A/N: I originally didn't intend on writing this, funnily enough. I had planned to write some Aether harem stuff, but no immediate plans - but this one just kind of came to me as I sat listening to music and it all flowed from there. As of writing this I've got chapters 1-3 finished, with Ch4 underway, so they'll come within the month.

This will also be an Aether x Harem fic. Spent quite some time digging for such content, but alas only found a handful of stories that scratched the itch. Thus, taking it upon myself to whittle out a few fics of this nature. Got some other, less-plotty stuff in mind for future fics, but this one will probably be more a plotty harem style fic.

That aside, do enjoy~

Struck Down

Chapter 1: Icarus

Dragonspine was a cold, cold place.

Probably the understatement of the century, admittedly. It was well-known to a deathtrap for foolish adventurers and while there was plenty of research opportunities to be had, that was only if you could survive long enough to undertake said research. Combine the lethal cold with the Hilichurls and other monsters that resided on the mountain and you had a recipe for one of the most treacherous parts of Teyvat this half of the continent.

Normally, Aether wouldn't be there, much less visit it of his own volition. He'd come through long ago and cleared it out of any chests, slayed the most problematic of Hilichurls and helped local researchers with their studies – but right now, if he was being honest, the cold was what he needed. He needed that frigid, biting cold that distracted him from his own thoughts, the peril that forced him to be self-aware of his surroundings, that risk of death to make him feel alive.

All because of one tiny problem.

Lumine.

He'd arrived in Mondstadt and helped them. He went to Liyue and solved their crisis. He ventured to Inazuma and resolved their civil war. Traversed the Sumeru desert and restored Nahida's authority, and most recently went to Fontaine and uncovered a century-spanning conspiracy that ultimately saved the Hydro nation. Yet despite it all, he still had not gotten Lumine back. He had gotten hints at first, his worries had gnawed at him, but it wasn't until he saw her in Abyssal regalia that he truly knew she had been taken by the other side.

How was he supposed to respond to seeing such a thing? Part of him argued he should save her – and he would – but how? The Abyss was enigmatic at the best of times and corruptive with its mere presence. How did he save his dearest sister, who had presumably been lost to the Abyss for decades if not centuries by this point? He had seen the look in her eyes; she wasn't just a puppet, not wholly. She believed what she said when she stood on the side of the Abyss.

Had it told her lies, he sometimes wondered? Or perhaps was the Abyss telling the truth, and he was on the wrong side of things?

A cold wind helped banish such thoughts, but not entirely – never entirely. He refused to believe he was on the wrong side; the people of Teyvat had their problems, yes, but many were on the road to mending those problems. Venti was proud of his people for being independent as was Zhongli, both enjoying their retirement after growing their nations to such glory, whilst Raiden Shogun had been put in her place and shown the errors of her Vision Hunt and all the other issues that involved. Nahida had been freed and was now able to govern Sumeru to a more prosperous future whilst Fontaine had been saved from a century-coming prophecy – the world was improving. Slowly, yes, but these things never happened overnight.

But in his darkest moments, he wondered what would happen if he just... joined Lumine. Surely he should be allowed to, right? He vividly recalled her 'destiny' – her desire to swallow the thrones of Celestia. He couldn't fault her for that, really; hell Celestia was the only reason the two of them were on this planet in the first place. All because they ventured too close and were attacked by the Unknown God.

Just thinking of the woman made his blood boil. The cold winds did little to help this time; her cold visage reigniting the flames of anger in his heart. It was all her fault. If it wasn't for her, they wouldn't be stuck on this world. If it wasn't for her, Lumine wouldn't have fallen into the Abyss. If it wasn't for her, everything would be right with the world, he was sure.

But if it wasn't for her, you would have never met everyone. A tiny voice in his mind reminded – flashes of his comrades coming to mind. Amber. Keqing. Ayaka. Collei. Furina. So many good people who had brightened his whole life, who he would have never met had the circumstances been different. Had he awoken at another point in time, he'd had never run into them. Had he woken a decade later they would've been older and wiser, or if he had been a decade sooner they would be mere children, seeing him as more a big brother than an ally, a comrade, a friend.

Yet the thought of his friends dimmed his anger only briefly.

