A/N: This is a fill for the prompt "Castle figures out Beckett's pregnancy before she does" on castlefanficprompts on tumblr. There was already a fill for this one, but the idea was too fun for me to pass up, so I decided to give it a shot. I've rated this M for future chapters. Hope you enjoy!

It was one of those cases that they hated; the one where nothing made sense and left them running in circles. Castle couldn't even come up with a creative idea about how the mob or the CIA or ninjas was involved. The two of them stared at the murder board as if waiting for the answer to jump out at them. Beckett was leaning against her desk, tapping her foot; Castle was in his seat, his head tilted like a puppy's.

"Maybe...nah," he said. Beckett sighed. They had been doing this for a good two hours, waiting to see if any of the thinly connected leads that Ryan and Espo were chasing down would turn up any dirt. Castle stood and grabbed his empty mug. "Refill?" he asked, nodding towards her cup.

Beckett looked down at hers, noticing for the first time that it was still full. And cold.

"Uh, sure," she said.

"It's full," he said. She raised her eyebrow. At this point, she didn't even really need to scold him about pointing out the obvious. "It's just...you always drink coffee."

"Yeah, I must've just forgotten about it."

"Okay...I'll go make you another?"

"That'd be great, thanks."

Castle took the time to draw the little heart in her latte, just the way she liked it. When he got back to her desk she smiled gratefully and took a sip...and promptly spat it back into the cup.

"What did you do to it?" she asked.

"What do you mean, what did I do? The same thing I've been doing for the last seven years!"

"It tastes funny!"

"Like what?" he exclaimed. Beckett shrugged.

"I don't know. Not good." She tried to sound apologetic, but she was busy trying to wash the awful taste out of her mouth with a glass of water.

"Do you want me to make you another?"

"It's fine, I'll just drink this," she said, holding up the water. She went back to staring intently at the board. Castle subtly sniffed his latte, made just after Beckett's. He took a small sip and furrowed his brow. Definitely still tasted like the same coffee he'd been making her for the last seven years.

One week after the coffee incident Beckett still hadn't touched a cup of coffee. Castle had tried every different combination of coffee that he knew, and every time Beckett got close to the cup her nose would wrinkle in that adorably frustrating way and she'd shake her head. Finally he gave up and started bringing her the little bottles of Pellegrino that she had taken a liking to in the last week. Castle suspected something was up, so he started watching her a little more carefully.

They had been called into a murder scene that morning. Gruesome one, too. The victim had been bound and then skinned. He most likely died a painful death, and oh god, the smell. It nearly knocked Castle on his ass when they got through the door, but not Beckett. She cracked open her Pellegrino and inspected the body and the scene at every angle possible, trying to get a sense of what happened the night her victim died. The team had iron stomachs for this kind of mess, but even Esposito looked a little green by the time they had finished their preliminary sweep of the building.

When she and Castle got back into her cruiser Beckett pulled out a bag of beef jerky. Castle gagged.

"What?" she asked. She'd been testier than usual lately, and she didn't like the look he was shooting her as she ripped into the bag.

"Really? It looked like Hannibal Lecter chose his morning snack in there, and you pull out a bag of jerky?"

"I'm hungry!"

Castle was tempted to point out that they'd eaten breakfast only an hour ago, but his extensive experience with women had taught him that that was never a good idea, so he took another route instead.

"You hate jerky!"

"I don't know Castle, what does it matter? I wanted something salty, and this was the only thing I could find in the cupboard."

He shrugged and chose not to pursue it. Beckett was already gnawing on a strip of the dried beef. Castle desperately wanted to open the window and let a little fresh air in, but he didn't want to incur her wrath. He kept the window closed, breathed through his mouth, and they buckled up their seatbelts and headed into the precinct.

Two days later, Beckett sat at her desk rubbing her temples, trying to get rid of the awful headache that had struck twenty minutes earlier. Castle was out making a quick corner store run to grab some aspirin and Pellegrino for her.

"Ryan!" Beckett said. Both Espo and Ryan were across the room, and they turned to look at the detective.

