Castle had known that after the summer there was a chance she would see other people, he had even attempted to mentally brace himself for it, but nothing could prepare him to see her walk away from him with someone else. Twice. Especially not in the same week.
First, it was her former training officer. The older man had seemed like a goldmine in the beginning, spilling stories about Officer Beckett from back in the day and showing Castle adorable pictures of her in her uniform, but then his time in the precinct turned from convenient to treacherous, and Rick had watched Kate's eyes fill with the betrayal Michael Royce had bestowed upon her, the ache of being used consuming her face for the rest of their case.
But hearing her profess her love to the other man, despite the feelings being from the past - that rattled him in a way he hadn't expected. She had played it off as an act to get a trace on Royce once the call ended, but he knew the raw quality of her voice, knew it was more than acting, and even as she walked away, he caught just the briefest glimpse of her face crumbling.
He followed her down the hallway, keeping his distance just long enough to catch up to her before she escaped into the privacy of the restroom. "Kate."
"Don't," she called over her shoulder once she realized he was trailing behind her into the women's bathroom. "Just go wait outside by the car, I'll be there in a second."
She had gone for drinks with her former training officer the night before and Castle had prickled with jealousy as he had watched the two walk away together when he wanted to be the only man she strolled out of the precinct with at the end of the day. He hadn't viewed Michael Royce as a threat, but had definitely picked up on the subtle hints of chemistry between the older man and Kate since he had shown up, knew more than a teacher/student relationship lay between them.
She had loved him once. All she had done on that phone call was confirm his suspicions.
"Kate," he sighed, standing patiently just inside the bathroom door as the gripped the edges of the countertop, staring down into the porcelain curve of the sink with pursed lips and hunched shoulders.
"What, Castle? What do you want me to say?" she muttered.
"You don't have to say anything, just…" He took a tentative step closer. "You weren't lying, when you spoke with Royce just now."
"No, for the most part, I wasn't. So what?" she snapped, turning on him with that defensive fire blazing in her eyes burning away the remnants of forming moisture. "Is that so hard to believe?"
"No," he murmured calmly, catching her wrist, smoothing his thumb in circles under the soft fabric of her cardigan and over the throbbing cadence of her pulse.
She swallowed hard and stole her hand back, returned to face the sink instead of him, crossing her arms tightly over her chest and chewing intently on her lower lip.
"He was around when no one else was," she whispered, surprising him because he truly had not expected her to open up this time. "He listened and understood, unlike anyone else at the time, but I wouldn't call what I felt for him love. Not anymore," she mumbled, her eyes falling back into the empty sink, as if it held all those memories from her past.
"I'm sorry, Kate," he murmured, placing a gentle hand between her shoulder blades, fanning his fingers out to smooth along her neck, and she glanced to him tiredly.
"Aside from needing to know every tidbit from my past, why do you care? Why can't you just let me be?"
He scoffed, because really?
"You know why," he said pointedly, sweeping his thumb back and forth over the top of her spine. "I just want you to be okay," he added honestly.
Her eyes shimmered, filling with the unwanted tears once more and he felt the panic swarm him, swelling in his chest. He was doing the opposite of his original intention; he was making it worse.
"Kate, I'm sorry - I didn't mean to - I just wanted to help, I swear, I-"
"Castle," she sighed, surprising and silencing him when she decided to lean into the length of his outstretched arm.
He cautiously reeled her body into his, allowed her to hide her face in his chest for as long as she needed, feeling her breathing even out as a few stray tears slipped into the fabric of his shirt. He didn't like hearing about the ways she had loved another man and the ways that man had broken her heart, but he cared about her, and if this was what she needed to feel the least bit closer to okay, he would be a source of support for her. He could do this much without screwing up.
"Thank you," she whispered into the juncture between his neck and his shoulder.
He squeezed at her nape where one of his hands was curled, anchoring her. "For-"
"For being there for me," she answered before he could ask, digging her fingers into his back before carefully lifting her head. "Even after everything."
He swiped a kiss across her forehead and allowed her to take the step back from his arms.
"Always."
Michael Royce ended up in prison the next day. But then Josh Davidson showed up.
And he was not some past love Castle had little reason to worry about. No, the built man with the killer smile was definitely a threat.
The jealously he felt was not subtle this time, didn't creep in skeptically as it had with her training officer. This time it raged like an angry thing inside his chest, bashing against the cage of his ribs, demanding freedom, and as Kate strolled towards the elevators with a motorcycle helmet tucked under her arm and the other around the tall, handsome man's waist, he let it free.
