A lot of fluff and cute theorising mixed in this chapter because post-XX I think that's what we all need!

Kate Beckett held her head in her hands as the car bumped along through the busy streets of central Boston. She'd pulled rank with Castle and was sat shotgun as he pouted like a child in the back seat behind Sorenson. The FBI agent was apparently oblivious to her discomfort, for which she was glad, as he concentrated on the road.

"I hate helicopters." She murmured to herself, her teeth gritted in response to her pounding temples. Beckett had always been a victim of altitude headaches, but the quick descent of the helicopter had messed with her head something fierce. The thundering in her ears was nauseating and the movement of the car was not helping her stomach to settle, she could feel bile rising in the back of her throat.

"How far out are we?" Castle piped up from the back, his eyes shifting from his paling wife to the busy road ahead uneasily.

"5 minutes, maybe less." Sorenson threw back, eyes still trained ahead.

"Kate?" Castle asked.

She looked around slowly, lifting her head out of her hands, to see him holding out a plastic water bottle.

'small sips' It was advice he'd given her many times, nursing her back to health; through stomach upsets, pregnancy, bad Chinese food, and now, motion sickness. It had always helped.

'Take small sips, it'll calm your stomach.' He said, handing her the plastic bottle before lifting her legs and sitting down beside her on the couch. Placing her legs back down over his he pulled a soft, cream blanket over the both of them.

"For now." Kate responded, less than impressed. When she'd agreed to this somehow she'd overlooked this part.

"It'll be worth it in the end." Castle replied with what was probably meant to be a charming smile, but in her hazy nausea-ridden state it seemed smug.

"Says the guy without a little alien sitting on their bladder." She huffed, taking a sip of the water before placing it down on the coffee table.

There was beat of silence.

"That'd be cool." Rick grinned to himself, his gaze directed away from her, distant.

"What?"

He turned to look at her, still grinning, excitement prevalent in his eyes, "If the baby was actually a little alien."

Kate groaned, but there was a small smile on her lips as she pulled the pillow out from behind her head and threw it into his face.

One throwaway comment from her had created the basis of her son's childhood. From then until Felix's birth Castle had refused to stop calling the baby 'little alien'. She'd get up in morning and he'd ask 'how's our little alien this morning?' When Felix had started to kick the jokes had been endless. The first time Rick had seen his son's foot pressing up against his wife's stomach he'd gasped and said, 'I'll call Ellen Ripley!' That comment had earned him a kick of his very own.

Over time the jokes had morphed into something more; alien plushies, constellation-covered bedsheets, brightly painted cardboard spaceships, and whispered bedtime stories about a little alien called Felix. She'd sit outside her son's bedroom door and listen carefully to tales of distant solar systems and space cowboys, not wanting to intrude or distract. Lullabies had always been her thing, but bedtime stories, they were Rick's domain, and The Little Alien was Felix's favourite. For Kate the nickname had morphed from a laughable annoyance into something truly endearing and meaningful.

It was strange that such a commonplace thing as a water bottle could remind a person so vividly of why they loved someone.

Stories. That was why she loved Richard Castle. His books. His story. Her story. The stories they unravelled to catch killers. They all merged together to create 'their story'. She doubted any couple in the world could hold a candle to it.

"Thank you, Rick." The softness in her tone was noted by both the men as she accepted the bottle of water.

"Here we are." Will pulled the car into a parking lot, talking as he navigated the vehicle neatly into a slot against the wall of the hotel, "I have an address for the grandmother. Charlestown. We should dump our bags and head over before it gets too late."

"Agreed." Kate was itching to get out of the car and go lie down, let Castle fuss over her until she fell asleep, but she had a job to do. There was a parentless and scared little boy out there and the more time they spent on this case the higher the chances grew that there wouldn't be a happy ending. She would never let that happen again; and as much as she begrudged Sorenson's presence on this case she knew that he wouldn't either.

