A/N: Hey, guys! Yeah, I know. It's been almost 3 weeks, but they've been very eventful 3 weeks. You guys know how life can be a bitch sometimes, and adding that to my chronic lazyness is not helpful at all.

Anyway, this is the last chapter to this story. I will be hopefully posting a short epilogue soon. Won't give you a date cause I would surely miss it.

You guys have been great with your reviews and follows and all that. I am sorry I haven't been replying lately, but yeah, life again. I will try to get back to all of you as soon as I can. You rock and make all the writer's block and frustration worthwhile. Thank you.

ENJOY!

Chapter 4

When Castle arrived at the loft, he found his son and fiancée working in the kitchen in apparent harmony. Kate was rolling what appeared to be cookie dough on the counter and Aidan was holding a bell cookie cutter, looking as the detective worked, and eager to start with his assigned job of cutting the delicious forms.

He smiled as he approached them and left the paper bags on the counter next to the fridge.

"Hey." He greeted. "I see you worked out your differences." He muttered in Kate's ear, as he reached to ruffle the boy's hair. Then, he leaned into his girlfriend's space and stole a kiss from her lips, making her chuckle. "Hi gorgeous."

"Hi handsome." She laughed against his lips. "We worked it out." She offered. "And now we're going to celebrate by eating ourselves into a sugar coma. What do you say? Want to join us?"

"Sure!" He replied, his face brightening at the prospect of spending the evening decorating and eating Christmas cookies. "Just let me get changed and I'll be right back."

Once the writer disappeared into their bedroom, Kate turned her attention to Aidan, who was playing with some of the leftover batter as if it were some kind of sticky play dough.

"Hey, munchkin. You remember you can't tell daddy about the baby, right?" She reminded him. "We will tell him tomorrow night when I get back from work."

"It will be daddy's first Christmas present." The kid chimed in. "I know."

"Exactly." Kate smirked. "You will be my little elf." She added, winking conspiratorially at the boy. "You sure you'll be able to wait up for me? It might be way past your bedtime when I get home."

"I will wait. I have a plan." He whispered, asking her to come closer by wiggling his little finger. "I'm going to stay up to see Santa." He confessed. "My friend Jamie said he saw him leaving his presents last year and I want to see him too."

"Ooh." The detective nodded amused. "I see. Well, good luck, honey."

Kate smirked as she started transferring the already cut cookies onto a baking sheet, so she could put them in the oven when they took out their first batch. She placed the pan on the other end of the counter and turned to the boy again, her hands at her hips.

"Ok, scullion. Time to cut more cookies. Choose a shape."

Aidan checked all the different cookie cutters they had scattered on the kitchen island, tapping his index finger against his chin in thought, completely undecided.

"We already have gingerbread men and bells." Kate prompted. "Now what?"

"Um… Reindeers!" He exclaimed, picking said cutter from the counter. "We can paint their noses red, so they look like Rudolf."

"Did I hear Rudolf cookies?" Castle asked, walking out of his office, zipping up his worn out, blue hoodie. "Those are my favorite!"

"We're giving them red noses and all, daddy. Wanna help?"

"Of course, buddy. What do I do?" He asked, stepping next to his son and looking at Kate.

The detective helped Aidan finish cutting the shapes and handed Castle a pair of oven mittens. "For now, you can take out our first batch" She ordered, winking at him and patting his ass when he walked by her. "Then you can help me roll out more dough."

An hour and a half later, the three of them were sitting at the dinner table, each with a tube of glaze in hand, decorating dozens of delicious cookies.

Aidan was completely entranced by the activity,

"Wow, look at that Rudolf!" Castle praised, his boy. "You're a little artist, but you need to put the frosting on the cookies, son, not on you." He reached for the boy's head and brushed some yellow glaze away, picking up some of it and putting it in his mouth. "Yummy."

Aidan smiled broadly at him and pointed at his father's cookie bells. "That one looks funny, daddy." The boy said, his face breaking into a grin.

Kate laughed and picked up the aforementioned cookie, to take a closer look at it. "Yeah, Castle. We're making jingle bells, not high as heck bells." She joked.

Aidan looked at her a little confused about her comment, but smiled, turning to his dad with a solemn look. "Daddy, bells don't have eyes."

"They don't?!" The writer exclaimed in mock surprise. "You can't be serious."

"They don't!" The boy insisted. "But I like yours. They're cool."

Castle's face softened at his son's words, turning into a smug grin mere seconds later when he turned to look at his fiancée. "Ha! See? My bells are cool. Aidan said so."

"Mhm." She just replied, pasting a candy button on her last gingerbread man. "What about my little men, huh? Aren't they cool too?"

Aidan stretched his neck to look at Kate's cookies that were lining up, painting a colorful parade on the table. "Yeah. You made Santa!" The boy said; picking the cookie up and biting its head off.