Was he wrong to feel like this, he wondered? Every setback, every failure, he swallowed them all with a smile and continued to march forth for the people behind him – but after the last few months, how could he go on any further? He still had two whole nations to explore and befriend before he had any hope of meeting Lumine again. But did meeting her even matter if it just meant he would see her corrupted by the Abyss, her smile so cold and eyes filled with such cruel determination – a determination to make Celestia pay for what they had done to the world?

And when the time came, could he raise his sword against his own sister?

Aether shuddered, and not from the cold. His fingers scraped through the snow and found purchase on a stone, helping haul him up onto flat ground as he reached the summit of Dragonspine. His feet cut through the snow and he ascended onto the old stone platform before the up-draft that could carry him to the very highest point atop the pillar – but in truth his eyes were looking past the pillar, towards the distance island floating high in the sky, so oblivious to the toilings of the mortal world.

Celestia. The world where the Unknown God resided.

A cold wind blew past him, his arms numbing from the eternal chill, but it didn't quell the burn within him. Anger had come and gone the last hour but it burned hotter than ever as he stared at the little island in the sky, wondering how many people they had seen suffer, how many injustices had been committed with their ignorance – how many others like his sister had been lost to the Abyss or killed by its minions, all because they were too high and mighty to care about what went on?

Aether put his right foot forth, eyes narrowed as he extended his hand – sparks generating between his fingertips. Not a second later they flashed into being, lightning concentrating into the form of an arc and becoming a bow, complete with a razor-thin bowstring. Many hours had been spent training his Electro vision to create a physical weapon – one he held with pursed lips, enduring the heat the living lightning created against the cold skin of his palm.

Hesitation arose within him, realising pointing a bow at Celestia was perhaps not a wise idea... but they didn't care, did they? They didn't care for the pleas of the people. They didn't care for the suffering of the fallen. They didn't care for him or his beloved sister – and so with a snarl Aether drew back an Electro arrow, aimed-!

And fired it, sending it careening off the edge of the mountain.

'Of course.' Celestia was too far away to be shot down so easily – had it been and it would've happened centuries ago, he was sure.

But it gave him catharsis. A meagre, spiteful revenge against the ones who wronged him.

So despite the pain it caused him he crafted another Electro arrow, the spectral bolt sparking and stinging his flesh even as he notched it, the thin string pulled back further and further, the lightning bending with it – and then off it went, soaring faster than before and reaching farther. But still falling far too short of shooting down Celestia.

Was this symbolic, he wondered? Reflective of the fact he could never harm Celestia, that he couldn't slay them had he the chance? Flashes of his battle with the Unknown God reminded him most vividly of that – of soaring through the sky with Lumine by his side, of clashing with the white-haired goddess, only to be pushed back effortlessly and ultimately sealed away, not even landing a blow against her.

He gripped his bow tight, enough that the construct sparked and warped; at risk of collapsing from his strength. Aether didn't relent in his grip though, eyes only on Celestia, remembering those golden eyes so vividly. So cold, so uncaring, yet so cruel in their judgement. His fingers clutched at the false feather of an arrow and he aimed it, pulling the string back. He held it, unconsciously channelling more Electro into it, his lips pulling back into a snarl even a wolf would envy.

Rational thought was absent, the cries to stop ignored as he channelled his foreign powers. Rage shook his bones, fury drew his muscles taut, anger bared his teeth and hatred made him scream-!

And then the arrow flew, a sonic boom clapping his ears.

A line of vivid purple soared through the skies of Mondstadt and over Liyue, a distant speck in seconds. Straight and unarching it gradually grew dimmer as the distance grew, becoming a faint blur then disappearing altogether.

Until a purple explosion illuminated the side of Celestia.

Aether felt the rage drain out of his system along with the blood in his face, a shiver rattling up his spine. 'It... it hit?'

Sure, he had aimed for Celestia, but he hadn't actually expected to hit it.

The distant explosion steadily withered out, what looked like smoke and debris falling from the heavenly isle; some of it disintegrating and other parts falling far below into the unpopulated wilderness of Liyue. However that didn't dispel the sudden wrongness that pervaded his being, aware that he had done something maybe he shouldn't have – and perhaps, shouldn't stick around to-

Warning bells screamed in his mind and Aether ducked, his palms catching himself as he rolled – and the dull thunk of metal on stone made his head turn. A sword grazed over the snow, thick like a greatsword but single-edged and built of a pristine ivory with gold intricacies. The greatsword length drew his eyes up to the simple guard, and then to the hand holding it. One hauntingly familiar, luring his gaze up further – to the woman holding the weapon.

