The first time Achilles saw the prince, he was struck by how ordinary he looked. He only half-heard Master Hades’s instructions - that he would train this boy in martial pursuits, keep him disciplined in mind and body. Zagreus’s pose was easy and relaxed, feet apart, but he was standing in a way that just shielded him behind his father, and he cast his gaze anywhere else except at Achilles.
He didn’t have the faintest clue how to train a nascent god. There were no instructions or common wisdom for this kind of thing. Zagreus remained silent as they walked to the training room, and now they stood face to face. Achilles would have thought he was nervous, if it wasn’t for the dark and primordial power that he could practically feel emanating from him.
It was his task to hone this raw potential to a gleaming edge.
Zagreus was beginning to fidget under his appraisal. He supposed that he would try to mentor Zagreus like any other young warrior. It would do as a starting point. “What kind of weapons do you prefer, prince?” he asked.
“I’ve had training in the sword, bow, and spear.”
“You’re equally proficient in all of them?”
Zagreus’s shoulders tensed. “No, I... prefer the sword.”
Achilles nodded. Not his own area of expertise, but it was best to start on familiar ground.
He spent the first hour going over the basics- proper grip, stance, and balance. He didn’t know what, if anything, Zagreus’s previous mentors taught him, and it was best to catch mistakes before they set in. To his pleasant surprise, Zagreus had decent form, and only needed a few minor corrections.
Zagreus bore the lesson in near silence, with the occasional “Yes, sir” and “Okay, sir”. He must have found it boring, but that was fine. Achilles didn’t expect him to be enthused by the first lesson, and a prince like him wasn’t obliged to do more than tolerate his tutors.
When he was satisfied, he moved on to a series of basic sword drills. Zagreus imitated him through each step and swing.
“Is this familiar to you?” Achilles asked.
“Show me, then.” Achilles stepped back and let him have the floor.
Zagreus exhaled, and his training blade went into a blur. He strung together the movements as smoothly as a dancer, his sword flashed faster than ordinary eyes could follow. Achilles raised an eyebrow. He grabbed a training spear, and jabbed it towards Zagreus. He deflected it easily. Achilles felt the dark electricity surge through the point of contact, a split second before the spear shattered in his hand.
Zagreus stepped into a textbook defensive stance. His mismatched eyes watching back expectantly, his chest heaving.
Achilles couldn’t help but laugh, a sharp and brief exhale. Zagreus frowned at his reaction, so he at least attempted to bring himself under control by raising his hand to his mouth.
“Well, let’s... call it a day for now. Same time tomorrow,” he said, keeping his voice carefully light.
Zagreus ran off, seemingly relieved by the early dismissal. Achilles pushed his hand through his hair, and threw out a silent plea for help to Chiron, the mentor of his youth. He was going to have to rethink his approach.
Achilles wasn’t sure if Zagreus would even show up the next day, but the prince dragged his heels into the training room on time, and gave him a cautious nod by way of greeting.
He put Zagreus through a series of difficult spear drills. Finally given a proper challenge, his face was set in concentration. His spear whirled in the air, slashing through imaginary enemies.
Achilles stopped him. “It’s clear that you know a lot of techniques, prince. I want to see how well you can apply them. Spar with me, use any weapon you want.”
“All right,” Zagreus reached for the training sword.
Achilles shook his head. “Real weapons.”
Zagreus hesitated, then picked up another sword, a solid piece of gleaming obsidian from hilt to edge. “I can’t pull my blows with this.”
“No, prince. We’ll fight until one of us is vanquished.”
“Are you sure- “
“If you’re unwilling, we don’t have to fight, we’ll end this right now, but that’s my only condition when we train,” Achilles said. He was acutely aware that he was gambling his own employment on Zagreus’s reaction, but he had already hardened his resolve.
“But... why, sir?” It was the first time Zagreus asked him a question.
