If Nico di Angelo knew what sort of a pain in the ass the young man he'd met on that cold, dreary autumn day was going to be, he might've considered ramming his Stygian sword through the jerk's chest the instant they met.

Well, met is a very polite way of putting it. And, frankly, can you really say you "met" someone when they bump into you, smear blood all over your favorite jacket, and then snap a monster's neck with a wave of a stick?

Confusing? Perhaps a more detailed explanation is in order.

Never let it be said that the son of Hades didn't try to pull his weight for Camp Half-Blood and Jupiter. His two homes were just that—his. And he was rather tired of being on the outside looking in.

Of course, at the time he'd confessed such to his former crush and friends, he figured they'd take it a little easy. Maybe involve him in the counselors meetings, an invitation for a quest would be most welcome—if only for a little bit of cathartic monster slaying—or maybe he could convince them to take him to the movies.

Granted, they did all of that. Happily, too, much to his surprise. But they also insisted he take some level of responsibility for some of the more time-honored traditions of the older demigod campers.

They, one should note, as in the two boys who held the most sway in his life.

Nico growled as he was bumped by yet another teenage girl looking down at her cell phone. "Going to kill Grace if he shoots that damned smile at me when I get back," he muttered. "And Jackson will be running from skeletons for a lifetime if he does his innocent routine asking how things went."

The girl and her friends turned, giggling at him and whispering to one another. Most boys, Nico mused dryly, would've probably found that flattering. Leo might have blushed.

He shoved that notion into a mental trunk and locked it tight. Clearing the way of monsters for a halfblood escort party. Well, it wasn't the worst idea Percy had come up with—that it had been his before Annabeth's had been quite a moment for all of them—but still.

Nico couldn't shake the distinct feeling that he'd been given grunt work so he wouldn't scare the new campers. A notion Leo hadn't helped.

"Don't feel too bad, Nico!" he'd crowed as he threw an arm around the boy's shoulders. "It's just that your death glare is better suited for making monsters cry for mommy than it is telling kids it'll all be okay soon. Heh! Get it? Death glare?"

That Piper had beaten him to slugging Leo's shoulder didn't diminish the satisfaction in watching him whine about it.

He stopped at the corner of the street, his dyslexia making quite a challenge of discerning the street signs as he gazed across the way at Fenway Park. Off to his left, he could hear those girls still giggling before they disappeared down the steps leading into the subway tunnel, the idle thrum of streetlights turning on as the sun came to a rest beyond the horizon. All quiet for a change.

Good. Maybe this time, things could go off without a hitch.

Naturally, it was right about the instant Nico allowed that thought to creep into his head that he felt another shoulder bump against his left arm and sent him staggering a step. His nostrils flaring, he reached up to brush his arm off and turned to level a glare at the offender's back, right at the visage of fiery orange wings spread across the back of a hooded jacket, a pointed barb on the tip of his tongue.

Then he felt something warm and sticky between his fingers, a familiar feeling.

Nico looked down, his brows raised at the hot, crimson blood staining his fingers. The figure of a boy of fourteen or fifteen, barely older than he, stumbled and caught himself upon the railing leading down into the subway tunnel, one of his arms clutched tight against his midsection and the other holding a long, polished stick. He glanced back over his shoulder, a pair of emerald eyes framed by a mess of raven black hair pierced through a pair of thick-rimmed glasses covered in dirt.

Looking at something just over Nico's shoulder.

The son of Hades made to turn, his fingers brushed against the hilt of his Stygian blade.

The boy's free hand shot out and grabbed his wrist. His eyes transfixing Nico in place. "Don't," he hissed. "If you turn, they'll see and think you're helping me!"

A sharp cracking sound from somewhere behind him made the hair on the back of Nico's neck stand on end. The boy's eyes widened a fraction, he released Nico's hand and shuffled down the stairs as fast as he could, a dark trail down his left leg telling of his wound.

A pair of men let out curses, then pushed their way passed Nico and hurried down the stairs after the boy, each clenching sticks of their own in their fists.

