Disclaimer: I don't own Trials of Apollo.

HADES X
An Unexpected and Unwelcome Encounter

There was no difference between this side of the Cocytus to the other. Hades knew he had continued travelling in the correct direction because the fiery brightness of the Phlegethon had now gone even from his periphery, left far behind him much like the nephew he was supposed to have been travelling with, until Apollo decided to run after another of his considerable army of children instead of focusing on their objection, but the landscape looked much the same.

He continued shedding droplets of the Cocytus from his form as he traipsed across Tartarus, fuming that he'd been caught so easily, almost as easily as the previous time despite being certain his guard had been up against the river's tricks. It did not, he was uncomfortably aware, bode well for the next rivers; as he recalled, the rivers had tended to get more dangerous, the further into the Pit – the further away from the Underworld – he and his brothers had travelled.

Somewhere ahead of him was the Lethe, powerful enough to wash away the memories of even a titan – a discovery which had inadvertently put him in his current situation. Had Iapetus never fallen into the Lethe and had his memories wiped, he would never have somehow befriended Nico, and Hades' son would never have considered jumping into the Pit to save him.

With Poseidon in their midst, it had been far easier to ensure none of the liquid had dripped onto them, just in case, and back then they hadn't even known for certain that the Lethe could affect a god. True, titans were not gods, gods were technically more powerful, but if it could wipe Iapetus' memories, then Hades did not trust that down in Tartarus, it could not wipe his.

However, before he had that hurdle to overcome, there was another river to cross.

He was fully dry long before the next one came into sight, a handful of foolish monsters erased from existence when they got close enough for his blade to lash out and eliminate them – nothing of any power had challenged him yet, which was a relief but also a concern, because if they were not here then they were elsewhere, likely closer to the prison.

Or harassing Apollo, part of his mind pointed out.

He ignored it.

It was possible, he reminded himself, that he could get in and out of Tartarus with nothing worse than the rivers to face, except he knew that was a lie – even if Iapetus was firstly still intact and secondly willing to go with them, there was the matter of the voice summoning his son, and Hades' suspicions regarding that voice's identity had not been swayed yet. Bringing Iapetus back to the Underworld, to reassure his son that the titan was safe and not the owner of the voice, would not be good enough – Nico was too kind-hearted to trust that there wasn't, somehow, someone still in need of help. Nor had Hades earned enough of his son's goodwill that Nico would believe him if he said otherwise in the first place.

The voice needed to be silenced, proven to be a trap with no real victim, and Hades knew no-one else was going to do it.

Not with Apollo gallivanting off on some completely different and unnecessary mission that was doomed to end in failure. There was no way that Asclepius could leave Tartarus – Zeus would send him straight back down, and spit in Apollo's face in the process.

The younger god was wasting his time.

On the horizon, a glimmer of water – dark, dark water – became visible, the river rushing fast and furiously through steeply carved gorges in the membrane of Tartarus, rough with rapids in a way it didn't quite have up above, in the Underworld, but that suited its nature particularly well.

Hades slowed on approach, considering how best to tackle this particular crossing. Of all the Underworld rivers, this was the one he had the most to do with, an almost professional working relationship with, and while he was the stronger of the gods – at least, within his own domain, down in Tartarus was another consideration entirely – this was not one he cared to anger unnecessarily. If he did so, he ran the risk of losing one of the more powerful guardians of his domain, and Charon would be insufferable, because no matter how much the money-loving boatman grumbled about his job and pay, Hades knew that the part of the job he enjoyed was ferrying the souls across themselves.

Reaching the bank of the river, or more accurately, the lip of the gorge through which it ran, he halted in surprise. Floating on the inky-black surface, idly fidgeting with some of the clouds of pollution that streaked through the water, was a woman.

Neither Cocytus nor Phlegethon had bothered to show him a physical embodiment of themselves, content to remain purely in river form, but it appeared that Styx had other plans. The goddess was as beautiful as always, with her shifting colours – always dark, the colour of a starless night, of ink, of a deep purple that echoed in the blade Hades carried – and her pitch black eyes bored straight through his essence, seeing past his physical form and into who he was, himself.

