I'm back again! And NO, I haven't given up on "Fullmetal Detective"… it's just been so long since the last time I put any real effort into it, that I needed a little something else to get me back into the writing groove (not to mention I'm still stuck in exposition mode over there). So here we have another crossover, and as with my House fic, those of you who know me well should know this was coming. Believe me, it's a lot sooner than I thought, too – we're only 1.5 seasons in, and I'm already delving into it.

Anyway, without further ado, here's "April Showers Bring… Outside Help?"

~*~

Chapter 1

Richard Castle and Kate Beckett crossed the threshold into the small apartment which happened to be their latest crime scene. A quick scan of the room showed three forensic technicians inspecting broken objects and dusting for fingerprints. Esposito and Ryan were standing off to the side talking with a distraught looking woman who the writer and detective both determined from a quick glance was probably the victim's wife. They crossed over to the bedroom door, and the officer overseeing the First Response team made space for them to go in.

The bedroom was a mess of broken objects too. They stepped gingerly around mirror shards and broken light bulbs, to see how the body had been found. Castle saw something on the floor that attracted his attention, while Beckett observed that the victim was a middle-aged man who was slumped over his desk. The techs rolled him over to expose a knife wound in his belly. They also picked up his hand to show her a bloody finger. She looked back to the desk, where she was now able to see the dying message he had written.

Esposito and Ryan wrapped up their conversation with the grieving wife, and joined Beckett at the desk in the bedroom. "The victim is 41-year-old Haru Inoue," Esposito explained. "The wife says she was at her parents' the last few days, and has no idea how this could have happened."

"Get a list of the places she went while she was there, and check them out."

"Sure thing."

"Hey, check this out," Castle said, displaying what he had found. "Matchbox cars! These things were huge twenty years ago… no pun intended. That's an odd thing for a man his age to have lying around."

Beckett was about to tell him to stay on track, when she noticed what else was on the floor behind him. There was an extensive set of dominos, tubes, tracks, cords, pulleys, and marbles arranged with the intent to accomplish something. "Or perhaps this was the weapon," she mumbled.

Ryan picked up the dying message from the desk, and held it with the writing facing away from him. "Anyone know Chinese?"

Castle looked at it. "Nope. And actually, that's not Chinese, it's Japanese. See these complex characters? All of Chinese is like that. In Japanese, some of the writing is expressed by individual syllables, like these simpler characters."

"Okay… Does anyone know Japanese?"

Castle answered again. "Nope, but I know someone who does." He whipped out his cell phone, found a name in his contact list, and placed the call. "Hi, Yuusaku-san? It's Rick Castle. I'm at a crime scene, and… yeah, yeah, very funny. Anyway, there's a note here that was written in Japanese, and I was wondering if you could come take a look at it. You're busy? That's a shame, it would have been great to see you. What? Oh, okay." He ended the call and turned back to the detectives. "He says he's a little buried in his writing right now, but he's sending someone else over."

'Another writer,' Beckett thought. With all the different circles Castle travelled in, one of his contacts eventually had to be a writer, and one who knew Japanese, to boot. "He write anything we've heard of?"

"Night Baron?"

"Mysteries… figures…" Beckett rolled her eyes and continued her investigation of the scene.

Ryan and Esposito stepped closer to Castle, to make way for her. "Yuusaku Kudo," Ryan asked. "Not only is he famous, but so is his wife."

"Man, she is hot," Esposito interjected.

Castle grinned. "I know. I hope she's the one he's sending!"

They heard raised voices coming from the direction of the front door of the apartment, and went back out to the living room. Castle assumed it was his guest having trouble being admitted into the crime scene, so he walked towards the door with his arms out. "Yukiko-san, it's been too…" He stopped short when the argument came to a crashing halt. The officer at the door, as well as a young Japanese boy and girl showed him a trio of blank stares. "You're not Yukiko Kudo," he said with a barely noticeable twinge of disappointment.

The boy held out his hand. "Yukiko Kudo is my mother. My name is Shinichi; it's nice to meet you." His friend was blushing furiously. "This is my friend, Ran Mouri."

"Hello," Ran said while Castle gripped Shinichi's hand.

Castle made a shallow bow. "Hajimemashite." This surprised everyone in the room, particularly the two teens. "Uh… don't expect much more, your dad only taught me a couple phrases."

"It's okay," Shinichi said. "It was very good pronunciation."

Castle beamed at the compliment. "Your English is pretty good too, I was surprised."

"May I look at the room?"

Castle looked at Beckett, who shook her head 'no'. There was no way she was about to let a teenager wander around her crime scene. Castle pleaded silently with his eyes. She was surprised at how easily she gave in to him. He turned to the kids and said "Yuusaku-san called you to fill in for him. If he trusts you, then so do I."

Shinichi was so excited to get started, that he was already half way to the box of latex gloves by the time Castle was finished speaking. He brought back an extra pair for Ran, and then started his own inspection of the apartment. Beckett was amazed at how professional he was being.

Ran bowed to Castle and Beckett. "Thank you."

"You're welcome," Beckett said.

Ran put on her gloves, and went to see what Shinichi was looking at. She noticed that he could tell from a quick walk around the living room that everything interesting about this particular case would be found in the bedroom. "Shinichi… if the primary scene is in the bedroom, why are the forensics guys all out here?"

"They probably think they got everything they could from the bedroom, and are just covering their bases."

"Oh, that makes sense." Ran wrapped her arms around one of Shinichi's. He blushed at the contact, but since he knew why she was doing it, he gently led her towards the main area of the crime scene. Once they were inside, she discovered that she was able to let go, and they searched the room for anything that looked like a clue.

Shinichi was immediately drawn to the same thing Castle had been upon entry. He knelt down and studied the intricacy of the apparatus. Ran found the note, and brought it over to him.

"Do you recognize this, Ran?"

"Yeah, it kinda looks like Pythagora Switch."

"That's right… I wonder why the killer would have set up such an elaborate mechanism just to kill a guy."

Ran held up the page with the dying message so Shinichi could read it. "I found this on the desk. It sounds…weird."

Castle and Beckett stood in the bedroom doorway. "Did you find anything," Beckett asked.

"Yes," Shinichi replied. "I definitely think this apparatus was part of the murder weapon. What I don't understand is why the murderer took the time to set it up, and what the dying message means."

"You mean to tell me you don't know what it says?"

"Oh, I know what it says. I just don't get why he would have written 'All I did was get out of the shower.'"

"Uh, guys," Castle interjected. "Where'd the body go?"

~*~

End Chapter 1

A/N: I figure the timing for this story is from those flashbacks when Shinichi and Ran were in New York, when they met Ms Vineyard the first time… even though that would have been in the mid-1990's, and Castle is set in the present decade, it seemed like the best opportunity to bring the two sides together.

"Pythagora Switch" is basically a Rube Goldberg machine, and is featured as part of Japanese children's tv programming.

The contents of the dying message are a reference to a popular Philadelphia morning radio show ^_^.