"So, you definitely confirm that the victim was killed by…?"

She crouched low on the alleyway, her boots sticking to wet asphalt, making sure to keep her grey greatcoat clear of the slush and dirty snow on the ground. New York in winter was no picnic, and solving a murder in winter even less so. Gloved hands prodded at the unnaturally stiff, almost stone-like flesh.

Lanie looked up at her as she trailed off, not even wanting to voice the thought, but there wasn't much sympathy there from her friend.

"Yes, Beckett. Unfortunately for you, the means of death was definitely magical. All forensic evidence, including the simple skill of observation, where the man has basically turned into a statue, confirms it. Call your boyfriend."

"He's not my boyfriend." She ground tersely before she stalked away. Esposito and Ryan were gathering statements from any potential witnesses and the uniforms who had been first on the scene, but she didn't hold out much hope there.

Instead she hit one name on her speed-dial and prepared to call in Richard Castle, the NYPD's consultant mage and ruggedly handsome pain-in-the-ass.

He didn't look like a mage. Or a wizard, or whatever. No funky robe, no pointy hat, no staff, no wand. Just those baby blue eyes, a charming smile, shoulders that filled out his worn leather jacket and incessant need to flirt with her.

Oh, and the fact he was a bona fide magician.

"Oh Detective, always a pleasure to see you." He strode into the alleyway about half-an-hour later, his hair so adorably mussed that she formed fists so she wouldn't be tempted to run her fingers through it and comb it down.

"Hope I wasn't interrupting some serious magical research." She tried to keep the sarcasm out of her voice. She failed.

"Never fear, Beckett. I always look forward to an interruption in your dulcet tones, no matter what I'm doing." He quirks his eyebrows at her, maddeningly. "You're sort of my muse you know?"

"What, have you taken up writing poetry as a hobby?"

"Ahh, the withering Beckett putdown. I've missed it these past few weeks. No, no. There is a reason magic is called The Art, you know. It is as much art as science, or anything else. And you, Detective, have certainly proved…" He trails off for a second.

She hates herself for it, but she waits for him to finish the sentence with a slightly bated breath as they stroll up to the body.

"…inspiring."

"Yeah, well, put some of that inspiration to work here and tell me about the victim and the magic used on him." She tries to keep her tone as dry as possible, and from the puppy dog eyes he gives her, she's successful. Good.

They're at the body now, and she hands him a pair of latex gloves, which he puts on with moue of disapproval. According to Castle, he needs to touch the bodies to get the best sense of the magical imprints leftover from spells, but forensics still trumps such concerns.

"This is…old. A really old spell. Maybe even a curse."

She crouches down alongside him as his blue-encased fingers run over the stony torso, prodding and pushing at regular intervals.

He mutters Latin under his breath, and suddenly there is a pale pinkish-red aura, or light, or something, encasing the body. She risks a quick glance at his face, his breathing even and calm, eyes narrowed in concentration.

He mutters again, and the light goes out.

"It's really creepy when you do that, Castle."

Lanie hovers a few feet away from the body, coming back in closer now that he's done.

"I need to further study of the body, but it'll be better in a controlled, sterile environment like the morgue."

His knees flex as he stands up again, and her eyes flicker unbidden to the curve of his rear, the strong thighs hiding under fitted jeans.

"Well, I'm not gonna break my scalpels on this, so you come down quicksmart and do your thing."

He sketches a salute at her in acknowledgement, and steps away from the body. She trails after him. Unlike her best friend, she doesn't feel creeped out when he uses his powers. If anything, she admires him more. The jokey playboy persona is discarded in those moments, and she can see the will and the power and the intellect it usually hides come out instead.

It's terrifyingly attractive.

"It's Greek. Ancient Greek, I think. I don't know, I'll have to do some research and get back to you in more detail. And conduct that more detailed examination at the morgue."

"Well, we think we've got an ID. Ryan found a wallet in a dumpster one block over. We'll start looking at the usual things- phone records, financials, girlfriend, family…"

"Got a name?"

"Daniel Schilling. German driver's license. Ring a bell? Met him at a coven?"

This time it's her turn to serve her with a withering stare, and she grins at the rise she gets out of him.

"Never heard of him, actually. And we don't hold covens."

He's quiet on the drive back to the station in her cruiser, tapping away on his phone.

"You know, I always expect you to be more of a Luddite instead of playing constantly with new toys."

"Ahh Beckett, classic mistake. We're not all wizened fuddy-duddies with beards, complaining about the good old days you know. I'm texting Alexis back, she's visiting her mother in California."

They drift back into silence, companionable really. Almost comfortable.

She allows herself to reminisce back to the case that had brought them together. She'd known of him, of course. Even in a huge metropolis like New York, there were only a few mages who'd made their identities known. Most people viewed them with distrust, even fear. Most kept their powers a secret. A few, like Castle went public. He was charming and handsome. He wrote for the Times and appeared as an expert on CNN panels. He was in many ways the human face of a great unknown.

She'd admired him for years, and never thought their paths would cross beyond that one time she'd gone to one of his public lectures on demystifying magic.

Not till the Larsson case. The one that had brought together.