“Sparring with training weapons is just play-fighting, it's not the same. If you fight, you must learn to kill cleanly, with as little pain as possible. This is the most crucial lesson I’ll teach you.”
After a moment of hesitation, Zagreus nodded.
“No holds barred,” said Achilles, leveling his own spear at him.
Zagreus was standing in front of him one moment, and in a blur the next, a gouge left on the stone floor the only indication of his movement. Acting on pure reflex, Achilles raised his spear and caught the savage edge of his blade just inches from his face. Their weapons clashed again and again, with enough force that the air around them trembled. He let his instincts take over, speed and movement singing through his phantom limbs. Zagreus was keeping pace well, but he could sense him beginning to tire, moving more towards the defensive. He pressed a bit harder, scoping out weaknesses in his technique.
Zagreus grunted with effort as he barely parried a blow. Achilles was close enough to see his eyes go wide. If he saw genuine fear in them, he would have pulled back a little, but they held only focus and determination. And a sudden glint of cunning, the boy must have spotted an opportunity.
Sure enough, Zagreus surged forward and went for a fierce blow. He could have dodged to the side, but he blocked it head-on, letting himself absorb the force and fall back a step. The unexpected shift of balance made Zagreus stumble ever so slightly. He caught himself almost immediately, but that was enough of an opening for Achilles.
His spear drove clean through Zagreus’s chest, finding its mark. Zagreus only had time to let out a choked sound. His body dissolved in a shower of dark ichor before it even hit the ground.
Achilles breathed heavily. The spark of fear that had been jumping in his chest for the past day finally calmed a little. The flame in Zagreus could still be controlled. Not indefinitely, not even for long, but there was enough time to, hopefully, do his work.
He left his spear on the floor, headed to the Pool of Styx in the main hall, and waited. The surface bubbled and frothed, and a moment later Zagreus broke the surface, gasping for breath.
“Damn it. Sorry,” he wheezed between coughs.
“Don’t be, you did very well.” Achilles offered him a hand, smiling warmly at him.
Zagreus only stared at him for a moment, then he took his hand.
Once Achilles managed to break through his shell a little, Zagreus proved to be an eager learner, wanting to master every kind of weapon in Hades’s armoury.
He no longer held back in their sparring sessions. He could tell that Zagreus improved the most when they could throw everything they had at each other. Right now, he was on the aggressive, pressing him towards the edge of the courtyard with a relentless flurry of spear jabs. He varied his own techniques often, so that Zagreus wouldn’t become accustomed to fighting against his particular style.
Zagreus glanced to the side, another few steps backwards and he’d be forced off the ledge and fall into the void below. It didn’t look like there would be a way out, but then, without warning, he shoved his hand against Achilles’s chest and shouted a curse. Achilles felt the bolt of blood crawl through his form like freezing cold lightning. It fizzled away before spreading very far in him, but it still sent him reeling back momentarily. Zagreus looked equally surprised.
In the race to regain their composure, Achilles won by a second, and Zagreus’s body disintegrated into blood around his spear again.
Like every sparring session before, he returned to the pool to wait for Zagreus’s return. Dark red ichor trickled along the seams of the floor tiles, swirling and bubbling affectionately around his heels, as if it was consciously following his steps.
The ichor drained into the blood pool, and Zagreus emerged, splashing a few surprised shades. He was a dripping, undignified mess, sitting in knee-deep blood, but he was grinning from ear to ear. He looked up at Achilles, eyes shining.
“Did you see that? I- I’ve never done that before,” he said.
The incident did not go unnoticed by Master Hades, and later that day, Achilles was called to an audience before him.
Achilles dutifully reported the details of the training sessions. Hades listened in silence, the scratching of the scribe shade’s quill the only other sound accompanying Achilles’s voice. Hades said nothing for so long afterwards that Achilles dared to speak again: “Master, if the prince has committed some transgression, I will take full responsibility, begging my Lord’s judgement. I put him through these lessons-“
Hades halted him with one raised hand. Achilles lowered his head again.
