Disclaimer: I do not own Castle, only my OC, Leanne.

Castle – A Chance Meeting

Chapter One:

Kate Beckett smiled as she stood in line with her sixteen year old adopted daughter, Leanne Beckett, and her best friend, Madison Queller, to get their copies of Storm's Break signed by the author, Richard Castle. "Mom, I, erm, I…" started Leanne, blushing slightly. Kate smiled at her and said "You need to use the ladies room?" Leanne nodded, making Kate smile before she looked at Madison. "Mads, can you keep our spot for us?"

"Sure thing, Becks." said Madison, with a smile. Kate smiled and turned to look at Leanne before saying "Come on, Annie, I need it as well." She led Leanne out of the line, slipping under the ropes.

As they reached the restrooms, they heard footsteps, fast footsteps. Both of them turned in time to see a five year old with long red hair running towards them. And trip over her long dress. Leanne managed to catch her before she could fall to the floor. "Hey there sweetie." said Leanne, with a smile. "Where're your parents?" Kate was scanning the room, as they both heard a male voice say "Alexis, sweetie, what have I told you about running off?" from behind them. Both of them turned to see a very familiar man standing there. "Sorry Daddy." said the girl, Alexis, not looking him in the eye. He smiled at her and said "It's alright, sweetie. Just don't do it again." He then turned to look at Kate and Leanne. "I'm sorry about my daughter. I'm..."

"Richard Castle, yes I know…" said Kate, with a smile. "My daughter and I love your books…" Castle smiled as he said "It's always nice to meet my fans."

"Daddy…" moaned Alexis, looking at him. "I need the big girls room…" Castle nodded and said "Alright sweetie, do you want me to come in with you or…"

"I'm a big girl, Daddy." she said, looking at him. "And you're a boy, you can't come in there, silly."

"Of course, silly me." said Castle, looking at her. As Leanne said "If you want, Alexis, I can come in with you. I need to use it as well." Alexis looked at her and nodded, before saying "Daddy?"

"Sure sweetie." said Castle, looking at her. As Kate looked at Leanne and said "Are you sure, Annie?" Leanne nodded, as she took Alexis' hand and led her into the ladies room. Castle smiled and said "So, you know who I am, but I have no idea who you are."

"Kate Beckett." said Kate, with a smile. Just as her phone went off. She sighed as she pulled her phone out of her bag and looked at it. "It's work, I need to take this." she said, looking at Castle apologetically. He just smiled at her and said "It's fine, I'll wait here for our daughters." Kate nodded and said "Can you tell Leanne I'll be right back, she tends to worry." Castle nodded, as Kate walked off putting the phone to her ear with a "Detective Beckett speaking." Castle let out a small smile, before leaning on the wall, pulling his own phone out.

Moments later, Leanne walked out of the ladies room with Alexis, to see Castle looking at his phone. "Where's Mom?" asked Leanne, frowning. Castle smiled at her and said "She got a call from her work." Leanne took a deep breath, before saying "Oh." with a frown. As she felt Alexis pull on her sleeve and say "Thank you for helping me."

"It was no problem, Alexis." said Leanne, looking down at her. Alexis smiled, as she walked over to Castle. As Kate rejoined them and said "I'm so sorry, sweetie, but I'm going to have to go to the precinct. There's been a development in the case I was working." Leanne sighed but nodded, before saying "Can we stop by the apartment so I can grab my laptop?"

"Sure thing, sweetie." said Kate, with a smile. As Alexis said "Daddy, can't Leanne stay with us?" Castle looked down at her and said "I don't know, sweetie, they barely know us OK…" Kate and Leanne shared a look, before Leanne smiled and said "If it's alright with Mom, I don't mind staying here. I can keep an eye on Alexis for you, Mr. Castle, if you want."

"Are you sure, Annie?" asked Kate, looking at her. Leanne nodded and said "Yeah, it beats sitting around the precinct." Kate nodded, as Castle said "I'll drop her off at the precinct when I'm finished here. If that's alright with us, Detective."

"That's fine." said Kate, with a small smile. Before walking over to Leanne and placing a kiss on her forehead. "Be good for Mr. Castle alright."

"I will, Mom." said Leanne, with a smile. "Go put bad guys behind bars. And don't forget to tell Aunt Mads you're leaving." Kate smiled back and said "Of course." She looked at Castle. "Are you sure this is alright?"

"It's fine, Detective, go and do your job." said Castle, with a smile. Kate nodded and walked off, and Alexis said "Leanne, can we go look at the books?" Leanne looked at Castle, who smiled and nodded, causing Leanne to smile as well before saying "Sure thing, Lex."

