Sirius Black stood rooted in the alleyway, heart hammering, every instinct torn between disbelief and a rising, wordless dread.
The boy—no, the being—before him had just shed one identity and stepped into another as if it were a second skin.
"Hello, Godfather," the boy had said.
And now, that word Godfather clung to Sirius's ears like a curse.
The boy—Cassius, though Sirius did not yet know the name—tilted his head slightly, those too-familiar green eyes flicking down the alleyway.
"We shouldn't linger," he said quietly, his tone clipped but certain, the kind of voice that commanded without needing to raise itself. "There are still people watching the Ministry exits. Some of them not… friendly."
Sirius blinked, struggling to pull himself out of the daze.
"You—how—"
"Later." The boy—Cassius—reached out and grasped Sirius's wrist with surprising strength. "Come on."
Before Sirius could argue, he was being pulled through the maze of narrow London streets, Cassius weaving between pedestrians with the unerring certainty of someone who knew exactly where he was going.
A cab appeared at the curb as if summoned.
Cassius opened the door, climbed in, and jerked his head toward the seat beside him.
Sirius hesitated for a heartbeat, then followed.
The door slammed shut behind them, sealing them off from the world.
"Where to?" asked the driver, a burly man whose eyes were glazed with the blank indifference of someone under a mild Confundus charm.
Cassius leaned forward. "Number Twelve, Grimmauld Place."
The driver nodded, and the cab rolled forward into the pulse of London traffic.
Sirius's blood ran cold.
He hadn't heard that address spoken aloud in more than a decade.
The words themselves carried a weight, a magic, that made the hair on his arms stand on end.
He turned to stare at the boy beside him. "How—how do you even know about Grimmauld Place?"
Cassius didn't answer right away.
His gaze was fixed out the window, watching the blur of people and buildings go by.
"You'll understand soon," he said at last. "There's... something we need to discuss."
Sirius's jaw tightened.
He wanted to demand answers, to curse, to shout—but there was something in the boy's tone that made him stop.
Not arrogance.
Not manipulation.
Just quiet, steady confidence.
For the entire ride Sirius tried to figure out how this young man with her eyes, knew about the secret.
Grimauld place had since during the war been an operating place for members of the order, and placed under a fidelius charm, only someone knowing the secret could have told him the location, which meant the order had further traitors... or could she have told him, perhaps it was him...?
When the cab finally pulled to a stop, they stepped out into a dingy, narrow street lined with identical old row houses.
Everything was drab, grey, and lifeless—the kind of place that seemed to swallow sound itself.
Sirius took a deep breath.
The air smelled of rain, dust, and ghosts.
Cassius stepped between Number Eleven and Number Thirteen.
The space shimmered faintly, stretching like fabric.
And then, as if exhaling, the hidden townhouse unfolded from nothingness.
Number Twelve, Grimmauld Place.
Sirius stared up at it, his throat tight.
The curtains were drawn, the windows coated in grime.
The Black family crest, tarnished but still visible, gleamed faintly in the low light.
Cassius turned to him.
"After you, Lord Black."
Sirius swallowed, nodded once, and stepped forward.
The door creaked open at his touch.
Inside, the air was thick with decay and dust.
The smell hit him first—old wood, damp stone, and something metallic and faintly rotten.
The dimly lit hall stretched out before them, lined with portraits of gaunt, sneering ancestors.
Their painted eyes tracked his every movement with disapproval.
On the walls, the heads of long-dead house-elves hung like grotesque trophies, their leathery faces frozen in eternal servitude.
Sirius's stomach twisted.
"Merlin," he muttered. "It's worse than I remember."
Before he could take another step, a shrill, familiar voice shrieked from the shadows.
"FILTH! BLOOD TRAITOR! YOU DARE RETURN TO THIS HOUSE—"
Sirius flinched.
"Oh, not now—"
But Cassius was already moving.
With a flick of his wand, heavy velvet curtains slammed shut over the portrait of Walburga Black.
Another quick twist silenced her voice completely, leaving only the faint vibration of her fury trapped behind the drapes.
Sirius blinked, stunned.
"I—Merlin's beard. You shut her up."
Cassius shrugged.
"You'd think after all these years someone would've done it sooner."
A ghost of a smirk tugged at Sirius's lips.
"I like you already kid."
They made their way deeper into the house, the boards creaking beneath their steps.
The place felt more like a mausoleum than a home.
Every shadow seemed to whisper.
Every corner reeked of memory. dark and accursed.
On the second floor, Cassius pushed open the doors to what had once been the family library and study.
The air inside was thick with dust motes drifting through slanted light.
Shelves sagged under the weight of ancient tomes and relics preserved thanks to wards and spells to protect them even after years of neglect.
Sirius sank into the nearest armchair.
It was threadbare, the leather cracked and faded, but it felt real—solid.
For a long moment, he just sat there, breathing, trying to anchor himself.
Cassius moved silently to the other chair across from him and sat down.
His eyes, green and unwavering, watched Sirius with a calm far too old for his face.
Finally, Sirius spoke.
His voice was rough, unsteady. "You're going to start talking now, kid. Who are you? How do you know me? And why—" he gestured around them "—why bring me here of all places?"
Cassius leaned forward slightly, resting his elbows on his knees.
"My name," he said, "is Cassius."
Sirius frowned.
"Cassius what?"
"Cassius Snape," he said evenly.
Then, after a beat, "Half-twin brother to Harry Potter."
The words hit Sirius like a spell to the chest.
"What—"
"My mother was Lily Potter," Cassius continued, his tone measured, almost detached. "But my father… is Severus Snape."
The room fell silent.
Sirius's mouth opened, but no sound came out.
The name Snape echoed in his skull like a thunderclap, dredging up every memory of bitterness and rivalry and hatred from his school days.
It made no sense.
It shouldn't have been possible.
And yet the boy sitting across from him—Lily's eyes, Severus's face—was proof enough.
But just why... no how!?
Lily was already with James by that point why would she return to the man who hurt her so in school?
Just what was she thinking, and yet through it all it was his own rival whose child came to his rescue like a light in the darkness saving him from being swallowed whole.