Chapter One: Boundaries.

Kate Beckett was in serious trouble. Stubborn as she was, she could never admit the previous statement unless she was absolutely sure. So, she thought again, I am in serious trouble.

"Beckett?" Castle's voice brought her back to reality; the precinct, the smell of stale coffee, old paper, and the faint tang of Castle's cologne. "You okay?" His blue eyes were concerned, but Beckett could see the undercurrent of adoration in them. She gave him a small nod, and as he turned his eyes to his phone, she let her gaze wander.

She drank him in, from the playful quirk of his mouth, to his perfectly crisp navy blue shirt, to his gunmetal grey jacket and pants, down to his tasteful shoes and back up, all the way to the slope of his nose to his gently tousled hair. His fingers fiddled with the phone in front of him, probably playing Angry Birds, and Beckett's hand twitched with the undesirable urge to be that phone.

"You're staring at me," he observed casually, his eyes on the screen. "You're right. It is creepy."

Beckett blushed magnificently, and Castle struggled not to smile. "Fine, then I won't tell you that you have something on your face," she replied teasingly.

His hand flew to his cheek. "Where?" He asked, alarmed. Beckett, blush officially banished, reached up her right hand and lightly brushed an eyelash off his cheekbone. Her hand lingered there, caressing the vague stubble on his jaw, her traitorous heart thundering in her chest.

"Kate," his voice was low, barely over a whisper. Her eyes lowered involuntarily to his lips; she was dangerously close to the precipice of doing something incredibly stupid, and the sheer inevitability of it almost floored her. Her eyelashes fluttered, and she met his eyes again. She felt something closing in on her throat, the background noise of the precinct fading away. His hand caught hers, and there were those torturous circles on the top of her hand again, maddeningly slow, deliciously so. Her eyes flickered down to their joined hands and returned almost immediately to his fathomless eyes. She opened her mouth to speak –

And the phone rang, jarring the both of them from their cloud. Beckett reached for her phone, leaving one of her shaking hands next to Castle's. "Beckett," she choked out. The color slowly drained from her flushed face as she listened, and the hand next to Castle's tightened into a fist. "You're sure." It was not a question, but a forced statement, through her teeth. "Be right there." The phone was not placed down, but slammed. It lay there, silent in its cradle, as if it would never dare to ring again.

Castle watched her head drop to her hands, fingers tangled in her hair. He counted slowly to ten before he dared speak. "Beckett?" he asked tentatively.

He saw her stiffen, her hands still shaking. "Go home, Castle," she answered, her voice strained.

"Beckett, please tell me what happened."

Her head did not rise. "Go home, Castle. Now."

Finally, he sighed. "No." She exhaled through her teeth, and inhaled sharply, as if she was in pain.

"Go home, or you won't come back," she snapped.

He leaned back in his chair, shocked. She never threatened their partnership like that, at least not lately. He thought she had seen him as indispensable now, that she wanted him by her side, if not for entertainment, then for some deeper reason that made him too nervous and giddy to even think about. It seemed the boundaries, the ones they had stepped over just a few moments before, had been redrawn, and precious ground he had gained was gone. He sighed heavily, an ache in his chest, and stood. He placed a comforting hand on her shoulder, and withdrew it when she jumped.

"You know you can tell me anything."

She stayed silent.

He nodded, unsurprised. "Call me later."

"Victim, Josh Davidson, age 31, COD, single gunshot wound to the head," Lanie, mercifully, kept Josh's face covered, but his skin was so white, tinged with blue, and the blood under his head so red that Beckett could barely stop the bile that was rising in her throat.

Lanie paused. "Honey, do you need a moment?" Ryan and Esposito, off processing the scene and searching for security cameras, respectfully kept their distance. Beckett shook her head, swallowing past the hysteria in her throat. "Where's Castle? I find it hard to believe he would let you come here alone."

Finally she spoke, and her voice was monotonous, unfeeling. "I sent him home." Lanie's hand stopped moving on her clipboard. "Don't say a word."

The reply was quiet and curt. "I should smack you."

Beckett kneeled by the body, checking for anything out of the ordinary. "I couldn't have him here," she explained quietly. "Not like this."

Lanie nodded like she understood, but Beckett knew she didn't. She could not have Castle here, not because she was afraid he would see her as the mess she was, but because she was afraid of what her reaction to him would be, especially after what she had done this morning. She had blurred those boundary lines almost beyond recognition, and she was afraid of what comfort she might seek, comfort she would regret later. She was even more afraid of pushing him even farther away than she already had.