But Castle… he knew. He'd held back her hair in the early days when she'd spent more time observing the toilet basin than at her husband, brought her coffee on the sleepless nights as the lights on the baby monitor had flashed at them, and held her hand tight on that first day of school as soon as she'd finished straightening that tiny, perfectly ironed tie. He'd been there. As much as Sorenson was dedicated, he wasn't a father. He hadn't told her explicitly, but she was a detective. When he opened his wallet there was a wedding photo, he'd made no personal phone calls since he'd arrived, and every dad Beckett knew jumped at the chance to mention their kid. He would have said something when she'd brought Felix up. Sorenson's ring finger was adorned with a modest gold band, but he didn't have any of the little quirks that came with having children. Those unconscious little looks in the rear-view mirror just to check on that sleeping face even when it wasn't there to see. The way your hands pat your pockets before you leave somewhere no matter your location just to make sure little hands haven't got to your keys. The distracted looks when you're away from home, worrying about the little things, like whether you remembered to put the drier on and left them with enough clean underwear, and the big things, like if they're going to be able to sleep without their favourite bedtime story.

And for all Castle's male pride and protective tendencies there was no way he would let it get in the way of saving little Barney Ryder.

"Kate, you coming?" Castle said as he knocked softly on the window of the front seat.

Beckett startled a little in response, "Uh… yeah."

He held her gaze, his brow creased in a worried fashion, securing the car door with a hand on the frame as she stepped out.

Will was already at the trunk, tugging out their overnight bags, half handing, half tossing them to a surprised Castle. Rick fumbled with the first bag in his desperation to catch it. The duffle almost seemed to tip out of his flailing arms in slow motion as it landed in the wet, potholed asphalt with a splash.

Rick swore. He looked up knowing exactly what famed look he was presently receiving from his wife. The intense hazel eyes paired with pursed lips created the most unimpressed stare, sure to instil shame in even the most unabashed of men.

He grabbed the bag, her bag, from the puddle and held it especially tight this time round.

"You can… borrow my pjs." He managed to mutter out, adverting his eyes to where a mildly amused FBI agent was holding Castle's own, perfectly dry, duffle. "That mine?" Castle commented quietly to himself, carefully taking it from Sorenson. Rick kept his head down as he moved toward the Hotel entrance and away from Beckett's hard stare.

She sighed, shaking her head lightly. After a moment she slammed the car door and followed the two men into the building.

It wasn't fancy. It was definitely not the worst place she'd ever spent the night by a long shot, but it didn't make the top ten either.

"I could have put us up at the Lenox you know, Sorenson." Castle stuck his hands in his pockets as he scanned the ceiling, noting the cracked, greyish appearance of the white paint at the corners.

Sorenson's nostrils flared but he didn't even glance at the writer as he approached the reception desk, ringing the bell there a little more aggressively than was strictly necessary, "As generous as that offer is Castle I am not in the habit of taking charity. This is what the FBI is paying for, so this is where the FBI agent is going to stay."

"I'm not an FBI agent." Rick said, leaning back against the desk as they waited.

"I'm well aware." Will sent Castle a thin-lipped façade of a polite smile, "And so if you wish to stay elsewhere then you're very welcome, but the car is FBI property and it's not going anywhere so I hope you enjoy your walk."

"Can I help you?" An elderly man interjected just as Castle's mouth opened to send a sharp quip back Sorenson's way.

He was slightly bent with age, a rather large pitted nose in the middle of his round, pink face. Large frames around watery blue eyes. Well-presented enough wearing a pressed, checked shirt and a friendly smile on his thin lips

"Yes," Will began confidently, then his face fell, "Uh…" He didn't know what to ask for. The thought of ordering a room for his ex-girlfriend and her husband to share was so unbearably awkward his brain had forgotten how to create sentences.

Kate rolled her eyes and strode up to the desk, "Two doubles, please." She told the man, who simply nodded with a smile and pushed his spectacles further up his nose.

Sorenson stiffened.

"After all," Castle began smugly, as the man behind the desk busied himself fetching the keys, "We've all got to do our bit to save the FBI some cash."

Beckett turned to Rick sharply, rising up on her toes to put her lips next to his ear, garnering an audible gulp from his throat, "Seriously, another word and you'll be sleeping on the floor, got it?" She whispered pointedly.

"Got it." Castle gulped again, muttering something about 'hotel carpets' and 'chaffing' as he accepted their room keys and followed her up the stairs; leaving Sorenson grinding his teeth, cheque in hand.

….

