The alley breathed him in, swallowing Cassius into its narrow, forgotten throat. Shadows coiled tighter, guiding him toward a place no man, no mortal, could ever find. Not unless they were born of fire and bone, as he was.
His boots stepped onto stone older than the city itself, etched in script long abandoned. As he moved forward, the gloom gave way to flickering lanterns suspended in the air, green fire swaying gently, casting sickly hues across obsidian walls. They hovered like ghosts, murmuring as he passed. They remembered him.
He remembered this.
He had built this place. Carved it out of the marrow of the world centuries ago, when he ruled like a god-king, when mercy was weakness and power meant blood. It had been his personal oubliette. His cage for things too dangerous to kill, too useful to destroy.
And now? He was being bossed around by a woman with unbrushed hair and a child strapped to her hip, claiming he was the father. His mouth twisted bitterly. He, the 50th Demon King, now reduced to buying baby pajamas and dodging death threats from his siblings.
The descent ended at a vaulted chamber, stone walls webbed with old magic, the air thick with stasis. The green lanterns flared brighter here, casting light on the crucifix nailed to the center of the floor.
There hung the boy.
Stripped bare, his chest slick with sweat, muscles taut and trembling. His dark hair, long and unkempt, swayed around his face like silk. Horns curled along his temples, low and elegant, like twin blades curved to rest. From his back, faint outlines of wings quivered, half-formed and shivering from neglect.
Cassius slowed.
The boy's head lolled forward… then rose. Pale lips parted in a low growl. His eyes peeled open, irises glowing faint silver in the unnatural light. He took Cassius in, and a slow, mocking smirk spread across his face. "Well, this is an unpleasant visit."
Cassius arched a brow. "It sure is."
"Lost a bet? Or just here to gloat?" the boy said.
"I never gloat," Cassius replied, voice cool. "It's beneath me."
The boy chuckled, bitter and beautiful. "And yet you've caged me here for three hundred years like a pet you forgot to feed."
Cassius looked at him for a long time. His face. The raw bones of someone once proud, once powerful. "You think I don't know what that's done to you? Every action I've taken has only been a measure to make you submit."
"I know you do. That's what makes it worse."
Cassius exhaled, stepping closer. "It wasn't supposed to be like this. You were dangerous. You still are."
"Don't romanticize it. You were afraid," the boy said, tilting his head. The only thing he could remember was the blood and fire that once rained in his days. When everything was just as normal. "And maybe you still are."
Cassius didn't argue.
The boy licked his dry lips. "If you're here, it can only mean one thing…"
Cassius stopped at the foot of the crucifix. "I need your help."
A heavy and electric silence filled the air, then the boy laughed aloud. He couldn't believe what he was hearing, after three centuries of being kept in darkness. "The Demon King finally asking me for help? After three centuries of starvation and solitary confinement? Why?"
Cassius dragged a hand through his hair, the strands catching at his fingers. "Because… a lot has changed. I don't trust my court. I don't trust my siblings. And the only person I can trust now is someone who has nothing left to gain."
The boy's laugh turned into a hum. "So you need a monster."
"I need someone with teeth," Cassius said. "And no reason to betray me."
"I take it your precious siblings want to toss you from your little throne?" the boy asked, eyes gleaming. Unlike other demons, he never truly cared about the Courts. He was more fascinated with the human world, than demon kingdom. He hated the politics that came from royal houses, the traitory that always followed. But here, in the human world, he could become a legend. He could become a god of some sort, just as he once was, back in the day.
Cassius grinned crookedly. "I met a girl one night. In a tavern. Things got… out of hand. We got down and dirty."
The boy barked a laugh. "And now you're being blackmailed by her?"
"Something like that," Cassius muttered. "She called me. And she wasn't alone."
The boy leaned his head back against the iron. "What's the child's name?"
Cassius hesitated. The question never met his ears until now. So he muttered, "…I don't even know."
"Unbelievable!" the boy cackled. "I expected more from you, King!"
Cassius scowled, then looked up at the boy with something softer beneath the sarcasm. "He has my eyes. Strong magic. I couldn't kill him when I tried."
"You tried?" the boy asked, delighted. Maybe he was wrong. Maybe Cassius was just as savage and heartless as he was the last time he locked him up in this hellhole.
"He nearly destroyed an entire village… thanks to Asmodeus," Cassius said. "He's not just powerful—he's dangerous. Just like you."
The boy's laughter softened into a sharp smile. "To think… a little hybrid brat might be our next heir."
Cassius didn't respond. His silence said enough.
The boy's gaze lowered. "Release me."
"That was my plan all along," Cassius replied. "I need you, Merlin."
The name struck like thunder between them. Spoken for the first time in centuries. The boy's smile faded slowly, and something flickered in his eyes—recognition. "Merlin…" he whispered, as if the word burned.
And Cassius, for the first time in years, felt like he wasn't walking into war alone. If he was ever going to punish his siblings, he knew it would only take a monster to defeat a monster. And Merlin was just the right candidate for the job.