to go ahead and publish the prologue. I suppose it's a rite of passage for any HP fanfic writer to do a time travel fic, but I had resisted for over a decade until I was struck with this idea on one of my commutes home. I have a long ride twice a day- an hour each way- and it was on one of those drives that this came to be. I hope you enjoy the preview; the full story should begin being published around mid-February.

Trigger warnings for descriptions similar to self-harm in the below; this is rather darker than what I typically do.

Entanglement

Prologue

The Sacrifice

1998 March 11

She remembered glass and an outstretched hand, the shock of red hair and desperate fingers; a voice shouting her name and brilliant pain scoring through her blood and into her mind. A body tackled her to the hard marbled floor, arms heavy around her waist. There was pain and darkness, and she knew she was falling, the air cold and brittle, and the ground, as it met her, was softened by the warmth of another.

She saw dark hair and felt heat on her cheek, and when Hermione next awoke, it was to sun on her skin, cool earth under hand, and Harry's shuddering gasps.

It was morning still when Harry died, his blood too thin to clot, the curse too heavy with dark magic to cleanse. He sputtered and shook, his lips moving but voiceless. She felt little of the throbbing from the dripping letters on her forearm; she noticed nothing of the tremors that left her hands shaking and spine aching. Harry's eyes grew wide and unseeing as something darker and colder than death overcame him. The scream that followed his last breath, the shriek of rage and wrath and boiling pain, informed of a worse truth.

Her first true friend, the part of her heart that she allowed a piece of her soul, had been a horcrux.

It took almost two more months of living off of stolen scraps from Muggle kitchens, of sleeping under tarps magicked with warmth and ignore-me-please spells, and of dodging the Snatchers, their hunting hounds, the Cŵn Annwn, howling at her heels and promising her death, before she came to her decision.

Potterwatch had ceased its broadcasts two weeks earlier, the last message an entreaty to all above and below to leave- to run- to seek sanctuary with the MACUSA or escape far beyond the continent to where Voldemort's reach had yet to penetrate. She knew little of the Weasley twins' final hours, only that the next broadcast echoed of an intermittent cackling and feminine hiss of pleasure.

Three more months passed before the potion was readied. Her wrist ached for days after she finished with the required cutting, her blood darker than she had imagined and the pain a numbed throbbing that matched her heart beat. The potion was not the sort Dumbledore would have approved of; the ingredients had demanded sacrifice and hate, but she tempered its intent with thoughts of her friends and family.

Hermione could not turn off the love her heart had for those she wished to save, to bring back and return to her world, and in the end, the potion was different from what the coverless book promised. She carried it around her neck, its small mouthful of promise protected in an impervious vial, and like the locket, it whispered to her visions of an alternative future and changeable past.

She heard the howls of the Cŵn Annwn as they neared, heard the pounding of their spectral paws along the ground, and her arrival in the sacred grove, the blessed trees faint and white in the passing light of twilight, was more stumble than step. She cut into her skin a second time, her fingers trembling as she pressed her bloodied palms along the trunks of the trees.

Her blue flames ate at the wood, purifying her offering and leaving burnt etchings of her runes in their wake.

The hounds circled the grove, their wizarding counterparts not far behind, and Hermione knew that her moments were now but seconds. She fell to the grove's center, her knees holding enough strength to grant her a kneel. In her memory she found her earliest thought, her earliest piece of happiness and love. She saw her parents, young then, and unhampered by a daughter gifted with things too wondrous and awful to behold; she saw her parents embracing in the daylight, their bodies dancing to a forgotten tune from the radio. She saw herself at their feet, fingers raised skyward.

She closed her eyes and lifted the vial to her mouth. Her lips whispered the incantation, and in mirror copy of her six-year-old self, she too reached toward the sun.

"Take me back," she begged. "Let me fix it."

The melody grew louder, and the dampness from her wrist grew heavier. The hounds, in their dark hunt, howled and snapped, and distantly the shouts of the Snatchers caught her ears.

But the song was stronger; her spell held. The potion, deep within her now, pulsed, and expanded until there was only a brilliant light, enveloping all.

The air stilled, and the trees silenced. The hounds whimpered as even the stars dimmed in a stammering of power and chasmal change. Their masters cowered in a sudden nameless terror. In the vacuum of existence, a piercing cry broke into the stutter.

A small child materialized from the grove's center, no more than six, her brown hair thick and unkempt, and her dark eyes frightened and pained.

Dumbledore would never have approved of sacrificing a child, but to Hermione Granger, the loss was less murder than it was suicide. Better the world lose a single child- better the world lose her- than it lose itself.

A life for a life, the spell demanded; she had only the will to offer her own.

