Alec knew that something was horribly wrong from the moment that he saw the flashing neon lights in the long, slim windows of his parents' house. He dropped from a run to a jog, ripping his headphones out of his ears, and was greeted by the sound of excessively loud music, streaming towards him from the house in front of him. Another bad sign.
The nail in the coffin was delivered swiftly, when the front door swung open and a teenage boy stumbled outside, shooting Alec a fleeting wary look, before retching and throwing up violently onto Alec's father's prized petunias. The kid glanced back up at Alec, mustered up a weary smile, and disappeared back inside.
"For God's sake," Alec groaned, running a hand through his sweaty hair. He couldn't believe the audacity of his little sister; he disappeared for maybe an hour, simply for an evening run around the city, and came back to find a party in full swing. He was going to murder Isabelle, slowly and painfully.
Alec shoved the door open violently, almost smacking the petunia-boy in the face, but was too angry to bother apologising. A few people that he knew vaguely from school greeted him, but Alec ignored them all, striding into the living room, eyes scouring the premises for Isabelle's long curtain of dark hair.
"Hey, Alec," a familiar voice at his shoulder called to him above the music - a voice Alec couldn't ignore. He turned towards it, coming face to face with the even, golden eyes of his best friend, Jace Herondale. "You okay, man?"
"No," Alec snarled, his eyes still taking in the horror of their trashed living room - paper cups and broken glass littering the floors, a strong stench of sick and alcohol filling the air. "Where's Izzy?"
Jace laughed, patting Alec patronisingly on the shoulder. "I don't know, Alec. But you need to lighten up a bit."
"Lighten up?" Alec was incredulous. "I'm the one in charge here, while Mum and Dad are away -"
"A juvenile argument," Jace noted with a shrug.
Alec ignored him. "- and I leave her alone for not even an hour and she goes and throws a bloody house party? Do you know how much trouble I'm going to be in if any of this gets back to our parents? If anything's broken, if anything happens, if -"
"Hey, hey." Jace held up his hands. "Okay. I get it. Don't panic." He placed a hand on Alec's chest, and Alec, despite his frustration, felt a flickering thrill at Jace's touch, at the warmth that spread from Jace's slender fingers across Alec's chest. "I'd ask Kaelie - I saw her talking to Izzy maybe ten minutes ago?"
"Thanks," Alec breathed, offering Jace a sliver of a smile, as he wound his way towards the blonde barbie-doll of a girl, Kaelie, his golden-featured angel (in looks, if not personality) of a best friend at his shoulder.
"Looking for Isabelle?" Kaelie offered a high pitched laugh in response to the obvious distress playing across Alec's featured. "Upstairs."
Alec followed her directions, leaving Jace to flirt shamelessly with the girl, and wound his way upstairs, dodging hordes of drunk teenagers. Fortunately, the upper floor of the house was relatively deserted, and Alec was relieved to see that most of the doors, including the ones leading to the bedrooms of him and his parents, were untouched.
Alec strode purposefully to Izzy's black-and-pink painted door, his anger building slowly from mild frustration into undisguised fury. How could she be so irresponsible? She had completely ignored his pleas, utterly disregarded the advice of their parents. How did she think this would be okay?
Alec's fingers closed around the door handle and he threw it open, already ranting, "Isabelle Sophia Lightwood -"
He was interrupted by a shrill scream and the thud of about 60 kilograms of teenage girl hitting the floorboards. Alec was thrown by the commotion, his eyes widening as they focused on the scene in front of them.
His sister was sprawled across the floor, having fallen off her bed in the shock of his intrusion, and - rather disturbingly - was dressed only in a hot pink bra and a black miniskirt. Perhaps more disturbing was the figure looming over her, half on the bed and half on it, an arm still caught around Isabelle's waist. As Alec took in the figure, it became increasingly more disturbing - a boy of maybe eighteen or nineteen with tousled black hair, a face with such sharp, sculpted angles that Alec imagined you could cut yourself on them, a pair of mysterious, alluring yellow eyes, lined with strikingly dark lashes, and a torso that was muscular and so profoundly and unapologetically bare that Alec's eyes were drawn scandalously towards it.
Once Alec's brain began to function, he took in the lipstick marks streaked across the boy's neck and face, in the same plumb shade that Izzy wore on her lips, proximity of their faces, the way his hands were caught lightly about her body.
The long and awkward silence was broken by Alec groaning pitifully as his brain pieced everything together and he realised what was happening.
Isabelle recovered the fastest, scrambling to her feet and grabbing her discarded top from the floor, shimmying into it as she snapped, "Haven't we discussed knocking, Alexander?" at her brother.
Alec could feel himself blushing furiously as he endeavoured to look anywhere, and at anything, other than the half-naked, gorgeous - did he really think that? Alec quickly shut down that train of thought - male specimen in front of him, who was making no effort to dress himself, instead fixing Alec with the sexiest smirk the boy had ever seen. "Haven't we discussed being responsible, not throwing goddamn parties every time you're left alone for more than five minutes, and generally doing your best not to make my life unnecessarily difficult while Mum and Dad are away?"
Alec said all of this in a single breath, and found himself slightly winded by the end of it. He paused to inhale a mouthful of air, and his eyes drifted back towards Isabelle's partner in crime, who was now perched on her bed, arms folded across his muscular chest. There was something maddeningly casual about him, something in the lazy lines of his posture, the slant of his angular, lightly lidded eyes.
Alec cleared his throat, tearing his eyes once again away from the boy in front of him, blinking to clear his head. He should feel angry, should be tearing this boy to pieces for touching his little sister, but there was something about him that threw Alec off, made it impossible for him to think straight.
"Come on, Alec," Isabelle was saying, her arms folded over her slender waist. "It's not a big deal. I'm going to clean up, afterwards - and Mum and Dad aren't home for another two weeks."
"Ignoring the party," Alec snapped back, "which is, by the way, a very big deal which we will be discussing later, the fact that you have a…" He was suddenly unsure of how to express this. "A…" He gestured wildly in the direction of the boy. "A strange boy in your bedroom. In a...compromising position -"
Isabelle finally had the grace to look embarrassed, a slight colour rising into her cheeks. The boy, meanwhile, simply laughed - actually, properly laughed, to Alec's indignation. "We were just…"
"Just what?" Alec gawped at her. "No. No, no, no. You just pretend that all of this - that none of this -" He paused, fixing the boy with a glare. "I think you need to leave."
Isabelle folded her arms and opened her mouth argumentatively, but the boy cut her off with a flick of his hand. "It's fine. Izzy. I'll go."
He scooped his jacket off the floor and slung it cockily over one shoulder, turning to drop a wink and a wave in their general direction. Alec felt the energy draining out of him as Isabelle pouted. "Call me?" she demanded.
"Of course."
The boy slunk through the door and Alec sunk to the floor, burying his head in his hands.
"Alec -" Isabelle began.
Alec shook his head. "I don't want to talk about it."
Isabelle watched him for several long seconds, before apparently deciding that she was just getting off easily. She said nothing more, and, when Alec finally looked up, ten minutes later, she was gone, and he was alone on the wooden floor of her bedroom.