Both adults laughed at the kid's antics, looking at each other with a stupid and proud grin on their faces before going back to their task.

Kate sighed, picking up a plain gingerbread man and a tube of red frosting. "I guess I'll have to make a new Santa."

They put the boy to bed at 9 pm. He had fallen asleep snuggled between the two of them, his head on Kate's chest, while they watched his favorite movie in the world. Cars 2. He was obsessed with it and it was always his choice for movie night. They had watched it so many times that every single member of the family, including Lanie and the boys, could quote the whole thing from start to end.

After cleaning up the kitchen and putting away all the cookies into containers and little plastic baggies to give away to friends and family, they retired to their bedroom for the night.

It was then, when they were both sitting in bed side by side and alone, that Castle asked the feared question.

"So, what was the problem? Did he tell you why he was so mad?"

Kate took a big gulp of air and bit her lip, trying to come up with a good answer so he would stop digging for more. "Um… yeah, but it was all a misunderstanding." She explained vaguely, turning the page of the book she was pretending to read.

Castle frowned. "A misunderstanding about what?" He asked again.

She sighed. She should know by now that her fiancé was too curious to stop at the first question. "Just something I told Lanie on the phone."

"Yeah, but about what? What were you talking to her about?" He inquired, his curiosity growing even more at her reluctance to talk about it.

Kate rolled her eyes and closed her book. "It was nothing, Castle."

"Then why don't you want to tell me about it, Kate?" He was amused by it all, she could tell from the tone of his voice. "Come on. I suffered through it too. I deserve to know."

"Okay. I was talking to her about your Christmas present." She blurted, her gaze focused on the duvet. "That's why I didn't want to tell you."

Castle's brow furrowed once again, looking at her with confused blue eyes. "My Christmas present? That's what caused this ordeal? Why?"

Kate shrugged. "He misunderstood my words. That's it."

"I still don't get it. Why would Aidan get mad at you about a gift? It doesn't make any sense."

"Castle, he's a four year old who misunderstood an adult conversation. It's not so hard to understand." She muttered annoyed. If he kept asking, she was going to blurt it out in frustration and she wanted to wait. She wanted to do it right.

"Ok. Fine. Don't tell me." Castle whined.

He was a little irritated by her secrecy, she could tell, but there was nothing she could do about it. "You will find out soon enough, babe. I just don't want to give away anything about your gift. It's a surprise."

"A good surprise?" He winced.

"Rick, it's a gift. How bad do you think it can be?"

She was nervous. She was so very nervous. She had been fidgety all day, and jumpy too, but this was a very important day for her. For them.

The time had been passing by incredibly slow and work had been unusually boring for Christmas season. The holidays were normally on of the busiest times of the year for them. It seemed that the ever-present joy and happiness made people snap in the worst of ways, but apparently, this year was an exception.

She checked her watch for the thousandth time. It was almost 10 pm. Two more hours and she'd be able to go home to her family and give Castle his little present.

She sighed. She knew he loved kids. Just the way he had reacted when he found out about Aidan was proof of it. He had been thrilled to become a dad again and that had served to reaffirm how much he loved that role.

The truth was, that they had never discussed children beyond the idea of her adopting Aidan. They had never talked about it. Kids had been mentioned once or twice in casual conversations, but it had never gone any farther.

Yet, here she was, four plastic sticks and a blood test later, trying to make her heart go back to a normal rate after thinking about how her fiancé would take the big news.

Maybe her fear was a little bit unfounded, but this was totally new for her. It was true that she had been a mother to Aidan for the last year and a half, and it was true that she loved every little part of it, but even though she was already a mom in practice, the truth was that pregnancy, labor and newborn babies were a completely new world for her.

She was terrified; and as much as she tried to tamper down her apprehension, the feeling was stronger than her will power.

Midnight arrived faster than she anticipated, given the speed time had been passing by all evening.

When the clock struck twelve, she picked up her bag, put on her coat and wished her colleagues a merry Christmas before heading out for the night.

She had a stop to make before she went home. Having come up with a way to tell Castle about the baby, she needed to buy one last little thing to finish putting her plan together. She really hoped it would work the way she wanted it to.

When she walked into the loft, she couldn't help but smile at the sight that welcomed her home. She felt like the luckiest woman on Earth.

Martha, Alexis and Castle, were all cuddled up on the couch with a sound asleep Aidan resting in their laps. 'It's a Wonderful Life' was on the TV, but all of them looked like they belonged in bed, their faces showing the tiredness and fatigue of the day at such a late hour. Yet, they made such a beautiful picture that she felt her eyes watering. Stupid hormones.