"Yeah?" Ryan asked. They both moved closer, but Beckett held out her hand to stop.

"Are you wearing cologne?"

"Uh...yeah?"

"I think it's what's giving me this headache, can you go wash it off or something?"

Espo and Ryan shared an incredulous look.

"You could smell my cologne from across the room?"

Javi sniffed at Ryan for good measure. He was standing a foot away from him and could barely notice it.

"Just wash it off, would ya?"

Castle had watched everything from the break room, and he hid the aspirin in his pocket before heading back into the bullpen. He handed Beckett her water, which she accepted gratefully.

"No aspirin?" she asked, her head still throbbing.

"Sorry, they were all out," he lied. She nodded and took a huge sip of water. Beckett knew she'd be counting down the minutes until she could get out of the precinct that day. Castle saw Ryan looking a Beckett very peculiarly. The two of them made eye contact and Castle shook his head slightly. Ryan raised his eyebrow, and Castle shrugged slightly. Espo looked between the two of them like they were insane, and pulled Ryan away to the break room to continue their discussion on whether or not cheerleading was a real sport.

Castle and Beckett had to visit Lanie during their investigation because of something unusual she had found on the body. As Lanie was describing exactly what she found so unusual, she couldn't help but look at Beckett a little differently.

"What?" Beckett said as Lanie stared at her.

"Are you doin anything different?" Lanie asked.

"Like what?" Beckett said, confused. Lanie raised an eyebrow, and Castle quickly motioned for her to be quiet. Lanie raised her eyebrows.

"I dunno, your hair maybe, or something. Looks different." Lanie busied herself with her clipboard, and Beckett whipped around to stare at Castle. He tried to look like the picture of innocence, but that was usually his greatest tell.

"What is going on?" Beckett asked. Castle shrugged.

"No idea, what's going on? Something's going on?" he said, and cringed at his choice of words. This time it was Beckett's eyebrows that shot up.

"Oooookay..." she said, and walked out of the morgue, leaving Castle to trail behind her.

Later that day, Castle was making his regular coffee (none for Beckett, of course, but he had her Pellegrino chilling in the fridge) when Lanie cornered him. He turned and noticed she was close behind him and he jumped in surprise, almost spilling his coffee.

"She doesn't know?" Lanie demanded, surprised. Castle didn't try to deny it.

"Apparently...not," he said, "How do you know?"

Lanie rolled her eyes. "Please, it is written all over that girl's face. She must be mighty oblivious not to notice it herself."

"Yeah, well, she can be like that sometimes."

"Mmmhmm," Lanie agreed. "So, are you gonna tell her?"

Castle shrugged. "I haven't actually figured that out yet."

Before Castle even realized what was happening, Lanie had embraced him. "In any case, congratulations"

"Castle?" said Beckett from the door to the break room. Lanie and he broke apart, and he tried again to look innocent. "What's going on?"

"No idea, what's going on? Something's going on?"

Beckett rolled her eyes and stared at the two of them. Lanie put her hands up. "Castle was just helping me figure something out, I was thanking him."

"Like what?"

"Oh, you'll find out soon," Lanie promised with a wink. Castle just shrugged and left the break room to go stare innocently at the murder board again. Beckett huffed. She could feel something was going on right underneath her nose, but she was too preoccupied with the murder to even begin to fathom what. Reluctantly, she followed Castle out and hoped that they could solve the murder soon so she could do her own interrogation to him to try and figure out what was going on.

Later that week, Beckett had gone to dinner with her dad, so Castle had Martha and Alexis over to their loft for dinner as well. Martha and Alexis were entering just as Beckett was leaving. The three of them exchanged quick hellos and hugs, and then Beckett had rushed off to see Jim. Alexis was giving Castle a strange look as she went to hug him.

"What?" he asked as he pulled her in tightly.

"Dad, is Beckett..." Alexis said. Martha looked on knowingly. Castle sighed.

"Yeah," he said.

"But...she didn't say anything," she said.

"Yeah, she doesn't know," he said.

"How could she not know? Is that even possible?" Alexis asked.