''You...'' Aether breathed.

The Sustainer of Heavenly Principles.

The Unknown God.

Aether didn't get the chance to even speak before she moved; her sword rising in what felt like a heartbeat before coming down – and a sharp clang echoed as he blocked it with a sword of his own, manifested just in time to stop it. The startling strength of the goddess though forced him down onto one knee, his grunt going unheeded as she pressure down further, his blade rattling in his grasp as he tried and failed to push back against her.

She relented briefly – and Aether took the chance, yelling as he pushed her back. It gave him the room to stand but she was on him a heartbeat later, greatsword coming at him from the side. He blocked it but the impact jarred his bones, his boots crunching the snow underfoot as he was pushed back slightly. She didn't press further, simply pushing on her blade as she examined him with those soul-piercing eyes, so detached yet so oddly focused on him.

Then she retreated, and her sword came down from above. He parried this time, knocking it aside and leaving her open – but his thrust in turn was parried as she pulled her sword back, the very tip of it cutting his cheek as it passed before slashed diagonally, forcing him back lest he be bisected. The way she wielded the heavy thing with just one hand spoke to her strength, and as a response Aether swapped out his sword for two – the Primordial Jade Cutter, and the Skyward Blade. Two of his best.

Because he had a feeling nothing less than best would be able to harm a goddess.

''Funny. I allowed you to live so many centuries ago, yet now you dare strike at Celestia.'' The Unknown God spoke, her drawl disdainful. ''Perhaps I should simply finish you off and forsake destiny.''

Aether gripped his blades tight. ''What do you mean?''

''It does not concern you.''

He felt a flash of irritation, his prior anger resurfacing. ''It doesn't concern me...? You were the one who trapped Lumine and I on this world! If it wasn't for you, we'd be off adventuring through the stars – you are the reason we're standing here right now! Of course it concerns me!''

''Do not use that tone with me, human.'' The derision lacing her tone made him growl. ''You do not get to decide-''

He had heard enough. Rage compelled him forth and he leaned into the emotion wholeheartedly, the distance closed – until with a resounding clang his two swords clashed against her guarding one. Despite the speed of his approach the Unknown God looked entirely unsurprised, her expression neutral even as their weapons rattled together in a momentary contest of strength. One that ceased as she pushed back, his momentum inverted as she nearly sent him flying over the edge.

A burst of Anemo stopped that and a second kicked him into the air over her – a furious yell escaping Aether as he descended upon the goddess. She blocked his blade but he didn't cease, his momentum transferring as he flipped over her and landed right behind her. A backstab was parried by the flat edge of her sword and he leapt back to avoid the sweeping slash that followed, the sheer strength she commanded enough to create a gust of wind that buffeted against him.

''Cease-''

Aether didn't. Anemo kicked him forth with greater speed and he rushed her – only to feint, passing her by. A Geo construct emerged from the brickwork and he kicked off of it, ignoring the strain in his muscles as he launched back at her. His Jade Cutter clashed with her greatsword while his Skyward Blade swung for her face, missing only by inches as she leaned back, eyes narrowing in irritation at his affront.

He leapt back but this time she went on the offensive, her speed taking him off-guard. Her greatsword came thundering down and he didn't even try to block it, side-stepping the attack instead. For a brief second, their eyes met.

And then he lunged. The Unknown God pulled her sword back in time to block but he made her stagger – and he capitalised on that, empowering himself with Anemo as he unleashed a flurry of attacks one after the other, the resounding clangs of steel echoing across the mountaintop as he didn't give her a chance to counter-attack. Gusts of wind sharp as steel blew too, cutting across her exposed arms and drawing golden blood, the ichor dripping down her flesh.

Her snarl was his only warning before she forced him back, her swing nearly sending him soaring over the edge of the cliff had he not deployed his glider, giving him the second needed to blast Anemo under him and launch him back onto solid ground. His feet had graced it for no more than a moment before he found himself leaving it – leaping up to avoid the sweeping cut from the Unknown God, her blade obliterating the stone brickwork it came into contact with.

