A/N: hi guys! Just wanted to clear up something from the previous chapter. People seemed to be confused about who it was about, so I just wanted to say that it is very safe to assume all these stories will be Castle/Beckett centred, unless stated otherwise.

Thank you for your continued support : )

Twenty-one

"I need you to tell me that my daughter turning twenty-one isn't anything to worry about." He strode into the bullpen, placing her usual coffee order on her desk.

She smirked, keeping her focus on the cup in front of her. She contemplated messing with him, telling him completely fictional stories of wild behaviour and her 'good girl gone bad' phase. It was always fun to tease him when it came to his completely irrational concern that hitting certain milestones in life would suddenly flip some metaphorical switch on his daughters personality.

"What are you doing here, Castle? Don't you have a party to organise?"

"What were you like at twenty-one?" He pushed, slumping down into his chair by her desk, not at all reassured by her avoidance.

He didn't know why he thought stories of her younger years would help... her and Alexis weren't exactly alike in any way. But if he could use his daughter as an excuse - a mask for his own curiosity - then why wouldn't he? He wanted to know more about Beckett... everything about Beckett. As much as she would allow, anyway. But when her smile faded and her focus on the cup on her hands became all the more determined, he thought perhaps he didn't want to know.

"It wasn't a good year for me, Castle." She offered, before bringing the cup to her lips. In this moment, she just needed something - anything - to hide herself away from his burning gaze. She hated how intense he was when he studied her responses. Even more so, she hated how it made her feel... insecure. Like he could see her vulnerabilities, even when she was trying her hardest to hide them.

"Of course." He hung his head, realising his mistake. A major life milestone - possibly one of the first 'big ones' - without her mother. "I'm sorry."

His reply took her by surprise. Boundaries were never his strength... setting them or respecting them. She expected him to pry. To push her for more. But he didn't.

"Alexis is a good kid."

"Not a kid anymore." He reminded her.

"Right." She nodded slowly as she realised the true issue. His baby wasn't a little kid anymore. She was a woman. An independent, intelligent woman. And she didn't need him anymore. "Always your little girl, though. Right?"

"Yeah." A soft, sad chuckle slipped from his lips. "Don't know if she'd agree."

She rolled her chair toward him, placing her hand over his. His eyes met hers, holding the same intensity as before.

"Trust me, Castle. Your little girl is still there. She's busier now... more independent. But she's there. And she'll always need her dad." She offered a reassuring smile and stroked her thumb along his knuckles.

"Thank you." He flipped his hand, grabbing hers and bringing it to his mouth, placing a quick kiss against it. "I think I needed that."

She smiled, bringing her hand down to rest on her thigh, hidden from those around her. "You're welcome."

"I have a cake to pick up. But I'll see you tonight?"

She nodded her confirmation.

"Perfect." He beamed, and took his leave. She watched, smile plastered on her face, as he left.

"Aww, cute." She heard the mocking voices from the break room. She turned to see Ryan and Esposito leaning casually against the door frame, smirking and pulling 'kissey faces' at each other.

"Shut up." She balled up a scrap piece of paper and tossed it at them, somehow hitting them both.