Kate walked into the living room area and leaned in to kiss her fiancé on the lips, brushing the sharp angle of his jaw with her thumb. "Hey." she whispered against his skin. "Merry Christmas."

Castle replied in kind, kissing her soundly, before letting go of her so she could say hi to the rest of the family.

Martha and Alexis welcomed her with open arms, both hugging her hard and asking about her day at work. The older woman patted the spot beside her on the couch, silently asking her to sit with them, and she did.

"How was your night, guys?"

"It was good." Alexis replied, her eyes soft and tired. "We missed you, though. The bug's been asking about you every five minutes." She laughed.

Kate smiled and stroked the socked, little foot resting on Martha's lap. "Poor thing. I asked him to wait up for me…" She offered guiltily. "He should have gone to bed hours ago."

"He's fine, Kate." Castle assured her with a tender smile. "It's just one night. We can put him to bed now."

The writer didn't even move an inch when the boy stirred and rubbed his face against his thigh. "Not sleepy." He mumbled, his voice muffled by his father's leg. "I wait for Katie."

The boy's eyes were still closed when he turned his face around, rubbing a hand against one of them.

Kate left her spot on the couch and crouched before Castle to softly caress the kid's face. "Hi, baby. I'm home."

His bright blue eyes opened to her and he grinned. "Katie! Marry Christmas!" He yelled, launching himself into her arms and dropping sloppy kisses on her cheek. "I wait up for you! Can we give daddy his gift now?"

She chuckled when she noticed Castle's surprised expression at his son's words. He sure was intrigued. She could tell. Good. He was going to have the surprise of his life.

"Of course, honey. Why don't you go pick yours from the pile? Just one, ok?" She reminded him.

The previous year had been hard to keep him from opening every single package under the tree. Hopefully, this time it would be different, but just in case, Alexis followed the boy to the tree to keep an eye on him.

"Why do we have gifts if Santa hasn't come yet?" The boy asked as he picked one big package with Martha's name on it. "Who brought us these?"

"We did." Alexis explained. "These are our gifts to each other. We'll get Santa's after we go to bed tonight, so you better be good." The young woman admonished with a smirk.

"We leave the heavy lifting to old Saint Nick." Martha chirped, sipping from her glass of red and winking at her son.

"HA! Yeah…" Castle scoffed, earning an elbow to the ribs from Kate.

"Will you shush!"

"Sorry."

The young redhead laughed at her father and then removed their grandma's gift from the boy's hands before offering him one of the smaller boxes with the tag 'Little A' on it. "Uh, uh. This one's not yours, munchkin."

"But I want the big one!" He whined and reached for the gift, jumping when his sister lifted it over his head. "Gimme."

"That is grams', baby." Kate pointed. "I am sure Santa will bring you big presents tonight."

"But I want them now!"

"Aidan." Castle quarreled. "You heard your sister. If you don't behave Santa's gonna put you on the naughty list."

The boy's eyes went wide and stopped his hopping, raising his hands in surrender. "I am good, daddy. Sorry."

"S'ok, baby. Go open that one." Kate instructed, nodding at the box Alexis was holding now.

The kid did as told and picked up the gift from his sister's hands, tearing off the colorful paper and then stopping short when he saw the picture on the box.

"A phone?" He asked, his brows furrowed and his lower lip pouting out.

Castle laughed as he took out an identical device from a drawer. "Nope." He said, turning the thing on and wincing at the static noise that came out of it. "They're walkie-talkies!"

Aidan smiled, still a little confused and handed his walkie-talkie to his dad so he could turn it on for him. "Cool!"

"Now we can talk when you're upstairs playing in your room." Castle exclaimed, handing the receiver to his son.

The boy's face fell as soon as his father pronounced those words. "I don't like playing in my room. It's scary!" He yelled, dropping the device and latching onto Kate's leg, like he always did when he was upset.

"Bug." The detective called, tapping on his crown. "Come on, baby. Daddy just meant that now you'll be able to talk when you guys are in different rooms. Right?" She prompted, glaring at her fiancé.

"Um, yeah. Of course, buddy." He rushed to reassure the boy. "You don't have to play in your room if you don't want to."

Aidan unstuck his face from Kate's leg and looked up at him. "Really?" He pouted.

"Really."

"Okay."

The boy let go of Kate's leg and grabbed the walkie-talkie from where it had landed on the floor, giving everyone in the room a sly smile.

They really needed to figure out how to deal with his fear of being alone.

Brushing a rebel strand of hair out of the kid's face, Kate cleared her throat and asked, "Ok, who's next?"

"ME!" Castle screeched, reaching out to grab a pretty small box with his name on it.

Kate put a hand to his chest and narrowed her eyes at him, shaking her head and retrieving the box from his hands. "Oh, no. You're going last, mister."

"What? Why?" The writer whined.