They weren't monsters.

Monsters, to his knowledge, didn't go chasing after mortals with sticks. Or demigods, for that matter.

Tree limbs? That would've been more up their alley, and, for a moment, Nico wondered if they might have been skilled enough in controlling the mist to alter even his perception.

No, he told himself. I would feel something off. Even something like that.

Nico di Angelo skulked after them, drawing his blade slowly and gritting his teeth at the hiss of Stygian steel sliding free of its sheath. He heard one cry out a name, "Potter!"

He reached the third to last step just in time to see the boy, Potter, apparently, standing in an open space between the men and those girls who'd giggled at Nico moments prior. Potter turned slowly, the labor of his motion showing how he favored that left leg.

The speaker leveled his stick at Potter like he was pointing a gun. "Surrender the artifact," he demanded in his thick English accent. "The Dark Lord has grown tired of your insolence."

"But he is not without mercy," the other took up, like a dutiful subordinate. "Surrender it to us, lay down your wand, and, with your talent, he will consider you a viable candidate in his ranks with our recommendation."

Nico found himself reminded of some of Gaea's giant children, how they spoke of her in hushed reverence, and how she herself would promise the sky, moon, and stars if they would only just walk away and let her plans unfold.

His grip tightened. Potter was wounded, a boy at most only a year his senior. While Nico couldn't kill a mortal, he could certainly rescue one. But how to do it without startling the girls?

Potter spared him any such need to consider. He stumbled back and jerked his stick at one, his emerald eyes flashing dangerously as a loud bang echoed through the underground station.

The men raised their sticks and flicked them as if to parry a sword strike. A flash of blue-white light crackled against an invisible shield, the very air before them rippling beneath the force. Powerful, deadly.

Magic, he realized. But different than Lou Ellen and Hecate's children. Which means those aren't just sticks, they're wands.

Wizards, in a more classical sense. Like his old Mythomagic game.

Their counter spells came in rapid succession. Potter didn't bother trying to throw up his own shield, instead hurling himself sideways, bad leg and all, and swept his wand across his body like he were swinging a short sword. An arc of purple flames shot through the air at them, another pair of shields parried his blow. The first speaker thrust his wand at Potter and sent a thin bolt that would've put a hole through the boy's forehead if he hadn't ducked just in time.

It was right about that time Nico decided he'd seen enough and made his move.

Ducking low, he swiped his sword across the back of the second speaker's calves with a flick of his wrist. The man fell to his knees with a ragged gasp, eyes wide as he turned to have the hilt jabbed into his forehead. His eyes crossed before he slumped to the ground, unconscious.

His partner turned, his face turning an ugly shade of puce and wand raised. A curse, no doubt, on the tip of his tongue.

In his rage, he'd forgotten his surroundings. Namely, the young wizard rising from his knees, wand alight with his next spell.

Long enough that Potter could add a little flourish as he snapped, "Immobulous!"

A ripple of magic hit the man before he could alter course, and froze him in place, eyes wide and wand aimed at the ground.

Potter seized on his chance. He staggered to his feet, approaching in a clumsy, lumbering limp. With a growl of "Stupefy!" he shot a jet of red light at the man's chest and dropped him cold.

Blinking, Nico fixed the approaching boy with a critical stare. He knew magic, he'd seen it many times before, but not this sort.

And never practiced so openly outside Camp Halfblood or Jupiter that he recalled.

The boy heaved a sigh, exhausted from running and injury. "Thanks," he said with a weak smile. "Guess I did need your help after all."

Nico hummed an affirmation, his mind working rapidly. His eyes flitting at the men laying slumped on the floor, he looked into Potter's.

Emerald and raven hair. Why that combination?

He shook himself. He could lament the Fates playing games with him later. "You keep odd company, Potter," Nico mused with a pointed look at the boy's wounded leg. "And friendly, I see.:

"Call me a charmer," Potter replied with a pained smile. He offered his free hand, his palm stained red by a trail of blood from somewhere along his forearm. "Thanks again for the help. Harry Potter."

