The air was cold. The sky over the river was foggy. Percy hurried through the thickening crowd along Fifth Avenue. His sea green eyes whipped back and forth over, searching the area for any attackers. He was into a leather jacket, trying to think of something other than Annabeth.

Annabeth Annabeth Annabeth.

He ran shaky fingers through his dark hair. Annabeth, his girlfriend, was in Olympus, and had been for a week already. He knew that he shouldn't intrude on her business- he would just be a distraction and a job as big as redesigning the home of the gods was not something to be distracted from. But… in just the week she had been gone, Percy couldn't once take his mind off Annabeth. She haunted his every thought, his every dream, with pretty gray eyes and flowing blonde curls. The corner of his mouth curled into a smile before he could stop himself. He grumbled and rubbed the heels of his palms into his eyelids.

That was why he had to see her. The Empire State Building wasn't far from Camp, anyhow. Neither Mr. D nor Chiron cared where he went, so long as he didn't start another Titan War or get ripped to shreds by a Fury. And he wouldn't- at least he shouldn't…

He started down (street). It was quiet, the throng of people left far behind. He was taking a different route to Olympus, though to be honest, he wasn't paying enough attention to know if it was a way to get there at all. This was the dirtier part of town, where construction crews turned a cheek at the crumbling stone fortifications. Take the huge church building before him. It was absolutely ancient, overgrown with ivy and every crack filled with moss. Its towers were broken off into little stumps of concrete jutting from the top of the building, and the façade was buttered with and ash and dirt.

Percy narrowed his eyes- there was something fishy about the place. And it wasn't just the smell, which was like the dumpster behind a seafood restaurant. He stopped in his tracks and pulled the pen from his pocket. The air was silent as he positioned himself for attack. Every muscle in his body tensed as a shrill, scraping noise tainted the air.

The monster came out of nowhere. Percy leaped back, uncapping Riptide, releasing the glimmering, bronze blade. The monster was like nothing he had seen before; it had the bulk of a Minotaur, the wings of a Fury, but was made of shadow and darkness and seemed to exist wholly on the dust between worlds. It had a million, razor-sharp, all gnashing and dripping a dark sap.

Percy didn't back down. He felt the adrenaline wind in his legs and leaped at the dark monster. He brought his sword down over its head as it lashed out with its fangs. Percy tumbled back to avoid the deadly jaws. He crouched on the other side of the street, boiling in curiosity. What was that thing? He had never fought one before, and none of his lessons on Greek mythology (or in his case, history) told of such a thing. If he could figure out what it was, then maybe it would be easier to fight it using its weaknesses. Percy stumbled over a mental checklist of monsters.

The creature exploded with energy. It screeched with fowl rage and tried bulldozing him with its raw strength. Percy rolled and stabbed at its underbelly. It protested and hopped to the side. Dark fluid began streaming from its stomach, and it howled angrily. Percy's mind was flying- what was it? Why wasn't it crumbling to ash? Was it something more than a monster? To make things worse, an image of Annabeth fighting with her bronze dagger, brave and beautiful, floated through his mind. During his distraction, the creature charged him again.

It sliced his cheek with a knife-like tooth. Percy sliced at it, ripping through membranous skin that must have been hidden behind the shadows. It shrieked, becoming chaotic, its movements unpredictable.

"Think," the boy muttered. If he wasn't so distracted, perhaps it wouldn't be so difficult to fight. "Think like Annabeth."

His heart softened at the thought of her. He mentally punched himself in the face. The creature approached him in a mad dash across the street. Something split from the sidewalk and smacked the monster dead in the chest. It fell; black liquid drained from the wound while it groaned, then it crumbled and was gone.

Percy stood fluidly, holding Riptide at the ready. "Who's there?" He asked. The tip of a long bow and a dark head came forward from behind a stone wall. "Thalia?" Percy wondered.

The rest of the figure emerged from its hiding spot. It was lean and dressed in a black hoodie and some sort of leather gear, unlike what they wore at Camp Halfblood. It flipped the black hair from its face to reveal startlingly blue eyes, and a pale, masculine mace. Percy blinked, "Not Thalia?"

