A/N: Hi, fellas! I am sorry this took so long. I am crazy busy at work and to be honest, writing is being a little too hard for me lately. I'm coming from a very long period without writing at all, so be patient, pretty please?

Also, I know this story is supposed to happen around Christmas time, so if it happens to end when it's almost Easter time IRL (hopefully not), or whatever, just deal with me. I am always late for eveything :P

I want to thank you all for being so supportive and for all the nice reviews you left for me and all the follows and favorites. It means the world to me and I am forever grateful.

Thanks to the amazing Tshlw for being the best in the whole world and editing this for me. Any mistake is all mine.

Here's the chapeter, now. ENJOY!

Chapter 2

Aidan had calmed down by the time they got to the loft, but he had been strangely quiet and somber all the way there.

He never let go of his dad's hand and kept pulling him away from Kate by forcing Castle to run and pick him up whenever the writer tried to wrap his free arm around his fiancée.

Kate didn't know what to do. She had literally no idea of what had happened to the boy that had made him so mad at her when she hadn't seen him since the morning and then he had been the sweet little boy he always was.

Once they arrived at the loft, and after putting away their coats, Kate headed to the master bedroom to get into comfy clothes. Castle stayed behind turning on the TV and setting Aidan on the couch watching his favorite cartoons until they got his bath ready. Then, he disappeared into the bedroom too.

When he entered the room he found Kate sitting on the bed, her head resting on her hands. He could tell that Aidan's strange behavior was really getting to her.

"Hey." He tried to gain her attention, but she didn't look up.

He sat down beside her and stroked the top of her head, then pulled her closer to him, circling his arm around her shoulders. "Come on, Kate. It's just a temper tantrum. It'll be ok."

She raised her head from her hands and he could tell that she was on the verge of tears. "Will it?" She whimpered. "He's never been like this with me before. I don't even know what I have done for him to be so disgruntled."

"Well… Adaptation is hard, Kate." Castle tried to reassure her.

"Adaptation? He's lived here with us for over a year. Isn't it a bit late for that?"

Castle shrugged and hugged her closer. "I have no idea. This is my first time going through this. I guess we're all rookies here." He smiled. "Alexis was with me since birth, so she didn't have much of a choice. By the time she was three I had already gained her little heart with the millions of toys I bought her and the unbreakable rule of having ice cream for dinner every night."

Kate laughed at that and reached for his free hand that was resting on her thigh. "I'm sure that helped, Castle, but I know that is not why Alexis adores you. You are a wonderful dad."

The writer smiled sweetly at her. "Thank you. So are you." At the funny look that remark gained him, he kept talking. "You are an amazing mother, Kate. Seriously. I would never have thought to find myself in this situation. Ever. But it happened and to be honest, the way you reacted to all of it really surprised me. You have no idea how thankful I am to have you by my side."

Kate's eyes became glassy again and he smiled and kissed the top of her head, pressing his cheek against it. "You've been amazing with Aidan from the beginning; even when we didn't know if he was mine for sure. He loves you, Kate, and whatever it is that is bothering him right now, it will pass. Everything will be fine again."

Kate gave him a tight smile that didn't make it to her eyes, but she wanted to reassure him, even if she was worried, not only about Aidan's huff, but also about how would the boy react when she dropped the bomb about her pregnancy.

With a last kiss to the top of her head, Castle stood up and offered her his hand to help her get up. "Come on, I have an idea."

She took his hand, but couldn't help narrowing her eyes at him, fearing what his little brain had come up with. "Do I want to know what it is?" She questioned.

"You do." Castle laughed. "So. How about I start dinner and you go give Aidan his bath?" That granted him a quirked eyebrow, but she didn't talk. "You know how much he loves bath time."

Kate smiled. "Castle. He loves bath time because it is 'daddy and Aidan' bonding time. He loves playing with you and listen to all the fun pirate stories you make up for him. I don't think me taking that away will solve anything."

"But we can make it be 'mommy and Aidan' bonding time. Just this once." He countered, tilting his head to the side and squeezing the hand he was still holding.