Nico eyed his hand a moment, but didn't accept it. "Nico di Angelo," he drawled. "You sound like you're a long way from home."

Harry's smile showed teeth. "Well, you see, summer holiday and all—"

"Dueling wizards is your summer holiday? In autumn, no less?"

"Er …"

"And bleeding all over Boston?" Nico arched a brow. "And my favorite jacket."

The boy had the grace to look sheepish. "Sorry about that. For what it's worth, I tripped and was trying not to drape myself across your back."

Again, he hummed. He cast a glance at those girls. They hadn't run.

Why hadn't they run? Or phoned the police, at least?

And why were they still watching? Hungrily, at that?

A lump of ice dropped into the pit of his stomach. It clicked at last. Nico positioned himself on Harry's left side, protecting the boy's wounded flank. "How fast can you move on that leg?"

"Er …" Harry blinked. "Not terribly, but I'm not crippled. Interrogation over already?"

"No." The girls began to drift closer, Nico's eyes narrowed. There were a few possibilities. None of them good. "Interrogation's on hold for now." He put his hand on Harry's shoulder and gave a light push. "Get topside. Now."

Unfortunately, Harry either didn't catch the urgency in his tone or he had the same problem most heroic types Nico had met suffered—an uncanny desire to stand in place and die spectacularly. The son of Hades put four drachma on the latter, mostly because the boy had the gall to try to turn and hobble forward so he could stand side by side with Nico.

And then he stared. "Er … you want us to run from a couple girls, mate?"

"No." Nico tensed. He couldn't draw in too much on his powers, not if he didn't want to risk caving in the subway. "Because those girls aren't humans."

"Aww! That little halfblood saw through us, girls!" the one who had been playing with her phone giggled, her eyes glittering in the darkness. She stalked toward them, her smile one of promise meant to lull the mind and dull senses. "Come here, darling," she crooned, the magic in her voice filling the air like a siren's song. "Such brave, handsome boys deserve a kiss, no?"

Nico felt her spell clouding his mind. He shook it off, grunting and blinking against the force of magic. Out of the corner of his eye, he saw Harry stiffen, his knee shift as if to take a step forward. He reached out and caught the boy by his injured arm and squeezed.

Hissing in pain, Harry jerked his arm out of Nico's grasp and glared. But he stayed where he was.

"Empousai," Nico warned. "Vampires with hypnotic voices."

"You're joking?" Harry wrinkled his nose. Were it not for the paleness in his features, it might have looked cute. At Nico's nod, he straightened up and readied his wand. "Thanks. Never thought Hermione shoving books in my face might save my life—though, maybe I should've by now."

"Not the time." Nico guided him back, back toward the stairwell. He needed to touch the shadows, but those empousai weren't going to just let him get to the only exit. His eyes flitted upward to the ceiling lights, then back just as quickly. "How much do you have left in you?"

"Huh?"

"How much more magic can you cast?"

The empousai licked their lips as fangs began to show. The mist fell, exposing razor sharp talons and mismatched legs.

Harry sucked in a sharp breath. "What the bloody—illusions now?"

"Magic," Nico hissed. "You. Casting. How much do you have left in you?"

Glancing from Nico to the girls and back again, Harry shook his head. "Enough for whatever you need."

Now, there was the sort of reply Nico was used to. Almost like he was back on the Argo II.

Out of the corner of his mouth, he murmured, "When I tell you, get the lights. All of them."

"Are you mad?" Harry lashed out with his arm and sent a bolt at the empousai's feet in warning. They didn't slow. "Fighting vampires in the dark?"

"Trust me." Nico grabbed him by the wrist and held fast. "Do it and then take a deep breath, and don't throw up on me."

Despite himself, Harry turned to level him with a quizzical look. "What?"

The empousai hissed and lunged for them, their eyes alight with a manic, hungry gleam.

Nico flicked the his blade in a wide arc and availed two of their heads in one swing and both dissolved into dust, the third danced to his left, just out of reach. "Cast! Now!"