The boy- probably no older than seventeen- turned a disapproving look at him. Before he could open his mouth, another young man popped out from behind the wall. He ran a hand over his golden hair and smiled. "Nice sword you got there! Didn't know the Iron Sisters were much for working bronze- or is that gold?" He approached Percy with a curious smile. He stretched out his hand. "May I hold it?"

Percy gripped Riptide, skeptical now of how this guy could see through the Mist. "No."

The young man frowned dramatically, then grinned. "All right. Then you must be a better fighter than you seemed out there."

This time Percy frowned, then began chuckling. "You don't even know, man." His brain skimmed over unpleasant memories of Medusa's snake-eyed head, the sticky blood of the Minotaur and countless other monsters, and worst of all Kronos- falling to pieces at Percy's feet.

The guy peered at him quizzically and outstretched his hand once more. "I'm Jace. Nice to meet ya."

The young man behind Jace groaned. "No Jace, no more making friends with mundies. That's brought us enough trouble already."

Jace shook his head. "This guy isn't a mundie."

He grabbed Percy's arm and searched it for something unknown to Percy. "Lots of scars here, but no Marks," he muttered. Percy raised an eyebrow.

"Marks?"

Jace set down his arm and took his shoulders instead. He leaned in close, looking into Percy's eyes, then shuffling his fingers through his ebony hair.

"Uhhh…"

"Sorry if I take your breath away," Jace said. "I tend to have that effect on people." He lifted Percy's hand and searched his fingers, then, finding nothing, spun him around to face his backside.

Percy struggled free of his grip. "Okay, man, I think that's enough." He lifted his sword again. "Now tell me what you want from me."

Jace stepped back, palms up defensively. "Just trying to find your warlock's mark. But you don't have one." He looked back at the other boy with an uncanny resemblance of Thalia. "You might be right, Alec. Maybe this guy is a mundie."

Percy shook his head. "What's a mundie? And what are Marks? And what was that monster?"

Jace rubbed his chin. "You can fight?"

"Yeah."

"Then I need your help."

Percy searched the guy's face and made a gesture. "What do you need?"

Alec marched up to Jace mumbled something into his ear. Jace shrugged it off and turned his attention back to Percy. "All right, look. I can't tell you much. I don't know who you are, or what you are, though I expect you're no more than a mundie with skills, and an awesome sword. But, you must have your own secrets to keep- and if you help me and my friend here, I won't bother asking you anything in return."

Percy thought about this. "What's in it for me?" He didn't really care, just wanted to know.

Jace shrugged. "I won't kill you."

Percy smiled. "I think I could kill you before you could kill me."

"I don't think so."

"Well I do."

Percy didn't normally challenge people this way; he knew he was strong, but he wasn't arrogant or proud. But this Jace guy had a way of getting under his skin and making him want to prove his power.

"Stop," Alec said. "You guys can't just out-kill each other. There are bigger problems right now and we don't need any trouble with the Clave."

He glowered at Jace who sighed, putting on a serious face. "That thing you saw- that Eidolon- it was a demon. A shapeshifter. There are tons of them running rampant in Manhattan, the Angel knows why. It is our job to stop them before they kill everyone- or mate with everyone- either way, bad things happen. The point is…"

Percy met the guy's golden eyes. "Will you come demon-hunting with us?"

Percy scratched his head. Anything would be a relief from thinking about Annabeth. He guessed it wouldn't hurt, especially if there were monsters loose in the city. These two raised a lot of questions- their job was to hunt demons? They could see through the Mist? Maybe they were demigods? It didn't matter- they wouldn't ask questions if he didn't.

"Why not?" Percy replied.

Jace grinned, bearing a resemblance to he had heard of Lucifer. "Great," he said. "I'll grab you some gear."

Percy glanced at the black, leather straps that secured the dozens of oddly luminescent blades to their hips and chests and backs. That wasn't really his style. "Actually," he said, unzipping his jacket. "I'm good."