Ten minutes later, they were looking around the kids section of the book store. Alexis was looking through the books for six to seven year olds, while Leanne was looking through the younger kids books. "Hey Lea." came Madison's voice, from behind Leanne. Leanne turned and smiled at her, as Alexis made her way over. "Hey Aunt Mads." said Leanne, with a smile. Madison smiled back, as she noticed Alexis hiding behind Leanne's leg. "Who's this adorable little girl then?"

"This is Alexis." said Leanne, with a smile. As she looked at Alexis and said "Lex, this is my Aunt Madison." Alexis waved, sightly shy, before returning to the books she was looking at before. Causing Madison to smile before she looked at Leanne and said "Do you need me to stay or are you going to be alright?"

"I'll be fine, Aunt." said Leanne, with a smile. "I have Alexis to distract me if I get too bad." Madison nodded, with a small smile, before she said "If you need me just text me, OK? I'll be straight here." Leanne nodded and hugged Madison before saying "Of course, Aunt Mads." Madison smiled and said "I'll see you later, Lea." before walking off. Leanne smiled, as Alexis walked up with a My Little Pony book and said "Can I read this to you, Leanne?"

"Of course, Lex." said Leanne, with a grin. "Of course you can."

Alexis was sat next to Leanne while Leanne was reading the hardback of 'Justice League/Power Rangers' out loud, three hours later. "You're a comic fan, I see." said Castle, surprising Leanne. Leanne looked at him and said "Mostly just the Power Rangers ones, I have a soft spot for the TV show. And the comics are better than they have any right to be."

"So I hear." said Castle, with a smile. "I can buy that for you if you want, I don't mind." Leanne shook her head before saying "I… I already own it on my Kindle… I just wanted to read it again." Castle nodded with a smile before saying "OK then. My daughter wasn't any trouble?"

"She was a little angel, Mr. Castle." said Leanne, with a smile. "Lex was telling me about her week in California. She says she touched a shark."

"Ah, yes." said Castle, with a smile. "We went to an aquarium while her mother was at an audition." Leanne nodded, as Castle continued "And please, call me Rick." Leanne nodded, with a small smile. "Anyway, I'm done here. I can take you back to your mother if you want." Leanne let out a small sigh before saying "Sure." as she stood up. Alexis frowned as Leanne walked off to put the book away. Alexis looked at Castle and said "Can't she stay longer, Daddy? I like her." with her puppy dog eyes. Castle let out a small smile before saying "Sorry, sweetie, I promised her mother we'd take her to the precinct when I was finished here." Alexis pouted, as Castle continued "Do you want the books?" Alexis shook her head and began putting the books away. As Leanne returned, saying "Can we stop by my apartment first? I need to grab my laptop if I'm gonna spend the rest of the day at the precinct." Castle nodded before saying "I don't see why not."

Leanne let out a small smile as she opened the door to the apartment she lived in with Kate, to see Kate's boyfriend, Will Sorenson, sat at the kitchen counter reading a newspaper. "I thought you were at the precinct with Becks." said Sorenson, looking at her. Leanne let out a small smile before saying "I forgot to grab my laptop." as she shut the door. Sorenson nodded before saying "How was the signing?"

"It was alright." said Leanne, with a shrug. Before walking down the corridor towards her room.

She made sure to slip an SD Card out of the desktop computer sat in the corner of the room as she grabbed her laptop from the desk. Along with a shoulder bag. She smiled, as she heard a knock on the apartment door. And Sorenson shouted "I've got it, Leanne." Leanne smiled as she grabbed a change of clothes from the wardrobe which she placed into the shoulder bag along with the laptop and charger. She turned when there came a knock on the door. To see Sorenson standing there, looking confused. "Do I want to know why the author of the book you and Becks went to get signed is in our apartment with a little girl?"

"I told him to wait in the car." said Leanne, sighing. Sorenson looked at her before saying "You know him?"

"I looked after his daughter for a bit this afternoon when Mom got called in for a case." said Leanne, shrugging. "He's dropping me off at the precinct." Sorenson nodded, before saying "Fine. Can you tell your Mom I'll be stopping by about five, I'll even bring your favorite pizza." Leanne nodded as she grabbed her bag, before saying "Thanks, Will." and walking past him.

"I thought you were staying in the car." said Leanne, as she walked into the main room to see Castle looking at the bookshelves. Alexis was sat on the sofa, watching him. Castle looked at her as Alexis said "Daddy wanted to see your books."

"I see you've got all of my books." said Castle, with a smile. "Including some of my rarer ones."

"Mom's not gonna be happy you were snooping, Mr. Castle."