"And you have no idea who might have wanted to harm your son? Why they might want your Grandson?" Beckett softly inquired, her gaze trained on the distraught woman settled in the armchair before her, tissue in hand.

"None." The bloodshot brown eyes of the elderly, but still beautiful, Mrs Dana Ryder still seemed wide with shock at the news of her son and daughter-in-law's death. "My husband wasn't… a very present father, Simon and I were very close. I just always assumed if he was in trouble he would have told me. As for Barney…" The woman's bottom lip trembled, "I don't understand how this could happen."

"When did you last see your son, Mrs Ryder?" Sorenson's pen was poised over his notebook.

"Last weekend. Every other Sunday he brings Barney over for Lunch." The woman recalled.

"Fiona wasn't with him?" Beckett asked.

"No, but that wasn't unusual."

"How did he seem?"

Mrs Ryder fiddled with the tissue between her fingers in an agitated fashion, "Fine, at first. Normal."

"At first?" Castle leant forward in his seat. With two words he was suddenly ten times more intrigued.

"Yes," Dana Ryder began, "They were meant to stay till four, but they left early, around 3:15. I remember because I went to go check on the cake."

"Did he say why he was leaving, Mrs Ryder?" Sorenson said, scribbling in shorthand.

"No, but he left right after he finished his phone call." The woman grew even more anxious at the memory, "I took Barney with me to check on the cake. I heard the phone ring, by the time Barney and I came back Simon was saying goodbye."

Beckett chewed her lip, "You didn't hear any of the conversation?"

"No," Mrs Ryder wrung her hands, voice shaking, "but whatever it was Simon was very upset about it. He tried to hide it but I could tell he was rattled. He kissed me goodbye, grabbed Barney, and they left." The woman's voice caught on that last word.

Beckett got up, pulling out her phone and rounding the corner into the hall, she pressed the number for the boys and waited.

"Ryan." The other detective promptly answered, the buzz of the 12th precinct familiar in the background.

"Hey, I need you to run down a cell number. Find out who called Simon Ryder's cell at 3:15 pm last Sunday."

"How was he saying goodbye?" Castle said, still settled on the couch opposite their first victim's mother.

"Sorry?" Mrs Ryder's brow furrowed, confusion mixed with pain.

"Castle…" Sorenson warned.

"The tone of it what was it like?" The writer persisted.

"Um…" Dana Ryder looked between Sorenson and Castle unsurely, "Soft."

"Soft?" Will repeated, bothered by her choice of word.

"Yes. It was level, kind, but he seemed off, like he was trying to hide that he was scared. It was soft."

Sorenson didn't know what to make of it.

"So, he had a personal relationship with whoever was on the other end of that phone call." Castle concluded.

"You got that from 'soft'." Sorenson hissed.

"Mrs Ryder was there any chance your son was having an affair?" Rick said.

Sorenson looked about ready to put Castle in a headlock.

"No! No," The older woman shook her head almost violently, "Simon loved Fiona. He wasn't the type to cheat."

Will grabbed Castle's arm before he could speak again, pulling him up out of his seat and away, "What are you doing?"

"Determining that it was the victim's wife who called him at 3:15. People have very distinct voices during phone conversations. You don't even realise you're doing it but everyone's voice raises in pitch and pace when they're speaking to someone they don't know very well. Also, a 'soft' goodbye?" Castle raised his eyebrows, "I think he loved whoever was on the end of the line and the only other two people he loved were in the next room."

"And you call this detective work?" Sorenson scoffed.

Beckett strode up to them, slipping her phone into her pocket as she approached, "Ryan already had the phone records. A call at 3:12 came in from a cell registered to Fiona Ryder."

Castle gave Sorenson a pointed look, a smirk growing at the corners of his mouth.

…

"How was dinner? Did you eat all your green beans?"

The 6 year old nodded solemnly, his hand propping up his head as he stared into the computer on his father's desk, regarding his mother with a slightly guarded gaze. He'd been let down by her twice over today. A shard of intense guilt was sitting in Beckett's heart as she watched her son's eyelids flutter with fatigue.

"Alexis said I wouldn't be strong enough to play lazer tag if I didn't eat them all." The boy supplied.

"She's right." Kate smiled. Alexis was Felix's idol, there was pretty much nothing she couldn't convince the boy to do.