With a wave of his wand, Harry snuffed every light in the station and shrouded them in darkness.

More than enough for Nico to summon forth the power to dissolve them in shadows and let the station disappear.

His intent had been to find some nice, quiet corner where he could ensure he was within his range to protect the retrieval party while he slowly drew information from his wounded compatriot. Unfortunately, though Nico had indeed improved greatly on his shadow traveling talents—much to his friends' chagrin once they'd learned the cost—he still held one or two rather pesky limitations.

That he needed to know exactly how many and what he was transporting? Normally, when he only had to worry about himself and wherever he wanted to go, Nico didn't have to worry about a thing.

But when a hungry empousa grabs onto the one passenger he wanted to bring along for the ride and did her very best to hold him in place so she could savor every drop of blood and piece of flesh rent from their bodies, one might understand how that could throw him just a bit off target.

So, instead of the nice, side street where they could easily duck into a building to wait her out while she stalked about and keep a weather eye on the streets in case the others came through with the new campers, Nico fell and landed hard on his back.

He could feel soft grass tickling the back of his neck, the stars above spinning as spots danced before his very eyes and the musty smell of clay. Blinking, Nico pushed himself to a seated position and shook his head. Where had they ended up?

A quick glance to his left presented him with a wide, empty swath of grass leading up to a short green wall and rows upon rows of empty seats. Nico could something that looked vaguely like a scoreboard and advertisements, a row of stadium lights, and, upon some sort of observation deck, the words "Fenway Park" written in red script upon a white background.

Oh, great. Nico grimaced. And there couldn't be a game going on for us to slip through the crowd at least.

A sharp hiss and yelp of surprise drew his attention to his left. There, laying on his back, his hands locked around the wrists of that last empousa and arms outstretched to keep both talon and fang from his skin. Harry twisted and turned, kicking out as best he could to help keep her weight from falling fast and buckling his elbows.

The empousa jerked his injured arm, drawing a pained cry and forcing is elbow to bend. Her talons sliced his skin from his wrist to his forearm, her eyes alight with sadistic glee.

She didn't realize she'd allowed him to turn his wand into her chest until he gasped, "Relashio!"

His wand let out a shriek, a jet of gray-blue light lit up the empousa's face and threw her twenty feet into the air, her arms and legs windmilling as if she hoped to fly.

She did not.

Her reunion with solid ground came with a most satisfying thud! But she didn't stay down. She rolled onto her belly, her eyes glowing and flaming hair whipped into a frenzy as her talons twisted and rent a large clump free of the hallowed sports ground. Then, she darted forward in a blur and swiped at Nico's face.

The son of Hades parried her claws with a deft turn of his sword, just in the nick of time. His blade's edge bit into her palms, beads of glittering gold ichor rolled down her wrists. Nico set his feet, gritting his teeth as she hissed and leaned in, baring her fangs.

"Sorry," he drawled. "But you're really just not my type." With a quick shift of his stance and hips, Nico twisted and drove the pommel of his sword across her face.

She staggered, wiping a hand across her face. "O positive," she hissed. "Pity. You're just mine."

To his left, Nico noticed Harry rising finally. The wizard aimed his wand, he only needed one chance, tired though he was.

Sword or wand. They had the advantage. They just needed to see who she went for first, and not miss the chance.

Her eyes betrayed her first. The empousa feinted toward Nico and lunged for the wizard, no doubt banking that she could take out the ranged fighter with ease and limit her opponents. Smart.

Though not quick enough.

Harry gave his wand a little swish and jab. Another bang rang out through the night air and thick ropes sprang forth like snakes lunging for their meal, forcing her to dive and alter course, instead swiping at Nico's neck.

He managed to block one hand, her other moved in a blue and buried her talons into his bicep. A pained cry tore from the back of his throat, his vision blurred. He saw her grin and jerk his sword out of his hand and ready to rip out his throat.

Then, there was a ripple through the air. The empousa had a split second to register something was amiss before her head suddenly jerked and a series of sickening cracks pierced the air. She slumped forward and dissolved in a shower of gold dust, just like her sisters.