"I told you, call me Rick." said Castle, looking at her. "And I wasn't snooping, they're on display." Leanne laughed, as he said "Are you ready to go?" Leanne nodded, as Alexis hopped off the sofa.

Ten minutes later, they were walking out of the elevator onto the homicide floor of the Twelfth Precinct. Kate was stood at a whiteboard with a dry marker in her hand. "Need a hand, Detective?" asked Castle, looking at her. Kate turned and smiled as she saw the three of them. "I'm good, Mr. Castle." she said, looking at him. Before looking at Leanne. "I see you've been back to the apartment."

"I told him to stay in the car but he wouldn't." said Leanne, looking at her with an apologetic smile. "He saw the books." Kate let out a small smile before saying "That's alright, Annie. Was Will home? He sent me a text earlier mentioning that he finished his case."

"Yeah, he told me to tell you he's coming by at five." said Leanne, with a small smile. "He's bringing my favorite pizza." Kate nodded, with a small smile of her own. As Castle asked "What's wrong with pizza?"

"Nothing's wrong with pizza, Mr. C… Rick." said Leanne, looking at him. "It's just he only buys my favorite when he's trying to butter me and Mom up for something." Castle nodded, as Kate said "Leanne." sternly. "We'll talk about this later." She turned to look at Castle. "Thank you for bringing Leanne here, Mr. Castle." Castle smiled before saying "My pleasure, Detective. And like I told your daughter, call me Rick." He turned to the whiteboard with a smile. "So this is what a real murderboard looks like." Leanne smiled, she recognized the expression Castle had. "Hey Lex, I have a few episodes of My Little Pony on my laptop, I have a feeling the whiteboard has sucked in your father." Alexis grinned, and let Leanne lead her into the break room.

It was almost an hour before Castle appeared in the break room, to see a sleeping Alexis lay against Leanne, who was tapping on a laptop, as they lay on the sofa. "I am so sorry, Leanne, I didn't mean to leave you with her again but…"

"The murderboard is hypnotic." said Leanne, with a smile. "It's alright, Rick, I had some episodes of My Little Pony on my laptop. It's a good show."

"Thank you." said Castle, with a smile. "How'd you know I'd be a while?"

"You got the same look in your eyes that Mom gets whenever she sees the murderboard." said Leanne, sitting up. As Alexis started to stir. "Daddy?" she asked, sleepily. Castle smiled as he picked her up and said "It's me, Lex, let's get you home. It's been a long day."

"Not tired." muttered Alexis, leaning against Castle's shoulder. Before looking at Leanne. "See 'gain?"

"That's up to your father, Lex." said Leanne, with a smile. "I'd love to though." Castle smiled and said "I will set something up with your mother, we've already exchanged numbers." He looked at her as she said "I look forward to it, Rick. See you soon, Lex." Alexis waved as Castle walked out of the break room, at the same time as Esposito walked in. "So, I see you've made a friend." he said, looking at her with a smirk. "And she's the daughter of your favorite author."

"Shut up, Uncle Esposito." said Leanne, with a smile. "I was helping Rick out by looking after her while he was busy at his signing." Esposito smirked as she stood up, putting her laptop into her bag and walked out.

"So, did Rick help?" asked Leanne, as she sat down at the chair next to Kate's desk. She looked over at the whiteboard, with a smile. "He gave us some half-baked theories, but mostly asked us about procedure." said Kate, looking at Leanne. "How was his daughter?"

"She's adorable." said Leanne, with a smile. "And amazing. She was telling me about how she saw sharks in California. Her and Rick went to an aquarium…"

"Sounds like you're smitten, Leanne." said Kate, with a playful grin. "You like her."

"She's how I always imagined my little sister to be…" said Leanne, with a small smile. "If I ever had one, anyway." Kate nodded, before saying "Why don't you get yourself set up on your desk, Will will be here soon." Leanne nodded, and took a seat at the desk opposite Kate's. Pulling her laptop and headphones out of her bag.

At five, Leanne was sat at her desk, tapping away at her laptop with headphones on. Kate was sat opposite, talking on her phone, when the elevator opened and Sorenson walked out, holding three pizza boxes. "Thank you for that, I will get back to you when I have more information." said Kate, with a smile, as she put the phone down. And tapped Leanne's desk, motioning with her head behind Leanne. Leanne took her headphones off and turned, to see Sorenson walking towards them. "Hey guys." he said, with a smile. "I hope you're hungry."

"Starving." said Leanne, as she stood up. Kate did the same, and the three of them made their way into the break room.