He finally spoke. “Your method is unorthodox, but it appears to have some effect, where previous attempts have failed.”
Achilles remained silent.
“Perhaps I ought to observe his progress for myself,” Hades mused. “Scribe, do I have the time?”
“Your appointments are full for the next millennia, Master."
“A shame,” said Hades, in a tone devoid of interest. “You may go, shade. Continue what you are doing.”
With that, he was dismissed, but not given leave until a physician and three priests looked him over, and declared him suffering no lingering curses or ills.
Achilles remained troubled by the meeting the next day. Perhaps his lessons had been too harsh on Zagreus, but why his father showed no concern for him, he did not know. Or perhaps, a mere mortal like him could not truly understand the consequences of immortality, and he really was more out of his depth than he thought. He was prepared for the worst, but as he approached the training room, he heard Zagreus already there. First time he’s shown up early, he thought.
“Blood and darkness! Blood and darkness! Blood and- blood-”
“Say it like you mean it, boyo! Really reach deep inside, you gotta really want to curse me! Pretend I’m going to kick your dog!”
“Oh hey, your teacher’s here. Guess I’m off the clock!” The skeletal training dummy disappeared as soon as Achilles turned the corner. Leaving Zagreus standing there alone, looking a little awkward.
“Making progress?” Achilles asked.
“Well, I can do this now, but it’s not as strong as that first time.” Zagreus raised his hand, and after a few seconds of furrowing his brows and muttering under his breath, produced a small swirling vortex. He set his eyes on an archery target on the far end of the room, and hurled the bolt of blood towards it. It fizzled against the wood, barely leaving a scratch.
He looked back at Achilles. “I’ve never manifested any kind of power until now. Hypnos got his earlier than me, but he says he didn’t get his domain until much later, so I suppose I have time to work on it.” He scratched his head. “Erm, by the way, sorry I tried to place an ancient curse on you. I know that was irresponsible, and you don’t know what side effects messing with curses can have-”
“I’m all right, prince.”
“Did it hurt?” Zagreus asked, sounding much more genuine. “Skelly says it doesn’t, but he can’t really feel anything.”
“Not worse than any other weapon.” Achilles reassured him. “Come on, let’s get started on drills.”
“I don’t know how I’m ever going to defeat you,” Zagreus groaned, wringing blood out of his chiton.
They were walking out of the atrium together. Achilles usually had to return to his post after their lessons, and Zagreus took to accompanying him back, discussing technique and tactics on the way.
“I’m sure you will, one day,” Achilles said. “My abilities come from my lineage, but I was still only a demigod. Your ties to the source that powers us both is much stronger.”
“I just- I guess haven’t been giving it my best lately,” Zagreus said.
Truth be told, he could tell that Zagreus’s performance was at a low recently. He often showed up to lessons looking tired, and he saw him around the halls less often.
“Listen, Zagreus. If there’s something the matter, and I can make things easier for you, you should let me know,” he said seriously.
“Nothing’s wrong, sir. I’ve been busy with lessons, is all.”
“Music, composition, mathematics… governing."
Quite an eclectic array of subjects. “Your Lord Father is making you take these?” Achilles guessed.
“Yeah. I mean, I don’t know what my gift is, but it clearly isn’t poetry.” Zagreus waved his arm around. Then he added quickly: “But I like your lessons, and I don’t want to give up weapons training- it’s the only thing I’m good at.”
Achilles was seized with a familiar apprehension, like one of Zagreus’s cold bloodstones, twisting his insides. “Has your father ever said what your lessons are for?”
“He’s - I don’t know, he wants me to act more like a prince? He thinks I’m too idle, but at the same time he doesn’t trust me with any responsibilities. I bet he’s just trying to keep me busy. He's been piling all these lessons on me since the day I learned to cast blood.”
“He hasn’t talked about earning your domain?”