Twisting mid-flight Aether drew Electro into his Jade Cutter and brought it down, a slash unleashing a shrieking arc of thunder. It was back-handed aside, the bolt crashing into the snow harmlessly, and as gravity pulled them down his Skyward Blade met her unnamed greatsword. Their difference in strength made itself abundantly clear as she launched him back, his boots hissing through the snow as he forced himself to come to a stop.

'She's not using those cubes.' Aether noted abruptly, like a shock of clarity had hit him.

And with it, a thought.

'Is she not taking me seriously?'

His fingers coiled, the handles of his swords groaning in protest – and with a snarl Aether rushed her. Electro crackled along his Jade Cutter and Anemo ensnared his Skyward Blade, the aeolian noises intermixing with the shrieks of thunder. Both of which came together as he brought his blades together in a cross-guard and swung them, Anemo and Electro combining to form a swirling maelstrom that tore up the snow between him and the goddess.

Only for it to be split in two with a single swing, her glowering visage glaring ahead – at nothing. A glint was her only warning before Aether emerged from the left side, Electro blade swinging up-

-and carving a deep gash across her side.

Golden blood flew in slow motion, lit by the unclouded sunlight that fell upon them. A light that reflected upon Aether's toothy, borderline savage grin of satisfaction.

Rage morphed her visage into a fearsome one. ''You dare-!''

Razor winds cut into her flesh and forced the Unknown God back. Aether was just a step behind, Anemo swirling around his Skyward Blade and unleashed with an upwards swing – a billowing crescent dispelled by her backhand while her greatsword blocked his Electro-wreathed blade. The lightning tried in vain to channel across her sword but was rebuffed; whatever material it was constructed of non-conductive, or at least rebuffing the element.

It didn't stop Aether from stomping his foot, a Geo construct knocking him into the air. Thinking fast he summoned another in the air itself and kicked it like an oversized football, sending it rocketing down at the goddess like a meteor. Her fist stopped it, the whole construct quaking with the impact before imploding into thousands of pieces. Pieces that had barely landed when Aether came crashing down like the Shogun herself, his Jade Cutter wreathed in Electro and causing a miniature lightning strike.

The Unknown God endured it with a snarl, her blade grinding against his as she swung and forced him back. She was on him in a heartbeat, a flurry of slashes forcing him on the defensive – her strength too great to block and forcing him to constantly side-step and parry lest he be sent flying off the edge of Dragonspine. His mind raced but he couldn't get the chance to summon a construct – all he could do was empower his blades and endure her onslaught.

His patience was rewarded as she raised her greatsword high. He blocked it with his Skyward Blade before it could gain too much momentum and she caught his Jade Cutter, both of them seemingly deadlocked.

Allowing Aether to slam his forehead into her nose.

The Unknown God staggered back, startled, and he acted upon her weakness. Electro and Anemo swirled and he yelled as he brought both enchanted swords down, unleashing the twin elements in a maelstrom across her torso. Cloth ripped and golden blood lit the maelstrom a malevolent hue of purple, green and gold, churning and tumbling – until the combination exploded with great force, sending Aether tumbling head over heels to the very edge.

Coughing the smoke out of his lungs Aether stumbled to his feet, glaring in the direction the Unknown God had been. The smoke thinned quickly to reveal she was still standing, but she had not come out unscathed. The front of her dress was scorched apart or torn in places, revealing the bare flesh underneath coated gold by her divine blood. It dripped off of her form and made the snow melt from its heat, her fingers running through the rivulets on her stomach and lifting it to her gaze.

Her teeth clenched; grinding, gnashing. ''You insolent, ungrateful...!''

Aether scoffed, cutting her off. ''Ungrateful? For what? Being sealed away and having my sister taken away from me?!''

''Ingrate!'' The Unknown God barked, eyes ablaze. ''You and your equally foolish sister were about to step into the Cataclysm! Had it not been for me you would've perished among those in Khaenri'ah – or worse, plunged Teyvat into chaos with your mere presence!''

She lunged, her wounds not hindering her as she slammed her blade into his own. He grunted, wincing as he was forced back. ''H-How...?!''

''The Abyss.'' The low seethe to her tone surprised him.

A surprise she ruthlessly took advantage of, stomping on his foot and distracting him – and then her blade cut past his own, the sparks blinding him for a split-second and allowing her to cleave across his chest. He yelled in pain but she grabbed him by the throat, paying him back as her forehead crashed into his own temple, stunning him for a second and letting her throw him behind her; sending him tumbling across the ruined ground between them, coughing and groaning.

