"Sherlock?" John reached forward, resting his palm gently on his companion's elbow. "What's going on?"
The taller of the two reached into his coat and withdrew a long, thin knife from a pocket hidden under his arm. "Get behind me, John."
"Sherlock?"
A hooded figure had stepped from the shadows, a bloodied blade clutched in his pale fingers. As the man stepped forwards out of the alleyway and into the harsh fluorescent light of the street, he shook his head. The thick black hood fell backwards, and a mop of dirty blonde hair flopped forwards over his eyes. He turned the blade in his hand, cocking his head to one side as though to consider the pair of men stood before him.
"It's true then." His drawling accent had a slight American tinge to it, and he pursed his lips as he took another step forwards, stepping into the gutter. With every word, he edged forwards across the road, the blade turning over and over in his fingers. "You can't hide from the Clave forever, Sherlock. One would have thought you'd try and shield yourself from the public eye, but you've gone and done it this time. Well I've got some news for you." The man had reached the pair now, and this close John could see that he was little more than a boy. He was just as tall as Sherlock with cheekbones and a disposition to match, but his eyes were not quite as lined, and his jaw kept the slightly rounded shape of youth.
"What are you?" Sherlock hissed, the tip of his knife pressed against the neck of the youngster as he stood but an arm's length away from the detective. The harsh orange light of the streetlamps glinted off both blades, illuminating the smooth planes of the boy's profile as he laughed up into Sherlock's face.
"I'm one of you. And if you knew what's good for you, you'd take yourself and your little mundane friends off into the countryside. Lie low for a few years and let the professionals deal with this… fiend… you find yourself so occupied with."
"You say you are just like me- but you are naive. Inexperienced. I've fought my fair share of demons young boy, and by no means are you a professional when you compare yourself to me."
"Demons?" John let go of Sherlock's arm and stepped forwards, planting himself between the two men. "What's going on?"
The young boy pursed his lips once more and dropped the arm holding his knife to his side, rolling his eyes and pushing John back towards Sherlock with a flick of his wrist.
"I'd have thought you'd at least tell your boyfriend what you are, Holmes."
Sherlock exhaled, dropping his knife to his side and pulling John behind him once more. "Now is not the time."
"Oh we all know why you left. Why you turned your back on the Nephilim. It's no secret, you know. You're not the first and you won't be the last, but you're in danger. You've got a target painted on your back, Sherlock. You and everyone you love are at risk. You're flying high now, but if you carry on in this way you'll all fall."
"Why should I believe you?" Sherlock's knuckles were white around the handle of his knife, his dark eyes stony and fixed on the face of the young boy before him. His voice trembled, his head shaking slowly from side to side as hot tears pricked at his eyes. This wasn't happening.
"Moriarty. That's who you're after, isn't it? He's working for Sebastian. Your mission tonight was a trap. He was going to kill you, take down you- and everyone you love- just like that. And you'd have walked right into it if I'd not turned up to stop you. Yet still, you refuse to listen to me."
"Why should I trust you? How do I know that you aren't working for him- this Sebastian?" Once more Sherlock stepped forwards, putting himself between John and the mysterious blonde American. His eyes burned with fury as he lashed out with his hand and gripped hold of the boy's neck with his slender fingers, lifting him gradually off the ground.
The boy choked, clawing at Sherlock's hands as his cheeks turned red. He kicked out with his foot and hit the detective in the chest, winding him and sending him stumbling backwards into the wall. Landing nimbly on his feet, he tucked his knife into his belt and bent over.
"Because if I were, I'd have killed you by now." Wrapping his hands around Sherlock's wrists, the boy pulled the detective upright and pushed him towards John, staring them down with a mischievous glint in his eyes. "Jace Herondale. Shadowhunter."