"Kate." The unintentionally harsh bark of her name had her startling to a halt just in front of the elevator doors. She murmured something to Josh and he went on ahead of her while she turned on her heel.
"It's none of your business, Castle," she sighed, as if she already knew what was coming, but he couldn't even be bothered by her dismissal. He had told himself that if she found happiness with someone else, he would bow out of her life as gracefully as he could, without causing a ruckus or a scene, but that plan was nonexistent now.
He couldn't let her go, not when he could still feel what they had once had still alive and palpable between them. Not when they still had a chance.
"You have a boyfriend?" he blurted, his mind fuming and frazzled and unable to come up with a more subtle way of phrasing his question.
Her jaw tensed and she took an intimidating step towards him, knowing the boys and Montgomery were unashamedly watching the exchange from across the bullpen.
"I'm going on a date, Rick. I'm single, I'm allowed to do that."
"How long have you been seeing this guy? Have you even-"
"That is none of your concern," she snapped quietly, the warning in her eyes daring him to question her. "And I don't owe you any explanation."
She escaped into the elevators before he could say another word, left him gaping after her, and Castle watched helplessly as the doors slid closed on her tightly crossed arms and disgruntled expression. She was going on a date with someone else.
Castle moped the entire night, thoughts of Kate and Josh and how their date might end torturing his mind for hours. Even with Alexis appeasing his behavior, sharing ice cream and watching movies with him on the couch until her self-imposed bedtime arrived, he still crawled into his own bed with a pulsing headache and a knot in his stomach.
He had recovered somewhat by the next morning, throwing himself into his writing, burying himself in the shaky world of Nikki Heat and Jameson Rook. For months, it had been difficult to write about characters that had ultimately been inspired by the two of them, seeing her face every time he pictured Nikki and having to slam his laptop closed, but since he had continued shadowing her again, inspiration had come creeping back in.
He was currently working on a scene where Nikki encounters a boyfriend from the past and Rook deals with a good dose of jealousy. Relating to Rook's chagrin all too well, it felt almost therapeutic to write the out the situation, but maybe that was only because in his fictional world, he already knew who Nikki would choose.
Despite his chapter's worth of achievements and slight improvement in mood, Castle still wasn't prepared to see Kate on the other side of his door later that evening. Apparently, the feeling was mutual, because when she saw it was he who answered her knocking, she lowered her gaze to the ground.
"I'm just here to pick up Alexis, for dinner," she explained without looking at him and he sighed, leaning against the door. He couldn't help softening at the sight of her and how she was here for his daughter, pushing his pride to the side and admitting to himself that maybe his behavior the day before had been somewhat out of line, especially for her workplace.
"I'm sorry," he murmured. "For how I acted yesterday."
Kate apprehensively met his gaze, but the tense line of her body seemed to loosen and he could slowly feel her guard lowering for him.
"You ruined it," she chuckled, but it was a hollow sound, and he didn't understand.
"Ruined it?"
"My date. Josh and I, we met a few weeks ago, but with our busy schedules, last night was the first chance we had to go on a real date." She was fidgeting, her fingers twisting and twining around each other, so visibly uncomfortable in telling him this. "But I think he always sort of knew that there had been someone, before him. I'm not exactly sure how, but when he saw you he just..." Her brow knitted thoughtfully and she shook her head. "He knew."
He couldn't say he was sorry, not sincerely. He hadn't known Josh, didn't know what kind of man he was, if he was even close to what Kate Beckett deserved, but if he was going off of that criteria, he may not fit the standards for her either.
"I wish I was sorry," he said and she huffed, a hint of a smile lacing along the curve of her lips.
"I knew you wouldn't be, Castle. Too busy huffing and puffing all over the place," she muttered, but she propped her shoulder against the doorframe just a few inches from him.
He grinned, feeling the weight that always settled over his chest when they had a fight lightening. "Can't help it, Beckett. Kind of ruins my plans of getting you back when you're waltzing out of the precinct with other guys."
Her eyes slid closed, the levity of their moment singlehandedly destroyed. But he refused to speak in subtext this time around, it got them nowhere and he didn't want to fall into another holding pattern with her.
"We talked about this," she reminded him quietly, but failed to move away when his fingers trailed over her waist.
"Well, if I remember correctly, you did most of the talking and I just sort of nodded along to-"
"Castle." He had moved closer as he spoke and she pressed a hand to his chest to keep what little distance she could between them. "I think you should go and let Alexis know I'm here."