Kate smirked mischievously, patting his chest. "Because…" She started, winking at Aidan. "Yours is the most important one."

Martha and Alexis, who had helped her choose the new watch she was supposed to give him, looked at each other more than a little confused making her chuckle.

Oh, yeah. They didn't know either.

Everyone but Castle had already opened their gifts, and even though she knew how much he loved seeing his family happy and enjoying their Christmas presents, she knew her fiancé was starting to get anxious. He loved surprises more than anybody and she had made him wait long enough.

"Ok, Castle. Your turn." She announced, getting everybody's attention.

The writer reached for the last little box that was left under the tree, but Kate stopped him mid action. "Uh, uh. We'll save that one for later." She ordered, producing a package from behind her. "Open this one first."

She handed the packet to him, but pulled it away right when he was going to grab it. "You will have to share it, though." She added, realizing that the surprise was going to affect every single one of them.

"Oooh." Castle exclaimed. "You got us new laser tag gear?" He asked, eager to get his gift.

Kate chuckled and shook her head. "Uh, nope." She replied. But I got you a new future player. She thought to herself, finally handing him the present with a broad smile on her face.

"It must be something really big." Rick laughed. "I know that smile."

She just nodded, nervously biting her lower lip. "Oh, babe. You have no idea."

Once he had the package in his hands he started fondling it and turning it around, trying to figure out what it was, knowing how much it bothered her when he stalled like that.

"Ugh. Castle!" Kate whined. "It'd be nice if you opened it this Christmas."

"Ok. Ok!"

He removed the wrapping paper and pulled out a red, white and green stocking, adorned with little snow flakes and candy canes. It matched the pattern of their family set, but this one had no name on it.

"A stocking?" He asked incredulous. "Um. Thanks. I… uh… I guess mine was getting old."

Kate snorted. "Well, it is not for you, babe. I told you, you would have to share." She reminded him, smiling at his slow nod. "Why don't you look inside?"

"Yeah. Inside, daddy." Aidan cheered.

"You know what this is?" He asked the kid, narrowing his eyes. "You two planned this together, didn't you?"

The boy nodded and gave him a sly grin. "Inside, daddy." He insisted.

"Okay. Inside."

He put his hand into the stocking and took out a folded piece of paper and a little plastic bag with a cookie inside.

"Alright, let's see." He mumbled, unfolding the piece of paper. "Um, this is a…" His eyes lifted from the paper and he swallowed. "A medical report."

Kate heard somebody gasp behind her and turned to find Alexis with a hand to her mouth and her eyes wide open. She nodded, knowing the girl had figured out what it was, and then felt her heart melt at the look of pure joy she got in reply.

"There's your name on it, Kate."

"Yeah. I know." She mocked. "Keep reading."

"Hemoglobin, hormones levels…" He scanned the document, trying to figure out what made it so important. "Oh, my God." He gasped at last. "Kate?"

The detective nodded, tears starting to gather in her eyes.

"It… It says 'pregnancy: positive' here."

"Uh huh."

"We're… We're pregnant? Oh, God. We're having a baby!" He screamed, passing the piece of paper to his mother, who was already brushing away a traitorous tear. "Oh, Kate." He sighed, pulling her into a tight hug.

"Daddy! You didn't see my gift!" Aidan complained. "I made it."

The writer pulled away from his fiancée and took a look at the little package that he was still holding in his hand. The cookie.

"You made this?" He asked impressed, gazing at the rounded form. It had a smiley face drawn with red frosting on one side and on the other it said 'Castle Baby #3' in quirky multicolor letters.

Castle laughed at the inscription and leaned down to pick his son up. "I love it, buddy. Thank you." He whispered against the boy's forehead. "I can't believe you wrote that!"

Aidan blushed. "Katie helped me." He offered. "But I chose the colors."

"Oh. Well done. I love the smiley face too."

The kid beamed at him and hugged him hard. "You know what's the best part?" He asked, his eyes wide. "I am going to be a big brother!"

After having received the customary congratulations from his mother and daughter, Castle hung the new stocking by the fireplace, right beside Aidan's, tugging at the soft fabric as he stepped away and towards his family.

"This is the best Christmas ever." He said, turning around and pulling Kate into his arms once again.

"Wait until next year." She whispered against his skin. "I think it will beat this one by a lot."

Castle could only nod, burying his head in Kate's shoulder. Next year was going to be extraordinary for sure.

THE END

Short epilogue coming soon.

Thank you so much for joining me on this journey. It has been great having you onboard. Leave a review if you feel like it. I would love to know what you think.

Big thank you to my own personal cheer leader, Tshlw. I know I wouldn't have finish this without you nagging me all the time haha. Also thank you for editing and proof reading every time I freaked out. Love you!