Author's Note: Thank you all for your patience and understanding; work has been beyond hectic for the past month, but now that all of that is behind, I can get back to updating this - and my other fics - much more frequently. Thank you all for your support, and please, reviews are great!

The Twelfth…

Richard Castle had barely slept the night before, a combination of working on his manuscript for Heat Wave and the fact that he didn't know what to make of his conversation two nights ago with Angel. The writer felt as though he was privy to information he didn't need to know; something told Castle that if Detective Beckett wanted him to know about her tragic past, she would say so.

And considering the fact that he was trying to be on his best behavior at the precinct – which, admittedly, was difficult for him – harboring this secret was tough. Adding the fact that the P.I. suspected Captain Montgomery of shady dealings didn't help matters.

What was Castle supposed to do with this information? Tell Beckett? Let her know that he knew stuff he honestly had no business knowing? Accuse the man she looked up to professionally of possible corruption based on the word of an ex-lover who also happened to be a vampire?

No…for once in Castle's life, discretion was the better part of valor. Still, as Castle strode into the bullpen, two cup of coffee in-hand, he couldn't help but glance into the glass box that was Montgomery's office, watching him as he jotted something onto a pad of paper with the phone cradled between his ear and shoulder.

Once he got to Beckett's desk, Castle handed her one of the cups before lowering himself into the chair beside her desk. She smiled her thanks; it was a small smile, once Castle would've missed if he'd blinked, but it was something. He returned the smile, but it disappeared the second his eyes caught the murder board.

"Uh, Beckett?"

"Allison Tisdale," she began after taking a sip of her coffee, leaning back in her chair. "She was a social worker."

"Right," he pursed his lips and nodded once. "But I'm guessing the fact that she was a social worker isn't why you called five times this morning."

"No." Kate sighed. "No, it's not."

Castle stood and approached the white dry-erase board, studying the crime scene photos that sent a chill down his spine unlike anything he'd seen in the brief time he'd been shadowing Detective Beckett. Not even the creature he saw Kate and Faith fighting the week before made his skin crawl the way these photos did.

"Straight out of Flowers For Your Grave," he muttered and shook his head.

"And she's not the only one," Kate joined him by the murder board, slapping another crime scene photo to the surface – a man splayed out on the floor, dead, surrounded by a crudely drawn pentagram. "Marvin Fisk, attorney. I didn't think much of the placement of the body when we caught the case, but after Tisdale…"

Castle nodded, swallowing the bile rising in his throat. "Hell Hath No Fury."

Kate studied Castle as he studied the crime scenes photos, a deep crease forming on his forehead, his brows scrunching together in a mixture of confusion and disgust. He set the cup of coffee in his hand aside, having lost his taste for it, before grabbing a photo of Tisdale's face, covered in the giant sunflowers, and shaking his head.

"What, no quip?"

Castle shot a glare Kate's way. "Please. I may be a jackass, but I'm not heartless."

Averting her gaze, Kate cleared her throat and grabbed a manila folder that had been lying on her desk. "Sorry," she muttered before opening the file. "Ryan and Esposito have been running down both Fisk and Tisdale, seeing if they had any connection. So far, nothing's popped, but I'm not so sure the victims are the story here."

"The victims are always the story," Castle countered. "But they're not always the only story. It's clear we're dealing with a fan here."

"Yeah, a clearly deranged fan."

"I wouldn't call you deranged, Detective."

Kate blinked, putting the folder back on her desk. "What?"

"Come on, Detective," Castle couldn't help the smirk forming. "The fact that you read the Derrick Storm books is one thing. But…Flowers For Your Grave? Hell Hath No Fury? Only hardcore Castle groupies know about those."

Narrowing her eyes and biting her lip – because there was the insufferable man-child she'd been saddled with – Kate folded her arms across her chest and shook her head. "Castle, whoever did this is a deranged fan. And history tells us that in cases like this, the killer reaches out to the object of their obsession. Have you received any creepy fan mail recently?"

Castle shrugged. "I get creepy fan mail all the time. Occupational hazard."

Kate rolled her eyes. "Do you have access to any of it?"

"Let me make a phone call," Castle said. "All the really weird ones go to my publisher to be vetted. Nine times out of ten, it's nothing."

Kate returned to her desk, lowering herself into her seat. "Well, consider this the tenth."

Returning to his own seat, Castle grabbed for his cup of coffee again, taking a sip. "So," he began, "you and your P.I. friend. How does that work, exactly? Does he read my books to you while you style and gel his hair? Ooh, bonus points if he reads to you while you're waiting to stake a freshly-risen vampire."

Kate arched a disbelieving brow, dropping her pen. "You know Angel."

"Mm." Another sip of coffee. "Not like you."

The arched brow only arched more, and Kate couldn't help the sideways grin on her face. "Is this you being jealous?" The detective huffed a laugh before Castle could respond. "Really, Castle? The playboy writer is jealous of one of my exes?"

"Not jealous," Castle protested – perhaps a little too vehemently for his liking. "Angel's…interesting. A lot like you. Square jaw, taciturn, not big on fun. I can see why it didn't work, though."