''Listen and listen well, boy. The more outworld knowledge you outlanders bring, the worse the Abyss will become as it tears apart the foundations of the world to remake it in its image.'' The Unknown God intoned sharply, a wince marring her visage as she touched her bleeding chest. ''Had it not been for the Divine Nails, the world would be uninhabitable by this point in time.''

''So you threw my sister to the Abyss?'' Aether growled.

The Unknown God looked aside. ''For the sake of Teyvat's future, I did indeed.''

The confession fed the tumultuous feelings inside of him, and his fury was mirrored in the Unknown God's eyes – her words resounding with the authority of a god. ''Know this, for you have proven yourself worthy of such knowledge. But such worth will not let you abscond from retribution.''

Lifting her greatsword the Unknown God said something in an unfamiliar language – and not a moment later six identical swords flashed into existence above her, three on each side of her original sword. They floated independently and with a swing of her sword she commanded the six clones into action – sending them soaring straight for him.

Cursing under his breath Aether leapt with a burst of Anemo but the swords followed, homing in on him. Thinking fast he made a Geo construct and kicked it towards one whilst dodging another, the blade whizzing past only to bleed off its momentum and spin around to face him. He didn't have time to worry about it though as another greatsword came rushing in, parried aside by his Jade Cutter while another was forced back by his Skyward Blade.

Gravity pulled him down, accelerated by Anemo to avoid the two going for his front and back. He touched down in a crouch but the Unknown God was already before him, her blade raised like an executioner's axe and bringing it down with similar force. It never reached his neck as both of his blades blocked it, but his tired arms quaked under the weight of it, pinning him down – and leaving him vulnerable to the incoming blades.

'Crap...!'

Thinking fast he inhaled a deep, Anemo-rich breath – and exhaled it out with force. The element responded to his will and forced him back, her blade cutting across his head but not splitting it open and instead doing that to the stone where he once stood – her six other swords impaling that same spot. He'd have been cut into pieces had that hit.

However she was open. He acted on that knowledge, Anemo kicking him forth. She raised her blade as expected but he let himself be launched over her, landing behind her and slamming his fist into the ground. A Geo construct erupted out of the ground under her and knocked her over, forcing her to stumble to her feet. He was in front of her in a heartbeat, Electro crackling along Jade Cutter and nearly severing her head from her shoulder.

CLANG-!

Had one of her swords not intercepted, sparks both metallic and electric flying from the collision. Aether swore and pulled back but she was faster, another of her swords flying into her free hand and allowing her to slash down his front. He staggered and raised his twin swords, mortal meeting divine-!

And divine won as his blades shattered.

Her two swords carved their path down his front, nearly severing his arms but slashing his pectorals instead. The pain knocked the air from his lungs and he stumbled back, falling to one knee. Blood running down his forehead forced his right eye to close and he couldn't bear to release the broken hilts of his swords, his grip on them ironclad.

The Unknown God walked up to him. Panting, dripping golden blood and with righteous anger in her eyes she glared down at him, standing slightly to the side as if prepared to be his executioner. He tried to stand, to fight... but his body was far past the point of its limit. He couldn't even feel his arms any longer, he dimly realised, and the amount of blood staining the snow under him was probably a lethal amount.

''You are strong.'' The Unknown God stated coldly. ''But not enough to change fate.''

''T-Then I'll...''

Her brow raised. ''Speak up.''

Aether obliged, raising his head despite his body's protests. ''Then I'll get stronger. Strong enough... to beatyou...andto shatter fate.''

''Bold words.'' Her eyes narrowed, all her swords floating above her.

Allowing him to count only six.

''Then know this, outlander.'' Her empty hand rested barely on his right shoulder.

In the distance, he spotted a glint.

''Know, that it was Asmoday who struck you down.''

And then not a second later her seventh sword shot from over the horizon, moving at a speed unparalleled – and pierced him straight through the heart.

The sheer momentum packed into the blade sent him flying backwards, the summit of Dragonspine vanishing in a second – the wind roaring in his ears as he plunged through the clouds, soared across the mid-afternoon sky-!

And then he hit solid earth, and knew darkness.

[END]

A/N: Baring in mind I don't know much of the lore post-Liyue at present, so if there's any lore inconsistencies, apologies~