The gods had given this particular daughter of Oceanus a great deal of power over them when they had chosen her as the keeper of their oaths. Before her, Hades felt stripped bare, exposed, in a way that very few beings could elicit.

He was, however, likely the god most used to the sensation; while Styx did not appear to him often, she was the boundary to his domain, the first or last guardian, and her appearances in the Underworld were not zero.

"Hades," she said, not bothering to straighten from her recline along the surface of her river, except along was not correct, because she was part of it, water rushing into her form and then out of it again with the fury that betrayed it as the river of hatred. For a lesser being, the sight might have been considered dizzying.

Hades met her eyes without hesitation. "Styx," he replied. Neither of them used honorifics with the other – they never had done, Styx older than he, but Hades in technicality her master, at least in the Underworld.

In Tartarus, the dynamic was not the same, was shifted slightly to the left, and Hades did not know where, exactly, they stood, but he knew he had no authority over her. Not here.

"This is an unexpected encounter," he continued. Neither of them made a move to get on the other's level – Styx remained as one with her river, and Hades remained separate on the bank. "You did not show yourself the last time I was here."

"I did not concern myself with you and your brothers back then," Styx commented. A hand more viscous than solid brushed a waterfall of hair back from her face carelessly. "You had not begun to use me as your oath keeper, so you were insignificant and beneath my notice." She chuckled, a discordant sound with the grating undertone of pebbles grinding pebbles beneath the melody of water over stones. "Do you regret forcing yourselves into my awareness?"

Hades didn't blink. "I am not my brothers' spokesperson," he said plainly. "Do not ask me what inane thoughts pass through their ridiculous minds. I have not understood either of them in millennia."

Styx drifted a little closer to him; her eyes had yet to blink.

"You're avoiding the question," she noted, and Hades narrowed his eyes at her for her impudence, but knew it would be foolish not to humour her.

"We have not had any serious disagreements," he acknowledged, and she rewarded him with a smile. It was beautiful the same way it was horrific, a maw of darkness and broken promises rimmed with sharp teeth waiting to close on the souls of those foolish enough to try and enter her waters uninvited – and even the invited were not safe.

"Oath Keeper," Styx agreed. "You alone of the gods have always kept your word. More than that," she continued, "you have more than once been the instrument of my retribution." A musing hum that sounded more like a grating saw than music rustled along the water. "Until you stopped."

Hades regarded her warily, unsure where she was taking the conversation but aware he would not be able to cross until she was satisfied.

"Zeus breaks promises as though they were never made," she said, as though Hades wasn't well aware that Thalia was not the first child of Zeus to be born after the Oath was made. Zeus had barely been able to restrain himself for a year before he was spreading his seed again – Hades had hunted down each child in betrayed anger as soon as he became aware of their existence, and Thalia had simply been his first failure, the first one to make it to Camp Half-Blood.

Of course Styx was the reason he had always, somehow, found out about the children, early enough to destroy before they knew how to fight back. He had never thought to question it at the time, but it made a large amount of sense.

"His son is much the same," Styx continued, and Hades frowned. He had many nephews thanks to his youngest brother, some mortal, many not. "Promises made with little thought, forgetting that to break them is to invite consequences." Her sharp, jagged teeth came together in a snarl. "The fool thought that I would kill him, unfurl his fingers from where they clung so desperately to the edge of Tartarus as he dangled over Chaos."

She scoffed, but Hades barely noticed, because suddenly the near-infinite seeming pool of nebulous nephews across the millennia had condensed down to a single possibility, a god who had been to the edge of Chaos and lived to tell the tale – barely, if Styx was to be believed.

Styx was the embodiment of hatred, not lies.

Hades did not like how uncomfortable he felt at the realisation that Apollo had almost, almost, been unmade.

"Why didn't you?" he asked, wondering what oaths Apollo had made and broken – the younger god played the fool, but he was not one and Hades had never known him to go so far with his façade that he would intentionally bring the wrath of Styx's vengeance upon him.

Styx scoffed again.