"Really."

"Yeah, he's like the male you."

"And that's a bad thing."

"There was no balance," Castle argued with a shrug. "You were too much alike. Yin needs yang, not another yin. Yin yang is harmony. Yin yin is a panda."

Though annoyed, Kate was also somewhat amused. It was a strange dichotomy she'd experienced almost every day since Castle started shadowing her – this simultaneous desire to strangle him while trying not to laugh – because laughing would only feed his ego and encourage him further.

Then again, annoyance didn't deter him so Kate was pretty much damned if she did and damned if she didn't.

"Funny," she quipped, "coming from the guy who's been married twice."

The zinger didn't have its desired effect, and Castle offered her a smug grin and a shrug. "Been perusing the personal section of the Richard Castle website, have we?"

"Just get me those letters," she said with more bite than Castle expected. "And so help me, if this new book of yours inspires a copycat murderer, then I will give you a first-hand demonstration of my service piece."

Castle's loft…

Going through the fanmail had been exhausting – both because of the hours it took to scan through every letter and the fact that some of the letters were downright disturbing. Based on that alone, Castle wondered how many sickos were reading his books and going about trying to kill people.

It wasn't enough to make him stop writing, but it did make him grab for the scotch pretty much as soon as dinner ended. Fortunately for Castle, he had company – not in the form of the hot, no-nonsense detective, but in the form of a fun-loving monster hunter who sported a tattoo on her right arm.

The look on Alexis' face when she told Castle that Faith was here was amusing; it was almost a cross between the look she would give her father after a one-night stand and the glare she shot his way the day Meredith swooped into town to take her out for lunch – in Paris.

"Cute kid," Faith said as she plopped herself down in one of the chairs across from Castle's desk. "Never woulda pegged you for Mr. Mom, though."

A smirk played across Castle's features, even as he downed his drink. Setting the glass aside, he returned to his desk, grunting as he lowered himself into his chair. Castle wasn't old – really, he wasn't – but his knees occasionally liked to try reminding him otherwise.

Once he was comfortable, and stealing a quick glance at his laptop, where the unfinished manuscript for Heat Wave taunted him, Castle leaned back and regarded Faith with a quirked brow. Then, pouring himself another glass of scotch, he pointed.

"So what's your deal?" He asked before downing his glass. "What's your interest in Beckett?"

"Oooooh, no," Faith smirked, reaching for the bottle of scotch and taking a swig directly from it. "That's a Giles question."

"Believe me, I asked." The writer sighed. "He's less forthcoming than the CIA."

"G-man's not big of specifics," Faith shrugged, cracking her knuckles. "But she's on Wolfram & Hart's radar, and that rings all sorts of alarms with the Council."

Castle frowned and sat up a little straighter. "Wolfram & Hart? The law firm?"

"Right, the law firm." Faith smirked. "The same way Angel's just a P.I."

"Yeah, about him…" Castle rose from his chair, setting the empty glass on his desk before crossing to the empty chair beside Faith. The Slayer's quip about the law firm tugged on his latent curiosity, but for the moment, Castle decided to leave that mystery for another time. It was unusual for him, but his conversation with Angel the other night had practically gnawed at him ever since.

"Did you know he and Beckett used to be a thing?"

"Kinda figured," Faith shrugged. "His scowl is less scowl-y when she's around."

"Let me guess," Castle leaned in closer, his eyebrows waggling the way they always did when he was unraveling a tale, "things are going great, the monster hunter and the private eye, until…oops! She finds out he's undead. The very thing she's sworn to kill. A Slayer and a vampire together…as plot twists go, it doesn't suck."

Faith watched the writer ramble on, her brows arched in amusement. He really was like a nine-year-old on a sugar rush, wasn't he? She shook her head and suppressed the smirk that tugged on her lips.

"Or maybe…" Castle's features darkened. "Was it Angelus?"

All amusement left Faith's features, her heart skipping a beat as her hand instinctively went to the side of her neck. For the most part, the scars had healed, but every so often, she could still feel the pull of skin, the raised flesh reminding her of just how close she had come to her own demise.

"What do you know about Angelus?" Faith asked, paler than usual.

Castle shrugged and shook his head. "Not much, just…how bad was this guy?"

Bolting out of her chair, Faith leaned down to press a hand to Castle's shoulder. She glared at him with dark eyes, darker than usual, colored by a fear he had yet to see in the woman. Brown locks framed her face, giving her a rather ominous look.

"Trust me when I say you don't wanna know," she whispered.

Castle watched as Faith crossed over to where his office led into the living room, his mouth agape. "You've seen Angelus, haven't you?"

Faith stopped at the doorway, turning to regard the writer again. Truth was, she kind of liked being around Castle. He was fun, in his own unique way, and based on what she knew of Detective Beckett, Faith knew he could be good for her under the right circumstances. But something told her that wouldn't be the case, especially if Wolfram & Hart was involved and if Castle insisted on poking his nose into things he really didn't need to be dabbling in.

"Rick," Faith shook her head, "some mysteries are better left unsolved."