The cop silently lamented that the mommy part wasn't exactly accurate; that as much as she wanted to be Aidan's mother, that was not the case yet. But it would be. Some day.

"Come on. It'll be fun!" her fiancé insisted, pulling her forwards. "You'll see."

The bubbles were starting to form in the half empty tub and she checked the temperature of the water for the tenth time, making sure she was not going to scald the boy when she put him in there.

She wasn't used to doing this. Bath time was always Castle's duty. He was the one who was always home to do it and to the boy's delight, his daddy made bath time a real adventure.

She was normally the killjoy; scolding big Castle for making baby Castle too hyper right before his bed time, or giving them both a glare for splashing water on the floor.

Yeah. She was not the fun parent, but she could at least try.

"Okay." She mumbled to herself. "Let's do this."

She went down the stairs to the living area to get Aidan, who was still entranced in his cartoons, all huddled up on the couch.

"Hey, munchkin. Your bath is ready." She called a little bit uncertain of how this would go. "The sooner you get in, the more time you can play with your water toys."

Aidan turned to look at her, his face completely blank. He seemed to stop to think about it for a second, but he didn't move from the couch and, after a few seconds, he returned his full attention to the TV.

Both Castle and Beckett looked at each other in surprise. This for sure was not the usual behavior of their little boy. What the hell was going on with him?

"Aidan." Castle called from the kitchen, his stern tone making the child look in his direction immediately. "Go take you bath, buddy."

The use of the pet name didn't tarnish the intent of his father's order, so the boy hopped down off the couch and followed Kate upstairs, his hands in tight, little fists and tears threatening to fall out of his deep, blue eyes.

"I don't want a bath!" Aidan screamed for the third time. "I wanna watch cartoons!"

Kate sighed and ran a trembling hand through her hair. She had no idea what to do.

Normally, when the boy got into this level of distress, she was the one to make it better. She was the person Castle went to when Aidan was too stubborn, or was acting up. But this time… This time she was absolutely clueless because, whatever the problem was, she was part of it.

"Ok, Aidan, you need to take your clothes off and get in the tub. You already skipped bath time last night because you fell asleep on the couch." She pointed. "Come on, I'll help you."

The moment she reached for him, the boy stepped backwards, flinching when her hand brushed his wrist. "NO!"

"Aidan! Come on." She chided.

"NO! NO! NO!" The boy cried. "I DON'T WANNA!"

"I know you don't want to. But you have to." She sighed, feeling like she was running out of energy. "If you keep acting like a baby, you're going to bed without dinner."

Aidan frowned at her threat, but he just tightened his fists and screamed. "NO! DADDYYYYY! I want daddy!"

Kate froze. What was she doing so wrong? She just needed him to calm down and do what he was told. It was as simple as that. She had managed to 'tame' him a million times. Why wasn't it working now?

She reached for the boy, who had nowhere to go, since he was practically cornered against the wall after his previous retreat, and grabbed his shoulders, softly but firmly, then called his name until he looked back at her.

"Aidan, listen to me. I just need you to take off your clothes and get in the tub, ok? That's all you have to do. Please."

He did nothing. His gaze was lost somewhere above her shoulder and his lower lip was pouting out, making him look absolutely miserable.

And she had caused that.

How was she going to bring another child into the world, when she was incapable of dealing with the one they already had?

The tears that had been pooling in Aidan's eyes started to fall down his little face, making Kate's hear break. She couldn't see him like this. It made her want to pull him into her arms and never, ever let go of him.

And that's what she tried to do; but it was definitely a bad move.

The child jerked away from her when she tried to pull him closer, shoving her arms away from him and making her lose her balance, which resulted in her falling on her butt with a loud thump.

She couldn't keep the hurt away when she looked up at the boy. This was getting way out of hand. "Aidan!" She mumbled, almost inaudibly.

The boy just looked at her, his eyes wide as saucers, and then ran out of the bathroom crying for his father.

