My exams start next week so I needed something to do to relax and since I've got writer's block for my story All Fall Down I'm working on this.

This is my first crossover of any sort so reviews would be appreciated. Enjoy :)

P.S. I might change the the title since I'm not totally happy with the one I've got.

"Who's our vic?" Beckett asked, walking under the crime scene tape then holding it up for Castle who was following close behind.

"Colonel Martin Sumner. He's a marine," Esposito answered, handing her his wallet and navy ID.

"Oh brilliant," Beckett said, her voice dripping in sarcasm, "That means NCIS need a call."

"Or not," a voice said from behind them.

Castle and Beckett turned in complete sync, with Esposito about a half second behind them. They were met by the sight of four people in NCIS caps standing at the end of the alley, their side of the tape. The man in front had grey hair and was obviously in charge, slightly behind him stood a geeky looking guy who was taping away at his phone. The rest of the team, a man and a women, were stood further back and were arguing about something and by the looks of it the women was getting annoyed while the man just looked like he was having fun.

The grey haired man walked forward and said, "Special Agent Gibbs," he introduced himself then gestured behind him, "Guy on the phone is Special Agent Timothy McGee and the two arguing are Special Agents Ziva David and Tony DiNozzo."

Beckett was silent for a moment then said, "Nice to meet you, I'm Detective Kate Beckett, that's Detective Javier Esposito," she pointed over at Esposito, "ME Lanie Parish," Lanie looked up and smiled before going back to the body, "And this is my partner Richard Castle."

Castle reached out his hand and Gibbs shook it.

McGee looked up at the mention of Castle's name and walked over, "The Richard Castle? The author of Derek Storm?"

Castle nodded and smiled, "And Nikki Heat of course."

McGee nodded, "I'm a big fan," he looked over at Beckett and said, "So you must be the inspiration for Heat."

Beckett nodded, by now she was used to people pointing out she was Nikki Heat, although she still wasn't completely happy with that name.

"Yep the one and the only," Castle said with a smile, before continuing, "So you like my books then."

Before McGee could answer Beckett turned to Castle and said, "Crime scene Castle."

"Yep sorry," he looked at McGee, "When the lady says zip it I do, or she threatens to shoot me."

Behind them they heard Lanie and Esposito snort but neither said anything and Beckett glared at him.

Before anyone could say anything else Ziva and DiNozzo walked over, "Is it him boss?"

Beckett spoke up before Gibbs could answer, "Not that I don't appreciate one less phone call to make, but how the hell did you get here without us ringing you?"

"We've been following Sumner for a few months," Gibbs answered, "He's suspected of smuggling drugs on ships then using gangs here in New York to distribute."

"What gangs?" Beckett asked the older man.

"One of the local biker gangs."

Beckett nodded then looked between the agents and the dead body, "So you're crime scene?"

To everyone immense surprise, especially his teams, Gibbs shook his head, "No, I know who you are detective and I think we can help each other."

Then DiNozzo spoke, "How the hell do you know her boss?"

He looked over at DiNozzo and then back at Beckett, "Fornell was telling me about a case that the FBI ran with the NYPD about a crazy stalker after Nikki Heat and I heard about the dirty bomb they defused."

"They did what?" Ziva asked, sounding a little shocked.

"They defused a dirty bomb set to go off in the middle of the city with seconds to spare," Gibbs answered in a calm tone.

Ziva looked at Beckett and said, "Detective, I'm impressed."

Beckett shook her head, "Wasn't me, was him," she said, nodding at Castle, who was watching them talk.

He shrugged, "I got lucky."

Esposito laughed behind them and Ziva and DiNozzo looked at him, questions in their eyes. Esposito looked between Castle and Beckett and then answered their unanswered question, "He yanked out all the wires just as the timer ran out."

"And you're still here?" McGee sounded shocked, and from the looks on DiNozzo's and Ziva's faces they felt the same way.

Beckett and Castle looked at each other and gave each other a private smile before Castle turned and looked back at the NCIS team, "We tend to have good luck. I think that case we should have died what was it," he looked at Beckett, "Three times?"

Beckett nodded, "Yep, gun, freezer and the bomb." As she spoke she counted off on her fingers.

DiNozzo, Ziva and McGee all looked shocked and like their jaws were about to drop, even Gibbs looked slightly shocked by what they had said but he hid it better.

"Yeah, yeah," Lanie said, rising from her kneeling position by the body and moving to stand by Esposito, "You two should have died about twenty times and you save each other. We all know you never talk about it so zip and do some work."

Esposito stood beside her, his mouth slightly open, taken aback by what his girl had just said to her best friend and in front of guests.

"Ma'am yes ma'am," Castle muttered under his breath.

Beckett smiled and elbowed him in the ribs, "Shh, she can make it look like an accident."

Castle smiled back at her then turned to look at Lanie who gave the partners a glare them said, "My body or do you want to do the autopsy?"

Gibbs thought for a minute before saying, "Ducky has been saying he wants a trip, so would it be alright if he came and did the autopsy here. You can work together or whatever."

"Sure," Lanie said before kneeling back down by the body.

"Hey Esposito," Beckett said, looking over at the detective, "Where's Ryan?"

"He said something about dumpster diving with the unis to find an ID," Esposito answered with a shrug.

Beckett gave him a look and he visibly shrunk, "And I was just about to go tell him we don't need one since we know who he is."

He walked off and Castle couldn't help the chuckle that escaped. Beckett gave him the look she reserved especially for him and said, "Don't be annoying or I'll phone your mother and get her to take you home."

Castle gasped and said, in a wounded tone, "Detective you wouldn't."

Beckett managed to keep a straight face for all of a minute before she smiled. The NCIS team watched them with interest for a moment before DiNozzo asked, "So how come you two work together? I mean he's a writer."

"She arrested me and I stuck around," Castle answered with a smile.

Beckett sighed, "No, you got the mayor to agree to let you follow me."

Castle shrugged, "You'd miss me if I wasn't here."

Beckett didn't deny it just turned to the NCIS team and said, "So, do you know what Sumner was doing here?"

Gibbs nodded, "We're pretty sure he was meeting a contact." Beckett nodded and was about to say something when Castle pocket started shouting DAD DAD DAD.

He fished his phone out his pocket and answered it, "Hey pumpkin, what can I do for you?" he listened for a moment, giving an occasional grunt then said, "Sure, don't do anything I would do." He stopped talking and listened to the reply before saying, "I have no idea how I had such a responsible daughter. Love you too pumpkin." He hung up then turned back to the group, "Sorry, my daughter."

"She alright?" Beckett asked as he pushed his phone back into his pocket.

"Yeah, just wanted to tell me she was going out with Paige."

Beckett nodded, "Hope she has a good time," she turned back to the watching NCIS team and said with a small smile, "You'll get used to it. We're not a completely normal team. His fault," she pointed at Castle.

"Hey," he pouted, then shrugged, "Actually you're right."

The NCIS team looked between the two of them, Gibbs shaking his head while the other three smiled.

They've changed the review button and you know you want try it :)