Under his jacket he wore a Celestial bronze breastplate that looked somewhat like an Ancient Greek warrior's. He pulled his orange Camp T-shirt down from being caught underneath it.

Jace looked impressed. "Nice. Quite the fashion statement there; I'll call it 'Teen Greek.' It's great because you could rhyme it with 'fashion week.'"

Alec grimaced at the horrible joke. "No, no," Percy said. "That's actually pretty good." Jace bowed.

"Thank you- er…"

"Percy. Percy Jackson."

"Catchy," Jace noted. "Adds to the whole Greek appeal. Do you think you could be the star model of my fashion show?"

Percy shook his head. "Let's get on with the monster-hunting."

Jace nodded and pulled a peculiar, metal gadget from his pocket. He pressed a few buttons on it, and it beeped in response. He put it away and pointed to the next street over. "That way."

And so began a most splendid day of demon-hunting.

Percy's mind cleared up as sweat rolled down his forehead. The Eidolons differed in shape, size, and strength. Some were fast, while some were slow. One took on the form of a cow; this had Percy perplexed at first, but when Jace drove a knife through its side and it burst into a giant shadowy beast, it made much more sense to him.

Percy fought with ease, taking down two or three monsters at a time. Alec and Jace were skilled in combat as well, the mysterious black markings inked on their bodies almost seemed to glow while they fought. They made a good team, those two, and with Percy along they were even better.

Exactly forty-eight Eidolons later, they wound up on a narrow street with several apartments on either side. The device in Jace's hand- a sort of monster sensor- beeped out of control. They searched the area with their eyes but turned up nothing. "Maybe it's in one of these houses?" Percy said.

Jace shook his head. "Look."

On the road in front of them, a little brown rat scurried around in circles in the night air. Jace and Alec pulled their weapons and stood defensively. "Looks dangerous," the blonde boy mumbled. Percy strolled forward and lifted the rat from its tail.

"This is a rat."

Jace and Alec shared a glance. Percy watched as the squirming rodent grew and transformed into a shadowy monster as large as an apartment complex. Percy stumbled backwards and uncapped Riptide. "I guess it's not the first time I made that mistake."

The monster released a thriving roar that echoed throughout Manhattan. A door flung open in one of the flats and man stepped outside in a satin robe and slippers. "What is that racket? Haven't any of you shadowhunters heard of beauty sleep?"

The dark beast loomed over the street and screeched, shredding the fine muscles in Percy's eardrum. Alec set an arrow to the string of his bow and drew it back. The projectile hit the monster in its stomach, spurting with black fluid. Jace threw several knives but nothing seemed to disturb it. After several moments of silence, it roared again and charged at the three fighters. Percy dodged to the side of the street and then back, slicing at the beast with clever sword strokes.

It streamed black blood- ichor, Jace had called it. It stung Percy in several spots, burning like the poison saliva of the snakes on Medusa's head all those years ago. When the monster turned on him to attack, he parried its slashing teeth and ran a few steps around it. Jace stepped in with a translucent blade in his hand. "Arthuriel!" He cried and it burst to life, flaming blue and white like a fallen star. He whipped it through the air, opening another wound in the monster's side.

"Keep working at it!" Jace yelled. Percy slipped around the wide, dark cloud and stabbed Riptide in, brilliant gold against the black. The beast roared and flipped around, but not before he had pulled the sword out and hacked it into its side. It gnashed its teeth, bouncing off the bronze breastplate on Percy's chest. He darted away as Alec shot another arrow. Jace, like a lion loping through the night, approached the beast and stabbed it with a strangely-marked dagger. It reared up and dashed down the street towards the water.

They chased him to the shores of the murky brown Hudson. The sunrise was a sliver of pink in the distance, hidden behind the formless darkness of the beast. Jace cursed. "This might be difficult. It can glide over the water but we can't- it has us more surrounded than we have him."