He nodded, but somehow ended up with his forehead against hers instead.
"Just - give me a second," he murmured, savoring the familiar scent of her, the exotic mixture of cherries and musk and something that was so distinctly Kate.
She didn't know what to do with her hands, her palms flailing midair for a moment before migrating north to curl at his shoulders. His splayed at her ribs, feeling the bones expand under his touch, her breath rattling up her throat and past her lips as her lashes fluttered against his cheek.
"God, I miss you," he sighed, brushing his nose against hers, but swallowing hard, reining his control back in because he had no right to do this to her.
He was prepared to pull back, finally give Kate her space and stop crowding her against the door like some domineering bully, but her fingers clutched at his neck before he could, drew him back down and fit his mouth to hers.
Her lips parted for him the moment his tongue swept across her mouth, like no time had passed at all, and she rose up on her toes – no longer having her height as an advantage in the ballet flats she wore – kissing him deeper. His arms twined around her possessively, wanting her close, close as he could possibly get, and hauling her up against him before pressing her back into the doorframe so he could ease his knee between hers. Her fingers tightened in his shirt at the sudden friction and he caught the moan that crawled out of her throat with his teeth.
"Hey Dad is - oh! I'm sorry, I didn't mean to - I'll just-"
The retreating flash of red hair was the first thing he saw when both his and Kate's heads snapped in the direction of his teenage daughter's voice, and Kate quickly shoved at his hands, untangling them from around her waist and under her shirt.
"I'm sorry, I'm really sorry, I-"
"No, no, Alexis, it's fine," Kate assured her, hastily smoothing her hair and straightening her shirt, still a little flushed and out of breath, but much calmer than he had expected.
Far more put together than he was - still standing dazedly in the open doorway, watching the exchange between Kate and his daughter dumbly.
"Are you ready to go?" Kate asked her lightly. "If you still want to go…"
Alexis nodded quickly, fiddling with the necklace around her throat, waiting for something.
Kate shot him a pointed look. "Castle, can you move? So Alexis can get her coat?"
"Oh." He took a jerky step sideways before getting his limbs under control and evenly making his way back into the loft.
Alexis smirked as she reached inside the closet by the front door and retrieved her pea coat, fixing her braid over the collar and sending Kate an expectant glance over her shoulder.
"I'll have her back in a couple of hours," she said shortly, not looking at him, but he merely nodded and didn't raise his eyes again until Kate was turned away from him and walking out the door.
"So," Alexis hummed from beside her and Kate rolled her eyes, keeping her gaze on the road as they drove through SoHo, towards the Italian restaurant across town that Alexis favored. Despite her breakup with Castle, Beckett had managed to keep a close relationship with his daughter, but Alexis had never stopped advocating for a reconciliation between the two of them. And after walking in on them making out against the front door, she had quite a bit of ammunition.
"We're not going to talk about it."
"Kate," she whined, Little Castle suddenly sounding so much like Big Castle.
"No."
"But-"
"Alexis, we're going to dinner to talk about you and your love life, not… me."
"In that case, I have a question."
"Shoot," she said more confidently than she felt.
"How do you know when you're in love? Real love, like with… well, you know."
Kate wanted to drop her head to the steering wheel in exasperation. Alexis usually never mentioned her father or their past relationship on these girls' nights they had every few weeks, knowing the subject was touchy. His daughter hadn't necessarily taken a side after the whole ordeal in the summer, opting instead to treat them both equally. It had surprised Beckett at first, considering how protective Alexis was of her family, but then Kate had realized, at some point, Alexis had made her family too.
"All the songs make sense," she sighed, repeating the same answer she had given to Castle when he had asked her the same question two nights ago.
"That's so true!" Alexis answered enthusiastically. "I was just telling my dad how everything makes sense now. All the songs and the poems and even the movies, it's just amazing."
Kate chuckled softly at the awe in the girl's voice as she continued rattling on, drifting away from Kate's relationship with her father and deeper into the budding romance happening between her and Ashley. Kate listened to her, nodded at all right times, knowing all too well what this was - the innocence and dreamy haze of being in love for the first time. She had felt that way once upon a time, but her world had quickly been drained of all types of starry-eyed innocence on a cold, January night. She saw people for what they were now, no longer trusting blindly nor fully like Alexis still tended to. It made her worry for the teen at times, wondering if she would have what it takes to make it when thrust into the real world and all of its harsh cruelties, but when she glanced over and caught the sparkle in his daughter's blue eyes, she fiercely hoped Alexis never lost her pure form of integrity.