1986 January 27

Remus Lupin could remember, once a long, long time ago, thinking that perhaps one day he would get used to the pain. He would hope, in the first moments of ripping and splitting, of his bones snapping and re-shaping and his body contorting into a monstrous mockery of his form, that there would be a future in which his mind would no longer feel the horror of the change. He had never hoped for a cure- he was never so foolish as that- but to reach a point in which perhaps he might become used to it.

A point in which perhaps he might accept it, even.

Being a lycanthrope.

Being a monster.

It had been years since he last visited that hope, and in the early morning hours after his body had returned to itself, he felt grim satisfaction that he had done away with such thoughts and pinings long ago.

What he could not change-

What he could not control-

There was only the pain, and as long as he could keep that pain to himself- as long as he could go without infecting another, or hurting another, then that was achievement enough.

Remus stretched carefully, feeling the alien movement of his human bones beneath his human flesh, and reminded himself that these sensations- this skin and muscle and tendon- were normal and real. The wolf part of his mind was slow to fade, and it rejected the weakness of its host. He closed his eyes and recalled the feel of his arms, the pull of his legs; he traced over the span of his stomach and the dusting of hair along his chest. He lifted weak fingers to his lips, dry and frowning, and winced as he reached his cheeks.

He dedicated an hour to the effort of rising from the stone cellar floor and removing the iron restraints that kept him bound during the long night. Another twenty minutes went to the aching, slow ascent to the main floor of the worn-down cottage that had been his home for the past four months. He'd recovered enough to fully bend his knees by the time he reached the tiny bathroom and its silently disapproving mirror.

The mirror wordlessly hissed its dissatisfaction with his reflection which now displayed three new wounds along his cheek. The marks stung at the touch, the skin red and blistered. He'd have to think of some sort of explanation for the scratches by Thursday morning, his next scheduled shift at the sundries store.

He'd just reached for the shower when a faint knock interrupted. Remus paused as a second and then third followed, the sounds stronger than the first attempt. After a few seconds of silence, the knocking began again. In no shape to face a visitor, he shuffled carefully back to the main room.

The knocking persisted, and he finally gave in, wrapping his torn cloak over his shoulders and palming his wand. He meant the door to only open the small space for a quick sending off, but the change had left him weak and slow. The unknown woman had his wand in her hand, and her foot through his doorway within seconds.

A binding hex trapped him to the floor, and Remus stared up at his assailant in complete surprise.

She stood unsteadily above him, her eyes unfocused and her wand hand trembling from effort. A darkly stained bandage did little to stem the regular drip of what he immediately recognized as blood from her wrist.

"Who are you?" he asked, an inexplicable concern filling him for the young stranger.

Her lips twitched briefly, something of a smile flittering for a moment. Her eyes met his and tears filled them as she spent several long seconds tracing over his features. 'I missed you, Remus Lupin," she whispered hoarsely.

He frowned, bemused; he had absolutely no memory of this strange girl. "How do you know my name?"

"Remus John Lupin, son to Lyall and Hope Lupin. Bitten at the age of four, you've just finished dealing with a full moon. You've a weakness for chocolate, are terrible at Gobstones, and hate your Patronus. You've been in semi-hiding since Voldemort killed your best friend and his wife, and you think your other best friend the man who betrayed them both."

His confusion grew with her every word, a slow fear growing behind them. Who was this girl- and how could she possibly know so much about him? "Who are you?" he repeated, his voice stronger now.

She wobbled as she lowered to his side; he felt a flicker of control return to his hands. "I've come very far, but I can't do this on my own. I'll need your help."

She tipped forward, careening into his still-bound body and dropping the wands in her fall. The spell broke, and Remus reached to catch her. He searched her face, dirtied and pale, and saw nothing there to explain her familiarity or words.

With her eyes barely held open and her fingers trembling, she clutched at his cloak. "Please, professor, we have to save them. Harry will die-"

"Harry? Harry Potter?" Remus leaned forward, drawing her closer. Her trembling increased, and a thin sheen of sweat stretched across her forehead. She needed healing, but first- he had to hear. "Tell me- what's this about Harry?"

Her lips barely moved and her breath grew heavy. "- the horcuxes. Sirius-"

She fainted, completely worn, and Remus spent far too long staring down at her still form, shock rendering him immobile. His own fatigue returned, and he felt a deep stirring- a heavy rippling- strum through him. Something inexplicable had shifted with her words, and he felt the world move it.

The uncontrollable had been changed, and this unknown girl had done it.

The Sacrifice

Prologue

Entanglement

A/N: I only realized in writing Entanglement that I had completely adopted the movie-canon scar as full canon; I suppose if I'm writing an AU, it's okay to play fast and loose with the two 'verses.