Percy glanced at the polluted water lapping against the banks. He smiled, sea green eyes glinting. "Well… maybe not." Alec and Jace looked at him oddly but he stepped forward, Riptide in hand. He summoned the water- perhaps not clear, but still under his command. It rose behind the monster and traced streams through the air to the son of Poseidon. He rose in it and swept to the reverse side of the shadow. It seemed just as confused as the two boys standing awkwardly in the street.

"I can't help but feel a little pathetic here," Jace said.

"Take its front," Percy replied. "I'll keep it from the back."

The three young warriors set to work, slashing at the beast with cunning and strength, with knives and swords, with arrows and shurikens, with the Hudson River. Though they sweated, they did not tire. This was their lives- fighting demons and monsters and whatever dark force came their way. Percy was, in fact, more energetic than the others, basking in his home element while doing what he was born for- despite the strangeness of the "demon."

The colossal Eidolon finally fell, a formless, dark mass, at their feet. Percy lowered to the street. It spasmed, spurting ichor on the asphalt. The man in slippers and robe strolled forward- and it was not just a robe, but a red, silk kimono, Percy noted. He sighed making a tsk tsk noise. He lifted his hand which cupped a ball of blue, sparking flames. Meeting Alec's eyes he said, "If you weren't pretty, I would not stand for this."

Alec blushed and the man sent the sparks flying at the monster and it disappeared. They stayed in silence, panting as the sun rose in an orange blossom across the horizon. Percy wiped sweat from his forehead and ichor from his breastplate. The man looked him up and down, making the boy feel uncomfortable.

"You should be the head model for a new line of fashion- Teen Greek. What with those gorgeous eyes, and the hair, and quite the physique my friend- oh, and can you rock a breastplate! Yes, you will have to do for sure. Call me?"

He handed Percy a purple business card reading, "MAGNUS BANE, HIGH WARLOCK OF BROOKLYN." He shoved it in his pocket, too embarrassed to mention that he couldn't actually use a phone without attracting a million monsters.

"Your friend here is very interesting. Congratulations on being unique, Mr…"

"Percy," Jace filled in. "Percy Jackson."

Recognition flooded Magnus' green-gold eyes. He made a little O-shape with his mouth. "Percy," he repeated.

Alec began to glower. Seeing the reaction, Magnus cleared the expression from his face. "Right, then. So long Percy Jackson, Alec Lightwood, and Jace Whatever-you-are. You will not be in my dreams, I hope."

At that he left and marched down the street. They watched silently as he entered the apartment he came from and slammed the door shut.

"Doesn't Magnus live in Brooklyn?" Jace asked.

"He likes a change of scenery." Alec replied. Percy stayed quiet.

"I think that's as many as we're going to find in one hunt," Jace sighed, hands on hips. "Forty-nine. Not a bad number."

He turned to Percy and patted him on the back. "Good going out there. There are a lot of questions I want to ask you, what with that walking-on-water crap, and your sweet pen-sword…but I'll stay true to my word and keep those questions inside."

"That's a shocker," Alec muttered.

Percy nodded. "I can't say I don't feel the same way."

He capped Riptide and put him in his pocket. There was an almost audible moan from Jace as he did so. "I guess I'll be on my way," Percy said. He nodded to Alec and Jace and started walking down the street. When he became just a figure in the distance, Jace looked to his oath brother.

"I really want that guy's sword."

It was one week later. Annabeth had just arrived home from Olympus, to the great joy of the campers and Percy especially. They were sitting on the sand, just the two of them, watching the waves splash on the shore. Percy had a pen in his hand and was doodling with it. Annabeth sat up and looked over at him. "Whatcha drawing?" She asked.

Percy looked up. "Oh, this," he lifted his arm to show the twisting, flowing designs on his wrist. "I don't really know."

Annabeth peered at the eye-shaped mark on his hand with Athena-like curiosity. "Looks sort of like runes… but not like anything I've seen before." She shook her head.

Percy shrugged, setting down the pen. "Just have a brilliant imagination, I guess."

Annabeth ruffled his ebony hair and leaned in to kiss him. "Sure you do, Seaweed Brain."

They laid back in the sand, as the warm ocean lapped on their entangled toes.