Lanie passed her clipboard to Alexis, who kept her eyes averted from the detective. Beckett looked away, feeling tears sting her eyes. Her relationship with Josh, though over, had not been a bad one. Their breakup had been amicable enough, and they had kept in general contact. She had spoken to him just a few nights ago, about his latest trip to Haiti. There was one small detail, one that even Lanie did not want to point out, that was stabbing her in the heart.

Josh's dead body was lying in the same alley where her mother was killed. Just bringing the thought to the forefront of her brain cut off the ability to breathe, and she found herself rooted to the ground as thought after terrifying thought battered her senseless.

Josh is dead.

In this same alley.

Where her mother died.

Oh God, her mother is dead.

Why is she here?

Where's Castle?

"No prints, no security tapes, no nothing," Esposito spat, shoving his notebook into his pocket. "No one saw a thing."

Ryan, ever-helpful, added, "This is beginning to look more and more like a professional hit."

Beckett didn't even blink. She gave her boys a brief nod and went back to her car, calling back to Lanie that she would meet her at the station, and sped off. The tears came fast and hot on her cheeks, dripping off her chin onto her lap as she drove. She dried her eyes on her sleeve, fixed her hair, and entered the bullpen dry eyed and stone faced.

And came to a screeching halt.

Castle was beside her desk, leaving a note by a huge cup of coffee. He looked up, his eyes finding hers like a magnet, and he looked shamed.

"I thought I told you to go home," she said quietly.

He looked down at his shoes. "Alexis called me. I was just leaving you coffee and a note," he held it out to her, and she took it carefully.

"You can always talk to me if you need to. Always."

Tears welled up in her eyes, and she pushed it back, keeping her eyes on the note. "Thank you Castle, but I can handle this on my own."

"I never said you couldn't," her eyes, misty or not, slammed up to his, and he gave her a soft smile. "I'm just saying you don't have to."

She could see it again, the 'I love you' shining just below the surface of his eyes, and she felt the words in her throat again. But she couldn't say it, not here, not now, and probably not ever. She broke the eye contact and grabbed the coffee he left her, and glanced back up, looking for strength in his eyes. Heaving a breath, she closed her eyes and called for Esposito.

"Pull my mother's murder file," she said quietly. "Be silent about it."

"Got it."

Castle's mouth was open. "Wait, what is this about?"

"Just a hunch," she turned to Ryan, who looked as awestruck as Castle. "Bring me phone records, financials, job schedule, everything. Now."

A shrill siren made her flinch, and she glared at Castle, who gave her an apologetic look while pulling out his phone. It was restricted. He had expected this call.

"Hello?"

"Make her stop," the man, the one who was trying to keep Beckett safe, or at least that's what he claimed, was calling to take a toll on his patience and sanity again. "Make her stop, or she will die."

"I can't make her stop, this was her ex-boyfriend," he whispered fiercely. "Whoever these people are must be slipping up, because they're leading her right back to her mother's case." He turned his back to the bullpen, and cupped his hand over the speaker. "What is going on here? Why won't they just leave her alone?"

The man's voice lost all emotion. "Do you want to keep her safe?"

Castle didn't even hesitate. "Of course."

"Then make her stop, or I promise you, she will die. Good day, Mr. Castle."

"Wait!" he called, and glanced over his shoulder, and gave Beckett a 'nothing's wrong' look. "Look, I have money, I have influence. What do you want? I'll do anything."

The man was stern, unrelenting. "Then keep her away from this case."

The phone went dead, Castle looked up into the eyes of Katherine Beckett, and was at a loss. What could he possibly do? Lie to her again, continuously, until she found him out and left him forever? Or tell her the truth, and put the crosshairs on her again. His mind brought up the feeling of Beckett's breath leaving her body for good, and he remembered the look on her face when she found out he was looking into her mother's case in the first place.

He mentally placed these next to each other, and looked up. Esposito, Ryan, and Gates were all milling around the bullpen. He struggled.

"Castle, what's wrong?" She asked, holding his coffee and placing the sticky note on the side. "What happened?" She looked so concerned that he almost broke right then and there. He wanted to sweep her into a hug and never let her go.

He loved her, that much was incredibly certain. He loved her uncontrollably, painfully, so much that it made him hurt and gave him immeasurable comfort at the same time. All those songs she was talking about made sense, and he was sure that they had to for her too. But how long would they make sense to her if she found out what he was hiding? He couldn't stand speaking a different language to her again, one she did not want to understand. He swallowed, and made his decision.

He stared into her eyes, so long that she wrinkled her nose uncomfortably, and smiled a grim smile. He was walking right to his execution, and possibly even hers too. "Beckett, I need to talk to you about something important, can you come with me?"