When Castle walked into the bathroom with Aidan perched on his hip, she was still trying to get up from the floor.

"What is going on here?" Rick asked, completely lost. "What are you doing there?"

"Taking a nap." She snapped, but then closed her eyes hard and, after a few seconds and a couple of deep breaths, she looked up at him apologetically, stretching her arm towards him. "Care to help me up?"

The writer put the boy down and reached for her immediately. "Oh. Sure." He grumbled. "What happened?"

"I… fell." She lied, rubbing her left elbow.

Castle narrowed his eyes and nodded. "Uh huh. And why was this little man screaming like he was being followed by an army of ghosts?" He inquired, turning his gaze towards Aidan, who was busy examining his naked feet. "Hmm?"

The boy shrugged, but didn't look up at his father.

"He doesn't want to take a bath." Kate supplied. "He doesn't let me even touch him, Castle." She almost sobbed. "I don't know what to do."

Rick sighed loudly and crouched in front of his son. "Ok, buddy. What's going on? You know you have to take your bath."

He only got a deeper frown from the child. "I know it's normally me who plays with you during bath time, but I am busy making dinner. Can't you be nice to Kate and help her a little bit? You guys can have fun together too."

"NO! She can go make dinner."

Castle huffed out his frustration and moved closer to the boy. "What's wrong with Kate, Aidan?" The writer questioned. "What's happened to make you so mad at her?"

Nothing. He didn't get any kind of response from the kid. Just his eyes locked to the ground and the pout of his lips.

"Baby, did I do anything that bothered you? You know you can tell me." Kate intervened, trying futilely to make the boy react.

"Aidan. You need to tell us what's wrong, buddy. You can't keep being mean to Kate. Kids are supposed to be nice to their mommies." Castle reprimanded.

At that, Aidan raised his gaze from the floor and looked at his father with a broken expression, letting the tears fall down his face again. "SHE'S NOT MY MOMMY!" He yelled, and then stormed to his room, closing the door behind him.

Castle stood in the middle of the hallway, looking between Aidan's bedroom door and the stairs Kate had sneaked away through when he tried to follow his son.

He had no idea what to do. He more than anything wanted to help, but the way to do it, totally escaped his mind.

It pained him to no end that two of the most important people in his life were unhappy and obviously suffering. He was at a loss about what was going on with Aidan, and until the boy didn't open up and talked about it, there was not much to do, so he decided to go comfort Kate and let Aidan simmer down before trying to talk to him again.

With a deep sigh, he walked down the stairs and to his bedroom, where he found Kate with her face sunken in her pillow.

"Hey." He practically whispered, not wanting to startle her. "Kate, it's going to be ok."

The detective sniffled and buried her face even deeper in the pillow. "You don't know that." Her muffled voice came out. "You heard him." She added, turning to face him at last. "I am not his mommy."

"That never mattered before. And it won't matter again after he comes out of his funk." Castle reassured her, sitting on the bed by her side. "You guys love each other madly. And moms and kids fight all the time. It's natural."

Kate rolled her eyes at that and grabbed a tissue from the box on her nightstand. "I thought that started once they were teenagers. He's four, Castle! He should be wanting snuggles and bed time stories, not worrying about who is or is not his mother."

"You are right, but what do you suggest we do? As you just said, he's only four. It's very hard to explain the situation to a kid that young."

The detective bit her lower lip and grabbed her fiancé's hand, squeezing lightly. "I can't wait anymore, Rick. We have to do it. The sooner the better."

Castle's eyes opened wide, his eyebrows shooting upwards, causing his forehead to crease. "You mean…"

"Yes." Kate proclaimed. "I don't want to wait until after the wedding."

"Ok." The writer nodded. "If that's what you want. I will call my lawyer first thing in the morning."

TBC.

Dun dun duuuun... Not a really huge cliffhanger, but well. It works haha

I hope you enjoyed the chapter. If you did, please let me know. If you didn't, please tell me why and what can I improve about it.

Thanks for reading and have a wonderful day/night.