Felix drew his knees up and tucked his chin into the dip between them, "Where's daddy?"

"He's in the bathroom. You want to say goodnight?" Kate asked, hearing the shower turn off, and the thump of a pair of large feet hitting the floor.

Felix nodded again, his eyelids drooping as he stifled a yawn.

"Castle, your son wants to say goodnight." Beckett called.

There was another thump and a click of the lock before the man emerged, dressed only in a pair of his expensive blue boxer shorts, having surrendered his pyjamas to his wife.

"Hey, Dynamo," Rick bent over Kate's shoulder.

Felix perked up a little, "Hey, daddy, when are you and mommy coming home?" The boy's bright, hopeful eyes twisted the shard in Kate's heart sharply.

"Soon," Rick enthused.

That obviously wasn't the answer Felix had been looking for because his gaze fell and his bottom lip jutted.

"How about…" Castle decided, "You get Gram to carry the laptop up to your room and I can tell you a bedtime story?"

A small smile grew on Felix's lips and he quickly hopped down off the desk chair. The patter of eager little feet could be heard as he sped off to fetch his grandmother.

Kate threaded her fingers through Castle's where they rested on the arm of the chair she was sat in, "You can have my seat."

"You can stay." Rick suggested as she lifted herself out of the chair.

"No, Castle," Kate looped her arms around her husband's neck, his hands appearing on her waist in response, "Anyway, I'm only going to be right over there. Just… wake me up if I fall asleep before he says goodnight, okay?" She knew it was unlikely, it was still early, but she wanted to be sure.

"Okay," Castle agreed softly.

Kate drew her fingernails over the nape of his neck with one hand, the other clutching his bare shoulder. She smiled in that sweet, suggestive way that meant she wanted something very particular from him.

Rick brought down his forehead to meet hers, noses brushing, letting Kate make the final move. The way they kissed was firm and confident, the way you kiss when you know every crease and plain of your partner's lips. There was no need for exploration, this land was already mapped, but it didn't mean they didn't still manage to surprise each other. Rick slipped a hand under the shirt she was wearing, his pyjama shirt, a warm palm pressing against her lower back. Her fingers tightened in his hair as she let forth a small, stifled moan.

"Before this goes any further I feel like I should make my presence known." A familiar female voice emanated from the laptop on the desk.

Kate broke the kiss and shoved her husband away with a short gasp, "Martha?"

"Don't worry Katherine, it's hardly the worst thing I've caught you two kids doing." The woman said, laughter in her tone as she climbed the stairs, laptop in arms.

Rick groaned, "Mother."

"Hey Dynamo, I think your dad's ready to tell you that story now." Martha ended the conversation there as she placed the laptop on a chair beside Felix's bed.

…

Silence fell as Castle switched off the laptop. He walked to the edge of the bed, low city lights and flashes from passing cars fluttered against the thin fabric of a curtain that was drawn in front of the window opposite the bed.

Kate's husband was a silhouette against it, but she kept her eyes down, a bedside lamp illuminating the pages she was holding; the case file she'd spent the last 30 minutes flicking through.

"So…" Rick lifted the covers and climbed in, the mattress shifting under his weight.

"So?" Kate wasn't going to play his game.

"It's only 8:30." Castle continued.

Kate hummed in response, an eyebrow arching. She kept her gaze on the file even though she could feel his own on her face.

Castle began to wonder if something else was the matter, "You still got that headache?"

"I'm fine now." She answered. It was the truth, the pain had subsided hours ago.

"Okay," Rick laid down, but turned toward her and propped his head up on his elbow, "Because it's not every night we're somewhere where we can be sure of no little disturbances."

Kate couldn't stop smiling as she chastised him, "Castle, my ex-boyfriend is in the next room."

He huffed, "It's not my fault if you're loud."

"Castle!" Kate utilised what she had at hand and rapped him in the face with the case file.

"Actually, no, I take that back, because it kind of is, isn't it?" Unfazed, he seemed overly smug at the idea of it.

"Jackass," Beckett muttered, placing the file on the nightstand, knowing she wouldn't be able to concentrate now.

Castle drew up, placing a hand between her knees to steady himself as he brushed his lips along her jaw.

"Castle," Her warning was a weak one.

