Hey there, ready for a little Castle two-shots? Well, you better be. Actually, this story was meant to be a random funny one-shot, but it got a little more emotional than expected and there we are. I had to separate it in two. So, if you like the ending of the first part, just stop reading there. If not, the second part is a short scene between Ryan and Esposito, which is more humorous.

There no real spoilers in this story, but there's a little nod to Kill Shot (which is a great episode, right?). I know that the case is pretty random, it just popped into my head like that. *pop* And I hope that Kate is not too OOC in the beginning...

English is not my first language, sorry if there's any mistakes... :/

Disclaimer: I do not own Castle, or anything that you might recognize.

Hope you'll enjoy!

Be Happy

Kate stormed out of the interrogation room, violently slamming the door behind her. It startled Ryan and Esposito who were working at their respective desks. They both nearly had a heart attack. Getting over their emotions, they looked curiously at the scene unfolding in front of them. Kate walked to the whiteboard and began to move the photos in all directions and to write furiously everywhere she could. When she saw that her marker was running out of ink, she shook it and ended up throwing it on the floor as hard as she could. She groaned. Everyone in the room was staring at her for a few seconds but apparently she couldn't care less. Ryan and Esposito looked at each other, torn between laughing or running to shelter.

"Yo, Beck-" Esposito said cautiously.

"What?" she snapped. She turned around so that everyone could see the fire burning in her eyes. Esposito made a backward step.

"Um… What about uh, Dreadlocks over there?" he said, referring to her latest interview in the interrogation room.

"Wouldn't talk." Her eyes wandered again over the surface of the board. She played nervously with her fingers, then with her dad's watch. She sighed. "Nobody talks in this investigation. It's been five days."

"So, back to square one again?" Ryan joined in.

"I guess so."

Esposito looked around. "Where's Castle? Haven't seen him since last night."

"I don't know," Kate spat, and her face hardened. "I guess the murder of a Bob Marley fan isn't interesting enough for Mr. Best-Selling Author." There was no more doubt about it. Detective Katherine Beckett was pissed.

Esposito immediately understood. "Okay, I know what's going on… What happened between you two?"

"Nothing. Really." Seeing that she wasn't very convincing, she continued. "I swear. I'm just having a really bad day, and this investigation is going nowhere. Nothing to do with anyone."

Ryan and Esposito looked at each other, smiling. They were definitely not buying it.

"Nah, you're mad 'cause he didn't show up. C'mon Beckett, don't lie to us!"

"What? That's not-"

The noise of the elevator rang into the room. All heads turned to the familiar silhouette, slaloming between the desks and the officers with his cups of coffee.

"Hey guys! Sorry I was with Alexis, but I just realized something and…"

Castle stopped dead in his track. Kate looked like she was about to murder someone, and the two other detectives had a little idea of who it would be. Without saying a word, Castle held out a coffee cup to Kate. She almost snatched it from his hand. Taking a long sip, she finally relaxed a bit. But the tension kept building up until it became unbearable.

"We're going to search for things that…uh, you know, we might have missed," Ryan said, uncomfortable. He pointed their desks. "Financials and stuff."

Esposito walked past Castle and mumbled into his ear. "You should have seen what she did to that marker. Watch out, bro."

Castle watched as Ryan and Esposito sat silently to their desks. He gulped without exactly knowing why. Kate didn't even move. Her eyes were still focused on the board.

"So…" he trailed off. He didn't even know what he apparently did to make her this pissed! He squeezed his eyes shut, ready to receive anything. A slap, a punch, a marker… Anything.

She looked at him for the first time. She sighed again. "We're stuck." Kate placed a strand of hair behind her ear. There was still anger in her voice, but there was something else. Something that sounded like… despair? "If you have a wild theory or something, just go ahead. Nothing left to lose." She took another sip from her coffee.

Castle sighed from the relief. He put his cup on the nearest desk, smirking. "Actually, I have something even better. Do you remember the guy we interviewed last night?"

"Yeah, um… The victim's friend, the one he met on that Bob Marley forum. Alex Wyatt."

"Exactly. I've been thinking… He told us that his favorite Bob Marley song is Don't Worry Be Happy." Castle wore a horrified look. "I can't believe we let that one go unnoticed!"

Kate frowned. She sat on the desk in front of the board "What are you talking about, Castle?"

He scoffed. "Don't Worry Be Happy, that's not even a Bob Marley song! It was sung by Bobby McFerrin, way after the King of Reggae's death!" He paused, for the suspense. "Our guy is an impostor!"