Leanne smiled as Sorenson placed one of the boxes in front of her, as she sat down on the sofa. She opened it to grab a slice of pizza with pepperoni and sausage on it. "Thanks, Will."

"No problem." said Sorenson, as he placed the other box on the table he and Kate had sat down at. Kate smiled as she opened it and pulled out a slice with only cheese on. "So, you got the promotion." she said, after she had bit into it. Sorenson nodded and said "I move to Boston at the end of the week." He smiled. "I've already spoken to the Boston PD, they'd love to have you there…"

"Will, I'm not moving to Boston." said Kate, looking at him. "I just made detective, and Leanne has her whole life here. I'm sorry, Will, but it's just not gonna work." Sorenson nodded, before saying "I kinda figured." He stood up, kissing her on the cheek. "I'm gonna go pack my things, see you around, Becks." He walked out, leaving Kate speechless.

There was silence for a good ten minutes before Esposito walked in and went to swipe a slice of Leanne's pizza, which was already half gone. She slapped Esposito's hand away before saying "Mine. All mine." with a glare. Esposito put his hands in the air and said "Sorry. I guess I'll settle for plain cheese."

"It's how they do it in Italy." said Kate, being brought of her shock. Before looking at Leanne and saying "What have I told you about sharing?"

"Not my pizza." said Leanne, looking at her. "No sharing my pizza." Kate sighed but stood up. "Eat up." she said, looking at Esposito. "Then I want everything you've managed to find on Heywood's dealings with the mob." She walked off, as Esposito nodded and grabbed a slice. Before he turned to look at Leanne. "Was that Sorenson I saw walking into the elevator?"

"Yeah." said Leanne, between bites of a slice. "He got the job in Boston and wanted us to move out there with him. Mom said no. He's moving out and I think they broke up."

"Huh." said Esposito, nodding. "Are you alright? I know you liked Will."

"I'm fine, Uncle Espo." said Leanne, with a smile. "I got my favorite takeout pizza out of it." She finished off the slice and immediately grabbed the next one. Esposito smiled and said "How's many that now?"

"This is my sixth, just two left." said Leanne, with a grin. Esposito chuckled before saying "I don't know where you put it all…" and walking out.

"Kate Beckett's phone." said Leanne, after she had grabbed Kate's phone from the desk as it rang, later that night. She smiled when she heard the familiar voice of Castle say "Leanne? Why are you answering your mother's phone?"

"She's interrogating a suspect." said Leanne, with a smile. "I'm currently at her desk."

"You're still at the precinct?" he asked, confused. "It's, like, nearly midnight."

"Mom got a lead and I don't like being at home alone, can never sleep till Mom gets back." said Leanne, shrugging. "Is everything alright? Why are you ringing?"

"Everything's fine, Leanne." said Castle, making Leanne smile. "Listen, I was calling to ask your mom when you're free for a playdate. Alexis just went to sleep and she's been asking all day to see you. Are you free tomorrow?"

"I'm always free, Rick." said Leanne, with a small smile. "Why?"

"Alexis and I are going to the museum to see the Dinosaurs." said Castle, sounding giddy. Leanne smiled, before saying "It's Mom's day off you know."

"Is that Castle?" asked Kate, taking a seat in her chair. "Why does he need to know my day off?"

"He's invited us to the museum." said Leanne, looking at Kate. "Can we go?" Kate smiled and said "Hand the phone over then go and say goodbye to the captain, we're going now." Leanne nodded and passed the phone over before standing up and walking off. As Kate said "What's this I hear about a museum trip, Castle?"

Kate smiled as she poked her head into Leanne's room in their apartment, an hour later, to see Leanne sat at her computer. Typing away at the keyboard. Her laptop was on the desk next to the screen, and it was on. "Hey sweetie." said Kate, looking at her. "Can I come in?" Leanne looked up at her and smiled, before saying "Sure." Kate smiled and walked in, sitting down on the bed. "You looking forward to tomorrow?"

"Yeah." said Leanne, with a smile. Before looking at her. "You'll be there all day, right?"

"I'm on call, but I've told Esposito and Ryan to only call me if it's important." said Kate, with a smile. "I'm all yours tomorrow, promise." Leanne nodded, with a smile. Kate stood up and said "Don't stay up too late, OK?" Leanne nodded, as Kate placed a kiss to her forehead. "OK Mom." said Leanne, with a smile. "I'm almost done here anyway." Kate nodded, before walking towards the door. She stopped at the door. "I'm going to bed now, night."

"Night Mom." said Leanne, with a smile as she grabbed her headphones. "Love you."

"Love you too." said Kate, with a smile. "Remember, busy day tomorrow, don't stay up too late."