Zag looked puzzled by his questioning. “No, but... he wants me to stay in Tartarus, find my domain down here. Makes sense, I guess. I seem to be taking after Mother more in that aspect. Maybe I’ll accompany her some day.”
Achille’s heart would have jumped, if it was still beating. He felt something like a strange sense of relief, a weight lifting off him. But Zagreus was clearly in a glum mood, so he betrayed nothing of his feeling. Instead he tried to comfort him. “It’s fine to not take to all of your subjects as well as you’ve taken to combat.”
“Father hires only the greatest shades to have ever lived as my mentors. He says I should be more grateful,” Zagreus said quietly.
Of course, only the best for a prince. “Even so, it doesn’t mean you have to exceed every expectation set on you.”
They’ve been standing in the residence hall for a while now, where he took up his usual station. Still, Zagreus lingered by him, idly tapping his feet.
“Don't you have somewhere to be, Zagreus?”
“I hope you’re not dawdling for your next lesson.”
“Orpheus doesn’t care if I show up late,” Zagreus shrugged.
Achilles leaned against his spear. “You know, when I was alive, I played the lyre. I’ll surely never be as good as Orpheus, but that didn’t mean I couldn’t enjoy it for its own sake.”
“Seriously? No way.” Zagreus laughed.
“I am more than just the stories that remain of me.” Achilles said mirthfully.
“But your hands are too big for- er, um, I mean.” Zagreus stammered, embarrassed.
“Do you...” Zagreus started again, with a hopeful look, but he stopped short. “Never mind, I should go now. I’ll see you tomorrow, sir.”
Achilles watched him leave. He was faintly grateful that Zagreus didn’t ask him to play. That would be too close of a boundary to cross, and perhaps the prince had sensed it too, somehow.
Still, as he let the duty of standing guard distract himself from his thoughts, he could faintly hear the sound of lyre strings, alternating between a deft flowing melody, and an unsteady one interspersed with painfully flat notes, and he couldn’t help but smile.
“Sir, I don’t want to do sword drills anymore.”
“I don’t feel like they’re helping. They’re not suited to the way I fight, or the constructions of weapons crafted in Tartarus, and I’d fight more effectively if I could develop my own techniques and combine them with my cast-” Zagreus’s words tumbled out quickly.
“All right,” said Achilles.
“Really?” Zagreus looked relieved.
“You’ve made a convincing point, no more sword drills. You’ll run ten laps around the courtyard instead.”
“Oh, come on-“
“Exercise is always good for you. Get going.”
Zagreus made a show of groaning and rolling his eyes, but he grinned back at him before setting off.
It was the first time they fought each other to a standstill. The walls and floor of the training room, built to withstand their might, were marred with more cracks and gouges than could be counted. Achilles called off the battle first, but had the sun revolved in Tartarus, they could have fought from morning to night. The exhilaration of it was more than anything he had felt in a long time.
“I think you’re ready for a new weapon,” he said, breathing heavily.
“Yeah?” Zagreus was slumped on the floor, pressing his face to the cool stone tile. He idly turned his obsidian blade over.
“You’ve outgrown that Blade of Death, the balance of it is just slightly off in your hands. A new weapon might be just what you need to gain the edge, something that belongs to you.”
Zagreus sat up eagerly. “Sounds like a trip down to the armoury.”
The armoury remained utterly magnificent and opulent beyond anything in the mortal realm, even as the rest of the House of Hades was crumbling under slow decay. The glory of a king was reflected by the state of his treasury, after all. No matter how many times he’s been here before, Achilles’s breath still caught each time he looked upon the collection of weapons, each resting in its gilded display case. Even Zagreus, born and raised in the House, took a moment to admire it in quiet awe.
“I still can’t believe my eyes,” Achilles said. “It’s incredible, to see so many legendary weapons across the ages, all in one place.”
“I can’t imagine why Father collects all these,” said Zagreus. “Most of these were forged on Olympus, don't know why he’d want to keep them.”
“Lad, these weapons have more history attached than many heroes do. Surely you know of some of them.”
