Chapter Text
Dean pushed open the apartment door, shouldering it wide as Sam stepped in behind him, both of them dragging the weight of their latest witch case through the threshold. Their jackets were singed, boots muddy, and Dean was about ready to collapse onto the couch with a cold beer and a grilled cheese the size of his face.
Instead, he walked into what looked like the tail end of a magical shouting match.
Castiel stood rigidly in the center of the living room, wings twitching with restrained fury. Across from him was a man Dean didn’t recognize—same height as Cas, but dressed like someone who’d lost a fight with a glitter bomb. Expensive coat, glinting rings, smug face. Everything about him screamed high-maintenance.
The air in the room was crackling, and not just from angelic temper. Dean could tell this argument had been going on for a while. Neither of them even noticed the Winchesters until Sam cleared his throat loudly.
They both turned at once. Castiel’s jaw clenched, and the glitter guy’s eyes narrowed with an emotion somewhere between frustration and exasperation. Dean was instantly on edge.
“What the hell is going on in here?” he asked, tone flat but firm.
“We were arguing,” Castiel said matter-of-factly, as if that explained a damn thing.
“Well yeah, no kidding,” the stranger muttered, rubbing his face. “Your humans are just as observant as I expected.”
Dean stepped forward. “Hey, watch your mouth. Who the hell are you supposed to be?”
The man dropped his hands and smiled like he’d been waiting for someone to ask. “Magnus Bane. High Warlock of Brooklyn. And apparently—” he waved toward Castiel “—my dear uncle.”
Dean blinked. “Warlock?”
“Half-demon,” Magnus replied with casual flair. “Half-human. I throw parties, save the world, wear fantastic shoes. Problem?”
Sam made a sound somewhere between a scoff and a choke. “Half-demon?!"
Cas took a step forward, voice like ice. “Sam. Calm yourself. Magnus is not a threat.”
Magnus rolled his eyes. “Unless I’m provoked.”
Dean crossed his arms, eyes darting between the two. “So, you’re saying this guy is your… nephew?”
Castiel nodded. “His father is Asmodeus. Asmodeus is my brother.”
Dean rubbed his temples. “That’s—yeah, okay, let’s file that away for the next family reunion. Still doesn’t answer what he’s doing here.”
Magnus folded his arms, tone shifting. “Classified magical business. Doesn’t concern you.”
Dean was about to shoot back something snarky when Castiel cut in. “It does concern them. You’ll need their help.”
“Help with what?” Dean snapped. “Fixing your glitter stash?”
“They’re not mundanes,” Cas said coolly. “They’re Shadowhunters.”
Dean blinked. “Wait. Us?”
“Yes,” Cas replied. “You just didn’t know.”
Magnus squinted at them, curiosity finally cutting through his attitude. “Shadowhunters? Like Clary?”
Dean groaned. “No way. That’s not even—”
Magnus sighed. “Fine. If that’s true, which Institute are they supposed to crash at?”
“Your boyfriend’s one, obviously,” Cas said.
“Oh, hell no.” Magnus turned on him. “They’re not staying at the New York Institute. We don’t need more sword-swinging roommates.”
“It’s not your decision,” Cas replied, stone-faced.
“Fine. Let’s go ask Maryse, then.”
At the New York Institute
Dean didn’t love portals. He especially didn’t love being dragged through one while still trying to mentally unpack the "you're a Shadowhunter" bomb. He and Sam followed the angel and his sparkly nephew through a gothic fortress of steel and stained glass. They climbed the stairs, passed paintings that moved when you weren’t looking, and entered a large foyer.
A tall shadowhunter with blue eyes and a brooding aura glanced up, visibly tense—until Magnus gave him a smirk and a quick peck on the lips.
“Sorry for the little scare, darling,” Magnus said. “We need a favor. Hoping your mom says no.”
Alec looked from Magnus to the Winchesters. “What kind of favor?”
Dean raised his hand. “Just need a place to crash.”
Alec frowned. “Why would mundanes stay at the Institute?”
“They’re not mundanes,” Magnus interrupted. “Uncle Cas here thinks they’re Shadowhunters. Supposedly.”
Alec blinked. “Uncle Cas?”
“Yes. My father’s Asmodeus, which makes Castiel my uncle. Try to keep up.”
Alec looked at Magnus like he’d swallowed a rune wrong. “You have an angel uncle and never thought to mention that?”
“I was going to bring it up,” Magnus replied innocently, throwing in a wounded pout for effect.
Dean didn’t even try to hide the eye roll.
Alec just sighed and waved them along. “Come on. Let’s find my mom.”
Dean watched the halls closely. Sam, predictably, was distracted by every rune-inscribed relic and training blade mounted on the walls. Dean had to tug him along like a kid at a museum.
Eventually, they reached the library. A tall woman—clearly in charge—looked up as they entered. Her sharp eyes softened just a little at the sight of her son.
Magnus launched into a half-dramatic, half-exasperated explanation. Maryse listened, then turned to Dean and Sam with a cool, assessing gaze.
“If Castiel believes you’re Shadowhunters, then you are welcome here,” she said with grace. “I’ll have rooms prepared.”
Dean glanced at Magnus, who was now muttering something about antique mattresses under his breath.
This is going to be a long damn week, Dean thought.
Maryse led them to a row of spartan guest rooms. One bed, one nightstand, just enough room to breathe.
“Thanks,” Dean said, giving her a nod.
As the door shut behind them, he looked over at Sam, who was already inspecting the walls for secret weapons or glowing glyphs.
Dean flopped onto the bed and stared at the ceiling.
“Shadowhunters, huh,” he muttered. “Just once I’d like the family tree to not come with new responsibilities.”