Harry Potter lowered his wand, a cold look settled upon his features. He drew in a deep breath and held it a moment, his shoulders tensed, he squeezed his eyes shut and seemed to try to shake himself.

Nico let his shoulder relax. "First time?" he asked. "Killing a monster, I mean."

The boy shook his head. "A few. Never one I enjoy, especially the ones who look more mortal."

Must not deal with a lot then, Nico mused. Or he gets chased around by other mortals more than he does monsters, so he's skewed toward dealing with them. He brought his sword down and took the time to survey his counterpart again, taking note of his appearance.

While Nico wasn't exactly one for fashion, Harry didn't pull off any semblance of what one might call the "proper wizard" look at all, other than the wand clutched in his hand. His jeans were well-worn and held up by an old leather belt, his shoes looked as though he'd bought them at the dollar store, and his once white shirt beneath his gray hooded jacket had been stained crimson and gold with blood and ichor.

He looked like any other kid.

How many times have I thought that since leaving the hotel? Nico discreetly adjusted his grip on the hilt of his sword. "So," he began, picking up right where they'd left off, "summer holiday in autumn."

Through his pain and weariness, Harry had the grace to wince. "Don't suppose I could ask you to pretend too buy that one if anyone asks?"

Nico narrowed his eyes and stepped closer. "You owe me an explanation. I don't think you're in any position to ask anything of me right now."

"Do I?" Harry's smile became strained. He took a step back, his eyes flitting to the blade of Nico's Stygian sword. "Something to do with that half-blood business?"

Trying to increase distance and at least give himself a chance to duck if he needed. Smart. If he weren't exhausted and injured.

"You could say that." Nico followed, his motions as deliberate as a predator stalking its prey. "Mortal wizards and monsters, and drawn off-course because of you. What in Hades's name did you steal that saw you running through Boston like that?"

"Steal? Me?" His emerald eyes flitted down and away.

Not a good liar at all.

The son of Hades tightened his grip. "What artifact were they after?" he asked in a low, dangerous tone. "And who is this Dark Lord who wants it badly enough to send two grown wizards after the likes of you?"

Something flashed across Harry Potter's eyes. Irritation? Pride? Or perhaps just some sort of fire he kept hidden behind that crooked smile and pisspoor alibi.

"I like to think of myself as a professional nuisance for their master," Harry replied. "That said, I've got a bit of a schedule to keep, so … how about a mulligan on the explanation?" His wand hand twitched, the tip raising just slightly.

Nico's blade came up, level with the wand. "An inch higher and I split it in two," he warned. "And you'll be face down in the grass telling me what I want to know."

Nodding, Harry made a show of lowering hid wand to his side. "Fair enough. I won't point a wand at you. Although—" his eyes shone with mischief "—I feel I should warn you, I know something you don't."

Alarm bells rang in Nico's head. He brought his blade up beneath Harry's chin and forced him to tilt it up. Something about the way moonlight glinted off those dingy glasses gave him a split second's pause.

That split second was all Harry needed.

The wizard smirked. "The wand only helps a little," he said as he turned up his empty hand and opened his fingers to reveal a globe of light the size of a baseball.

Nico made the mistake of looking down at it, just long enough to get a face-full of light and sound as it exploded in Harry's palm. A flashbang spell.

The son of Hades staggered back and threw his opposite forearm across his eyes, his ears ringing like the shrill whistle of a train. By the time it all stopped, by the time his vision returned and spots stopped dancing before his eyes, Nico di Angelo found himself alone in the middle of Fenway Park.

Alone, without a sign of Harry Potter's flight.

When the grounds crew arrived for their morning shift, they were perplexed by the jagged tears cutting from the infield to the pitcher's mound, as if a small, localized earthquake had carved out a chunk of one of baseball's most hallowed fields. The patches of dead, footprint-shaped patches leading from just past second base to the dugouts was almost mundane by comparison.

The lingering chill down their spines gave the distinct feeling of someone, something powerful present.

And it was angry.