"Because I know you gods," she said, black eyes once again piercing uncomfortably through Hades and staring straight into his essence. "I know how to take you apart, piece by piece. How else can I select the punishment that will hurt the most when one of you invariably breaks the oath and has to pay?" Her mouth twisted into a snarl that looked half furious, half amused. "I know, Hades. I know who you love, how you love, why you love. Should you ever break an oath, rest assured that you will regret it." She shifted in the current again, disappearing almost entirely before remerging, closer to the bank where Hades stood. "Erasing Apollo's existence would not have resolved anything. It would have been a mercy, right then, to let him go rather than force him to keep fighting, keep suffering."

Hades struggled to believe that – a god's existence was precious. He remembered Hera's wails as she dangled over Chaos in a gilded cage, punishment for defying Zeus. They had reached up to the Underworld – she had never been the quiet sister – and echoed through his palace near-constantly. The edge of Chaos had been one of the few places he and his brothers had not dared tread during their inspection of Tartarus, the mere thought of being unravelled back into nothing enough to strike terror into all of them.

That the fall would not have been enough to destroy Apollo, would not have made him suffer enough to satisfy Styx… what would have done?

The goddess fell silent, watching him with her piercing eyes, as Hades grasped at straws, trying to decipher her meaning. He knew the answer, part of him whispered, but no matter how frantically he tried to find it, tried to pick apart what he knew of his nephew to find what would hurt him more than Chaos, no answer came.

After an eternity, Styx turned away from him and began to dissolve back into the water again. "It's a pity the two of you came down here," she said, almost idly, but the goddess of hatred did not do idle. "I was looking forwards to tearing the boy apart." Realisation struck Hades rather like one of his brother's blasted thunderbolts. "But we make a good team," she continued, body no longer separable from the water that made her. "I got another one instead, thanks to you."

Her form dissipated, leaving nothing but the furious river lashing past him, and Hades stared into the inky, swirling depths in something rather akin to horror.

And fury.

It throbbed through him, a rage sinking into his essence because he had been used.

Styx was one thing – his brother's broken oath had infuriated him regardless, so he had no qualms about eliminating the children that should never have been born in the first place. As the boundary of his domain, it was equally no hardship if he kept her happy on occasion by assisting in her punishments, although he would've liked to have been aware that she was using him to do so. He was confident he would not have minded in the slightest when it came to Zeus' illicit children.

But, despite her words, Styx had not instigated Apollo's punishment. She had taken an opportunity, but she had not created it – that dubious honour fell to one person Hades refused to obey like a mindless puppet, and the fact that Zeus had managed to twist his own fury into something that furthered his own agenda had his essence roiling.

Apollo had said it himself – why had he not been punished for the use of the Physician's Cure, if he had been the one to authorise it, and Hades had always known that he had been involved thanks to the blasted daisy ingredient. Hades had glossed over that, considering his nephew's mortal tenure punishment enough for that (something he was at least deserving of being punished for, unlike most of the paranoid reasons Zeus had bluffed his way through), and focused his ire on the one who had made it.

His nephew had always been closer to his children than most of the gods. Soft in the way most gods could never allow themselves to be, unafraid of falling in love over and over again, no matter how many tragedies trailed in his wake (and there were a lot of those – Hades had many, many tragedies of Apollo in his domain). It still felt strange, alien, even, that there was something that could hurt a god more than his own destruction, but if there was a god for which that held true, of course it would be Apollo.

Zeus, damn his brother, knew that. He had not agreed to Hades' demands to punish Asclepius for Hades' sake, but as a way to control Apollo further. Even the first time, Hades could see now, had been a carrot and stick situation – kill Apollo's son but then revive him, ensuring Apollo's loyalty whilst pretending to appease Hades' rage.

This second occasion, casting a god down into Tartarus for eternity? While Hades still liked it, delighted, even, in the idea that the irritating god would not trifle with death ever again, there was a sour taste to the punishment now, because it had not been a punishment for Asclepius at all, not in the mind of his brother. Zeus had taken Hades' rage and used it as justification not to punish the young god's transgression, but to hurt his own son further.

Had Apollo been on Olympus when news of his son's fate reached his ears, Hades wondered how he would have reacted, if it would have been extreme enough that Zeus would have called it unacceptable and declared that he once again had no choice but to teach his son a lesson?