“Well,” Zagreus pointed a sword mounted in the center of a wall. A sharp, straight blade with a wicked claw curving out of one edge. “That’s Harpe. Don’t know why he has to put it on display like that,” he grumbled. “It’s kind of insensitive, Dusa has to dust this place every year.”
“Here’s the Helm of Hades, makes the wearer invisible.” Zagreus grinned as he patted a heavily padlocked case. “When I was young, I took it from the armoury and wore it around for five whole days. Father’s kept it under lock and key since then.”
He gestured at a two-pronged spear. “That’s Varchas. Father wielded it during the war with the Titans, but that’s about all I know about it.”
“You know nothing about the Titanomachy?” Achilles asked. How unexpected, for the Son of Hades himself to be ignorant of his own heritage.
“He doesn’t like to talk about it. Or anything about his siblings.” Zagreus shrugged.
“Of course, that’s understandable,” Achilles said quickly. “Well, I’m no storyteller, and the ones I know of are only from the mortal perspective. But If you wanted to learn a little more, I’d be happy to tell them for you.”
“I'd like that, sir. Maybe some other day?” Zagreus said earnestly.
While Achilles took stock of a rack of swords, Zagreus strolled over to another display case. “Hey, I think this one used to be yours.”
It was an immaculately crafted bronze shield, every inch of it covered in intricate carvings. The sea and sky, the hunt and harvest. A tiny kingdom, entire of itself, revolving around its polished surface. Truly a masterpiece that only Hephaestus could have forged. Achilles remembered it gleaming with blood and ichor on the sun-baked Trojan battlefield. Under the torchlight of the armoury, it was dull in comparison.
“It’s amazing,” Zagreus pressed his face close to the glass.
“It sure was something,” said Achilles. He placed a hand on the case. “I… always find it a shame when weapons are cast aside and hung up for decoration.”
He paused while he struggled to find the right words. “A weapon deprived of its purpose, it’s nothing more than a piece of metal. You understand, lad?”
Zagreus scuffed his feet on the floor. “Yeah. I mean, I know what poets say about weapons having souls is just a metaphor, but maybe it's got some truth, in a sense. They’re born and they die, like everything else, and they end up here as their resting place.”
“Well said,” Achilles chuckled. “But maybe that’s not a perfect analogy. A weapon can regain its life, after all. A new hero picks it up, generations after it’s been forgotten. I don’t want to ever hold this shield again, but if you want to take it up, I’d be honoured.”
“I… I don’t think I can, Achilles. I mean, it’s beautiful, but it doesn’t feel right.”
He nodded. “Let’s keep looking then.”
There he found it, the Stygian Blade, buried in a pile of crates at the back of the armoury. He picked up the broken pieces, and brought them over to the prince.
“Here, take a look at this.”
Zagreus paused mid-swing of a sword routine, he tossed his weapon onto the growing pile of swords by his feet.
“I found it like this,” Achilles said apologetically. “There’s not much of it left.”
“No, no, I could put it back together, I’m sure I can.” Zagreus gingerly took it from him, still awestruck. “I can practically feel it calling out to me.”
“You’re sure this is the one?”
“Yes, it’s perfect,” he looked to be bursting with excitement. “Thank you so much, sir.”
For the first time, Zagreus had bested him. Achilles had been knocked on his back, stunned by the strength of Zagreus's cast. He brought his blade down over Achilles’s heart, just like he’s been taught. But there was a flash of hesitation in his eyes. His hands trembled slightly, and he followed through just a little too slowly. Achilles had just enough time to move on instinct and hurl his spear upwards, aimed at Zagreus’s undefended neck.
A shower of ichor rained on him. Achilles laid on the floor with Stygius impaling him there. He choked and thrashed, his half-corporeal form instinctively struggled for the air he didn’t need. He couldn’t summon the strength to wrench the blade off him.