She could still vividly recall the charnel-house smell of the hotel room, the seared flesh that had both been splattered around the walls and stuck to the bones, the way that even she'd had to pause for a moment to control her gag reflex, the way Ryan's face had gone green, Esposito had visibly shivered, experience homicide detective each and every one of them.

The word from Lanie had been unequivocal. The cause of death had to be magic. No explosive, no gun, nothing else could explain what had been done to the body. Magic's existence had been this distant force in her life till then, as applicable to her work as high-energy quantum physics. Not any longer. The first place to go had been to the most publicly-known mage.

He'd been trouble ever since their first sparring session in the interrogation room. Charming, handsome, intelligent, cocky, well-connected, he was an utter nightmare. An utter nightmare who'd insinuated himself into her case, and then onto her squad.

An utter nightmare who turned out to be a decent detective, and more surprisingly, a decent man. More than decent- steadfast, honourable, honest, protective, a great father…

She squeezed off that thought train before it could really get going. But it was too late, because her subconscious was auditioning him for the role of "husband" and "father of her children" in her mind far too often. Often enough that she was coming to like the thought.

Of course not every case they dealt with magical. There were maybe a dozen or so of those a year, and they inevitably came to her ("Beckett, she likes the freaky ones" was now a running a joke in the force. Her 100% case closure rate in so-called freaky cases was not), but even when it was mundane old murder, he still proved insightful, that problem-solving, outside-the-box thinking brain of his chipping in with plenty of case-breaking insights.

"I was wrong. It's not a spell, anyway. I think it's a medusa."

"Castle…"

"What? Beckett, you've watched me capture a rogue werewolf, duel another mage and reverse a curse that was leaving a woman's ex-boyfriends with the bubonic plague all over the city. You're gonna play skeptic with the existence of medusa?"

She sighed, massaging her forehead with her fingers. Ryan and Esposito's hard yards on the victim's financials and phone records had yielded nothing, and her own afternoon re-tracing Schilling's steps in the last 24 hours had been just as fruitless. And now this.

"C'mon." His voice is soothing now, gentle. "I'll make you a coffee."

Gently he tugs her towards the breakroom. There was a time she would've dislocated his wrist for that (or maybe not, given that he'd threatened the last perp who'd laid a hand on him with being transformed into a frog…), but now she just followed reluctantly, waiting at the table while he worked the machine he'd insisted on buying ("If I'm gonna work here, Beckett, I need coffee that tastes better than monkey pee in battery acid. You don't want to be around a mage firing off spells while half-asleep. Trust me"), till a foaming, delicious mug of latte appeared before her.

She took a deep breath, followed by a sip. Delicious as ever. Dammit, she might just propose on the spot if he made her coffee every morning like this.

"You cheat and magically make your coffee better, don't you Castle?"

"Nope, Scout's honour." He grins, holding up his fingers, but she recognises that tone in his voice.

She gives him The Look. He's a frequent recipient of it by now, in fact there's probably a Castle-specific version.

"OK, OK, I wasn't a scout. But the coffee is all-natural."

She takes another sip, savouring the aroma and taste, before resigning herself to the inevitable.

"OK, tell me about the medusa."

She can't help but smile at the slightly pupp-dog way he smiles at the question, and listens intently to the explanation he launches into about young medusa and their habits.

He's right, in the end. They corner the killer in her hide-out, wear reflective gear and eye-pieces (Castle had insisted on leading the way, as he was the expert on the threat- it had rankled but she'd reluctantly been forced to agree).

Confronted with the evidence and the motive (Schilling had enticed her into his criminal plans, intending to use her as an assassin, and then double-crossed her), she'd spit out angry Greek curses at Castle specifically, who'd calmly shrugged them off, not batting an eyelid at the hissing snakes either.

"After two marriages, and ex-wives like the ones I've had, you sort of get used to that kind of thing." He'd wisecracked as they gingerly loaded her onto the van, her eyes tightly covered.

She eyed the van as it drove away, escorted by two squad cars, as he came up behind her, undoing that personalised bullet-proof vest ("MAGE" emblazoned across it, of course) that he wore over that dark blue shirt that went very well with his eyes…

"Penny for your thoughts, detective?"

"Just thinking how they never really covered anti-medusa tactics at the academy."

"Hey you never know, you might get to give that lecture."

"Just not what I expected to be doing when I joined homicide, I suppose." She shrugs, trying for nonchalant and worldly, but the warm smile that appears on his face means she hasn't managed to hide her thrilling fascination with the world he's brought her into.

"Well, some things never change detective, never fear. Remy's? I really could do with one of those burgers…"

"…and those shakes. Oh, why not?"

They walk away down the street a few minutes later, side-by-side, a detective and her mage. Ready to fight monsters and warlocks another day.

A/N: This is the second effort in my series to imagine Castle in different settings and AUs (check out my rockstar AU 'In Tune', if you haven't yet). This police procedural urban fantasy AU setting was at least partially inspired by the Harry Dresden and Rivers of London series, and I really like the idea of Beckett the skeptic wrestling with a world full of tangible, actual magic. Anyway, let me know what you thought, reviews are always appreciated.