He stared into the swirls of the River Styx, clouded with the pollution of broken promises, and wondered why Styx had given him this information. What she gained from it.

He didn't know, but he knew one thing – Asclepius' punishment could not be nullified, his own pride and fury would not allow it, but he would not let it be Apollo's punishment before the real perpetrator's.

His feet had turned him around, his back to the Styx and the disconcerting distant bubble of harsh noise that might almost be the goddess laughing, before he'd realised what they were doing, and Hades wondered why they had. The prison was the other way, across the river, and another river besides. His whole reason for being in Tartarus in the first place was now behind him.

Except that wasn't quite true; he'd entered Tartarus not just to find and stop the voice baiting his son, but also because he'd known Apollo would struggle so far from the Overworld, from light and life and healing and all those other things his nephew thrived on.

The nephew he'd let storm away from him, to save a son because apparently Apollo placed his sons above himself (and that, too, should have been obvious – why else had Apollo elected to claim the sunshine of the prophecy for himself, rather than let William stumble through hell?).

Hades let out a bark of frustration – even when he wasn't in his vicinity, Apollo apparently was still capable of being annoying, distracting, and the centre of attention – and stormed back the way he came.

Still steaming from Zeus' manipulation, from the way he was suddenly aware he was not as in control as he thought he was, from Apollo's kind-hearted idiocy – and really, what had his nephew done to get on Styx' bad side; Apollo was supposed to be smarter than that, the imbecile – he barely noticed Cocytus' attempts to drown him in despair, or Phlegethon's attempts to sear his form to pieces. He certainly did not notice how long it might have taken him to retrace his steps, nor care, for the first time since arriving in the Pit.

What he did notice was, homing in on a sudden beacon of light that flickered and wavered at the edges as though darkness was trying to snuff it out and was not entirely failing, was two gods covered liberally in ichor, surrounded by a hoard of monsters that Apollo should have been able to obliterate in seconds but was apparently struggling against.

His nephew was in a state – ichor stained his armour and his bare skin where it peaked out behind the protection. His throat was deformed, almost as though something had tried to eat him. (Hades had once been eaten alive, but that had been swallowed whole and infinitely bad enough. To be torn apart by teeth – what sort of hell would that have been? Although maybe that would have stopped him from being aware the whole time, from living and growing in a stomach with four siblings when there wasn't even space for one-)

Hades steadfastly refused to look at the other god, one he still hated, still wanted to see punished for what he'd done, for his disrespect of the natural order of things, of Hades' domain.

Uninjured, apparently unlike his mess of a nephew, he made short work of the remaining assailants, and stepped forwards, towards Apollo.

He barely got his sword up in time to block the arrow.

"Don't even try, Hades," Apollo snarled, but his quiver was empty and it took him more than a split second to materialise another arrow in his hand. Hades was the stronger of the two anyway, although perhaps not by so much as he had once assumed; not that that mattered then. In Apollo's current state, there was no way the younger god could hope to defeat him in a fight.

"Are you so weak you cannot even drive off a simple hoard of lowlifes?" he replied, although he stayed where he was – just because he could deflect Apollo's arrows in the archer's current state did not mean he wanted to. "Where is my thanks for saving your hides?"

The new arrow was drawn back, and Hades rolled his eyes. "Put that down," he ordered. "If I intended on harming your son at this time, I would not have gone through the effort of saving him first."

Apollo's eyes, still Phlegethon-orange, bored into him not too dissimilarly to the way Styx's had, and Hades recalled that one of his nephew's many domains was truth. He did not know exactly how that manifested, especially between gods, but after a moment, the bow was hesitantly lowered.

"You came back," Apollo said, his voice low and rough. Hades was certain that his journey through Tartarus had not been as uneventful as Hades' own, and wondered which of the Pit's more powerful inhabitants he had fallen foul of – and no doubt defeated, to still be standing, and with his son, who would have been torn apart long before Apollo himself. The near-rasp of the god of music's voice did nothing but further cement that certainty. "Why?"

Why, indeed.

Styx being all nice and rescuing Apollo and never actually addressing the broken oaths from THO is one part of TOA that never sat right with me. Ergo, this happened.

Thanks for reading!
Tsari