Kate turned to face him and their lips met. Castle moved his arm to encircle her, pulling her down the pillows till she was lying underneath him.

"You're… incorrigible." Beckett murmured against his mouth.

"Come on, Beckett," Castle lips left her mouth to travel down her neck, his tongue flicking out to sweep light along her collarbone, "Isn't it about time we tried to make another little Castle baby."

Beckett grabbed his chin and forced him to look up at her, "I thought we were already trying?"

Kate wasn't quite sure how they'd got there, but about a month they'd discussed it. She was pretty sure it'd been playing on his mind for a while now; 7 years could be considered quite the age gap between two siblings, but until recently they'd been perfectly happy having just the one. However, Castle wasn't getting any younger and neither was she and so, though in this day and age older parents were more common, time had forced them to realise that maybe another one was something they wanted, and if they did want more it might have to be sooner rather than later.

'Castle, have you seen my pills?' She'd been searching through the medicine cabinet for the past few minutes.

'Which kind?' A sleepy voice echoed from the bedroom.

'The important kind.' She almost growled, continuing to search, knocking a couple of band-aid packets and a spare toothbrush out onto the floor. 'I can't find them anywhere.'

As she dug around the contents of the cabinet Rick approached, grabbing her hips from behind he pulled her into him, earning a short gasp in reponse.

'Well then… maybe you just don't take them?' The words were muffled against her neck.

Ok, so maybe there hadn't been much of a 'discussion'.

Castle's brow furrowed, he drew away and sat up, grabbing her hands to take her with him, "We haven't been 'trying' so much as 'not not trying'."

"Eloquent, coming from the best-selling author." Kate laughed, her hands resting absentmindedly on his chest.

"What I'm saying is… I think we should try harder." Rick grimaced at his own words, "I'm really not on form tonight."

"Babe, I want this too, but tonight's not the right time. Once this case is done and we save that little boy we can think about bringing another one into the world, okay?"

Castle visibly conceded, "Okay," He paused, "You think we have a good chance of saving Barney?"

Kate ran her hands up and down her husband's arms as she spoke in a comforting gesture, more for her sake than his, "I think so. I mean, if they wanted him dead they'd have killed him with his parents, and there's been no ransom demand yet."

"That we know of." Castle interjected.

"The FBI has got agents at Mrs Ryder's house if anyone phones her we'll know."

"While there's life there is hope." Rick quoted, as true in this context as it was in its original.

There was beat of silence.

"But does a ransom even make sense?" This case was agitating Castle more than most, though he'd been supressing it, the element of the lost 6 year old had taken all the excitement out of it and left only the uncertainty, "I mean why kill the parents if you want a ransom? Plus, there was tons of money in that car why didn't they search it? The Ryder's were running from something, maybe the killer needed them dead but didn't have the heart to kill the kid, but he was a witness so they decided kidnapping him was safer."

"That's actually…" Beckett quirked her head, "… a plausible-ish theory?"

Castle gasped, "Maybe the killer was a hired gun, an assassin paid to dispose of the Ryders after they betrayed the trust of a wealthy government official, but the assassin looks into the face of little Barney Ryder and suddenly feels filled with remorse. Torn, he takes the child from the wreckage to raise as his own, like Tom Stark and Davey Danner, using his contacts to create new false identities for himself and his young ward."

"And you've ruined it." Beckett sighed, falling back into the pillows. "Anyway, only the driver's window was damaged, it was hardy a 'wreckage'."

"Which I would have known if you'd let come to the crime scene instead of forcing me to go make small talk with Betty Crocker and co."

Kate ignored his complaint and carried on, "Simon Ryder was a high-profile prosecutor, so it's much more likely one of the criminals he put away got out, still blamed him for their time stuck behind bars, and came after him and his family."

"And chased them all the way to Brownsville?" Castle shook his head, then a spark flashed behind his eyes, "Wait! Why were they in Brownsville?"

Kate sat back up sharply, "That's not the most direct way to the border from Boston. How did we miss that?" She said, deep-seated disappointment in her tone.

"They were there for a reason, something they had to do before they left the country." Rick added.

"Or someone they had to meet?"

"And maybe that person's our killer."

Thank you for the amazing response to this story! Your support is the reason I keep on writing.