Kate raised an eyebrow, glaring at her partner. She thought about what he had just said for a few seconds. And actually… "Well, I must admit… A Bob Marley fan worthy of the name would have known that for sure." And actually, she was maybe beginning to see the light at the end of the tunnel.

"Especially a fan that subscribes to a forum like that. Unless…"

Kate got up. She put her coffee next to Castle's and grabbed another marker. She removed the cap and wrote the name of the suspect under his picture. "Our victim, Marcus, had over a hundred thousand dollars worth of Bob Marley merchandise. Some of those things alone were rare and worth a fortune. Alex Wyatt knew about Marcus' collection. He told us that he would take care of all this stuff."

"That was suspicious."

Something that looked like a smile appeared on her face. She was once again completely oblivious to the stares of everyone else in the bullpen, including those from Ryan and Esposito. "So, Alex isn't a Bob Marley fan, but he somehow learns about the collection and he wants to know more about it."

"He subscribes to that forum, finds Marcus, chit-chats, and then…"

"He ends up killing him, planning to get the collection to sell it. Easy money." Kate bit her lip. "Okay, so… The story isn't perfect, but we've got a motive. We need to get Alex here."

"We're on it," Esposito called out before preparing to leave with Ryan.

Kate exhaled, her smile growing a little wider. Her eyes met Castle's. His blue eyes were shining, and she wondered if she'd ever get tired of staring into them, or just to see that look he had whenever they developed a theory together.

That was one of those things she could never tell anyone about.

"What did you say about us being stuck, Detective?" He said, wearing his most charming smile.

Kate looked away. She was blushing slightly. She placed the same strand of hair back behind her ear, fully aware that it was to gain time to reply. "I, uh…" She swallowed her pride. "I really thought that this was going nowhere. I mean, a song? The key to solve this case?"

"Not any song!"

"How so?"

"The lyrics are pure words of wisdom!" He grew closer to her. "In every life we have some trouble, when you worry you make it double," he murmured, quoting the song.

A genuine smile flashed on Kate's face but there was a hint of sadness that could be seen in her eyes. Castle was still smiling but he saw that she had something else on her mind and just waited for her to open up. Which she did almost immediately.

"Castle, that's..." She sighed. "My mother used to tell me that whenever I came home from a crappy day. She said it was from a song she liked. Sometimes those words would frustrate me even more, but most of the time it would just make me smile." She paused and her smile disappeared. "She kept telling me not to worry and just be happy. No one told me that since back then. Now I'm just… worrying."

Castle didn't know what to tell her, but he still managed to say something. It was the story of his life. "You shouldn't. You deserve to be happy, Kate."

That conversation began to sound awfully familiar to Kate. However, there was no way that it would end up the way it ended up the last time. "I know, I want to, but…" She looked down. "It's difficult."

"I know."

Kate chuckled. "Back then I didn't always care for what my parents had to say. Especially for those life lessons my mother would repeat over and over again. It's just with hindsight that I realized that… She was right. Maybe I should start listening to her." She laughed. Castle laughed too, not because it was necessarily funny, but only because it felt so good to hear Kate laugh.

"She was a wise woman." He said with a crooked smile. He was sincere.

"She would have liked you," Kate admitted, also sincere. "I'd have you meet her for sure. And while you'd be away, she'd probably tell me-" She stopped herself, looking a little disturbed. She frowned. "Uh, you don't want to know what she'd tell me."

"Why?" Castle teased. "Because it would be too… shocking?"

"Not really."

"Awkward?"

"That's more like it." Kate took a few seconds to think about it. About what she felt, about what she had been through. She thought about those things, the things she couldn't say or the things she didn't know how to say. She thought about happiness, how she was supposed to find it. How she needed to find it.

She just thought about happiness. And love.

She looked into his blue eyes. She felt the melancholy return. "My mother would want me to be happy. I have to be happy. I want to, really… But after all these years, I don't know if I can."

Castle put his right hand on her shoulder. He kept looking into her eyes. After all that she had been through, he just wanted to take her pain away. Though, after hearing what she had just told him, he felt like he was one step closer to being able to truly do so.

"You can." He replied softly. "Be happy, Kate. You deserve it."

A sad smile appeared on her face. She moved a little closer to her partner. "Thank you, Castle. For everything."

And his obvious answer to that was :

"Always."