He stared at the ceiling, forcing himself to take deep breaths as he counted down the agonizing moments for Zagreus to reform. His vision blurred at the edges. He could only think of how this would be the first time Zagreus came out of the pool without him there, and it hollowed him out with regret.
Distantly, he heard a cry of his name, and footsteps frantically racing down the hall. Then Zagreus was standing over him.
“Shit, shit shit. Achilles, I’m sorry, I’m so sorry- what- what do I-“
“Just- get it over with.“ he croaked.
He shut his eyes, felt the blade pull out, come down again, and then there was blissful nothingness washing over him.
He blinked and sat up, freeing himself from the blade, now that he easily passed through physical matter. Zagreus was still standing over the sword, his knuckles turning white with how tightly he gripped the hilt.
“I... I’m sorry,” Zagreus said again.
“It’s all right, it’s all right.” He passed his hand through the general area of Zagreus’s shoulders. “Let’s get you sitting down somewhere.”
They shared a drink in the lounge. Zagreus was sprawled out on one of the couches, eyes closed and breathing evenly. Meanwhile, Achilles had to concentrate hard on just holding his own goblet. He grimaced as he took another sip of the wine mixed with lamb’s blood. The taste was awful, but it would help to restore some vitality to his form, stitch his spirit back to fighting shape.
“I owe you an apology,” Achilles said. His voice sounded faint and distant even to himself, like he was underwater.
“What for? I messed up back there, and I overreacted. I’ll just have to do better next time.”
“Listen to me, lad.” Achilles pressed on insistently. “I was never worried that you wouldn’t be strong enough. It’s the opposite. I was afraid of you.”
“Really? Afraid of me? What happened to 'fear is for the weak'?” Zagreus laughed, but there was hesitation in his voice. Of course, the mortals in the living world wouldn’t see him as the kind boy he’s come to know. Zagreus, the Chthonic Prince, the Great Hunter, would be truly terrifying in their eyes.
“I had to make sure you understood that war and death is not a game to mortals," Achilles explained. "I feared that one day you'd be responsible for bringing more of it to the world above. Not that I could stop you from taking up your post, if that is your fate. But I thought... as your mentor, the least I could do is prepare you to the best of my ability."
“Oh... well, you could have just told me.”
The absurd simplicity of his statement, how obvious he made it all sound, made Achilles laugh despite himself, and Zagreus shot a grin back at him. “I thought that showing rather than telling would be more effective. But it’s my responsibility to teach you properly. I made you face trials before you were ready for them, that was my fault.”
He glanced over at the prince. He still looked so young, Achilles really didn’t understand why everyone was in such a hurry to make him grow up so fast, when he had nothing to do but wander these halls, waiting to inherit the throne from an immortal father.
“I hope this doesn’t mean what we have is over. Our training sessions, I mean," said Zagreus.
“One day I'll have nothing left to teach you.”
“But not today, I’m still not as good as you,” Zagreus protested.
“You’re the first person who can claim to have defeated me in combat. You can at least take some pride in that.”
“Hmm,” Zagreus finished the last dredges from his cup, eyes closed in thought, attempting to savour this small taste of glory. “Can’t be right, you must have been killed in battle by someone.”
“I’d already lost my will to fight by then. I think anyone who witnessed that moment would not count it.”
“Fine,” Zagreus accepted it. “But there’s still plenty more you can teach me.”
“...Yes, if you’re still willing to learn from me, after all this,” said Achilles.
In his time in the House, he has learned that the underworld operated on different laws. The forces that ruled over the mortal world did not dare to touch this realm. So maybe, in this deep, sheltered place, there could be war without loss, glory without suffering, as unthinkable as it may be. He’d at least attempt to understand the laws of immortals, for Zagreus’s sake.
His mistake wasn’t preparing Zagreus for the wrong thing. It was trying to hammer compassion in him through pain. It was believing he could show him kindness while still obeying Master Hades’s will. Of the two, he knew which way he would choose, without doubt this time.