"Oh for goodness sake, it's Katherine Beckett we're talking about here!" Martha said. "That girl could find a needle in a haystack when it comes to solving crimes, but we all know what she's like in her personal life. She couldn't pick up a hint if it was dancing naked in front of her."

Alexis giggled at that, and Castle rolled his eyes.

"Well, in any case, I think this calls for a celebration! Richard, where's the wine?"

They toasted in celebration, and sat down for their meal. An hour later, Martha's cell phoned pinged. Her laughter bellowed through the loft when she saw the message, and Castle and Alexis both turned to stare at her.

"It's Jim," Martha says, "He wants to know how on earth Beckett hasn't figured it out yet."

"Did he tell her?" Castle couldn't figure out if he was relieved or irritated that Jim may have ruined the surprised.

"Oh no, sonny, he's leaving that to you."

A little bubble of anxiety rooted itself in Castle's stomach.

"Excellent," he said, with only the barest hint of sarcasm. He took a long sip of wine, contemplating exactly what his next move would be.

Two weeks later, Castle, Espo, and Ryan found themselves staring at Beckett's desk. This time, all three of them had their heads cocked like curious puppies.

"She's...sleeping," Espo said.

"Yeah," Ryan and Castle said at the same time.

Katherine Beckett was currently passed out on top of a stack of paperwork. Castle was almost certain he could see a little drool puddle forming on one of the papers. He hoped it wasn't terribly important.

"She looks so peaceful," Ryan said. At that moment, Beckett started snoring. "Or not."

"Seriously, bro. Is she like this every night?" Espo asked. Castle raised his eyebrow.

"Recently, yes."

"How do you sleep with that?" Espo said, cringing as Beckett emitted a rather loud snort. Castle glanced around. Other detectives were starting to stare.

"Y'know, Jenny used to do stuff like this when she was-"

"Yeah, I know," Castle interrupted Ryan, "Meredith was the same."

"What?" Espo asked.

"How're you going to tell her?" Ryan asked.

"Tell her what?"

Ryan and Castle both turned to stare at Espo. He crossed his arms, looking defensive. "What?" he said again. Castle ignored him.

"It's just...I've never had to deal with something like this before. How do I go about telling my wife that she's pregnant?"

"Dude! Beckett's pregnant?"

Ryan and Castle shushed Espo, and the three of them all turned back to stare at the sleeping detective.

"Y'know, last time Jenny was pregnant, I told her I had to work on a Saturday we were supposed to be going on a spa retreat, because her mom agreed to babysit Sarah Grace for the weekend, and she threw a hairdryer at my head." Ryan rubbed his head sympathetically, remembering.

"Yeah, I caught Beckett crying over the empty dryer sheet box yesterday." The boys all snickered. "But she threatened to shoot me if I told anyone, so that secret goes to your graves."

"I can't believe she hasn't figured it out yet," Ryan said. Castle nodded in agreement, but he knew how oblivious Kate could be to her own wants and needs especially when work was particularly stressful.

"You know," said Gates from behind the three of them. They all jumped and turned, trying to hide Beckett from Gates' view. "I found out I was pregnant when my partner at the time stopped for a hot dog, and the smell had me sick all over the inside of the squad car."

The three of them cringed at the image.

"You'd better get your wife home, Mr. Castle. And find a way to break it to her gently, will you? I have a feeling that Detective Beckett's going to be in for a real shock."

"Uh, yes sir," he said, surprised at Gates' leniency. He went to go wake Beckett up, but before he could, Gates stopped him.

"And, Mr. Castle? Congratulations."

There was warmth in her voice when she said it. The three of them gaped as Gates walked back to her office. Castle was surprised at the Captain's kindness. If he knew that was all he had to do to get Gates to like him, he would have knocked Beckett up sooner.

"Good luck, bro," Espo said, and Ryan nodded in agreement. Castle thanked them, and went to go wake up his wife and take her home.

May be slightly AU, as I'm not sure if it's ever been mentioned that Gates has any children, so please forgive me for that. Review? ;-)