a.n. So this chapter takes another left turn. Like the show, we're not going to get all the case details right away, instead it'll be spread out. So we'll be leaving the big case behind for a couple chapters before we get back to it. With this story, I'm enjoying the changes quite a bit, so I hope I don't go overboard. Let me know if you think I'm going over the top.

Disclaimer: I don't own Castle. I bought a T-shirt once, though.

xxxx

Previously…

"I'm scared about that too, Kate, but do we have a choice? Sure we could put it out of sight, out of mind, but eventually one of us is going to reopen the case. Whether it's for new information, or just because we can't stand not to, it will happen. And now we have each other. We can watch each other and make sure neither one of us gets too far into it."

Kate nodded, happy with that answer. She wanted to look into the case, if for no other reason than to get answers for Rick. He deserved to have answers. She wanted answers too, but she cared more about his justice than her own. That is the biggest difference between this time and my last life, Kate thought, Rick is finally more important than anything else, even myself.

xxxx

It had been a week since they had started their investigation into the case. They had spent several hours going through both cases files, but hadn't found anything that could connect the two murders. Kate was very concerned that the Coonan case hadn't come up yet. They'd already worked two cases that, if she remembered correctly, had happened after the Coonan case in her previous timeline.

She was worried that perhaps that case wouldn't come up at all this time around, and would leave them with one less clue as to who could have committed the murders.

She and Castle had decided the night before to set it aside for a week before moving onto whatever their next step would be. They had spent the night enjoying each other's company and relaxing after a taxing week of work and extracurricular case work.

They had went to bed late, and had spent another two hours making love before falling asleep in each other's arms. Kate was woken from a particularly explicit dream by the ringtone on her phone. Groaning she picked the annoying device up from the nightstand and connected the call.

"Beckett."

"Yes, I'd like to report a murder," a male voice said over the line. Kate's blood ran cold. She remembered the case that had started out like this vividly, though she had been at the precinct when she had taken the call last time instead of lying in bed with Castle's arm possessively wrapped around her stomach. Another difference she noticed right away was this was not Scott Dunn, or at least it wasn't his voice. She'd never forget his voice.

Trying to keep her voice calm, Kate asked, "Do you have an address?"

"Where's the fun in that?" the voice asked.

Wondering how the hell she's going to get a trace when she's not at the precinct, Kate asked, "Okay, who is this?"

"Oh, I'm a big fan of yours Nikki."

"Uh, okay, tell me more about this murder then."

"I did it. That's about all you need to know for now."

Kate heard the phone drop from the man's hand. "Hello? Hello?" Cursing under her breath, Kate squeezed Castle's hand, hoping he was awake.

"Castle?"

"Who was that, Kate?"

"I need your phone, then go get ready, there's been a murder."

He untangled himself from her and grabbed his phone. Handing it to her he said, "That wasn't dispatch."

"No. It wasn't. I'll explain soon as I call it in, okay?"

xxxx

It took them an inordinate amount of time to get a trace on the still open phone call. Once they did, Kate discovered that the murder wasn't at Grand Central Station like it had been the last time, instead they found the body in the lobby of the main branch of the New York Public Library.

Walking around the scene, Kate saw that like the last time, the murder victim was a middle-aged male who appeared to have been shot.

"What do you have, Lanie?" Beckett asked.

"Name is Alex Peterman, lives near Dobbs Ferry. Wasn't a robbery. Business card says he's a personal injury attorney."

"Was he really killed at the library at six in the morning?" Castle asked.

"No. Preliminary time of death is right after the library closed at 9PM last night."

Kate turned to Esposito who had just walked up, "Do we know how the killer got into the library or why he waited until early morning to call it in?"

"As for the second question, no idea, but there are signs of a break-in near the rear entrance."

"How did no one hear the shots, I wonder?" Castle said, looking around. "Surely this building has security around the clock? And what about an alarm system?"

"They do," Ryan said, coming to stand beside Esposito. "The guard, however, was on the other side of the building most of the night dealing with taggers. The alarm system has been broken for over a month, but with budget concerns they haven't been able to get it fixed."

"Gotta love New York. Okay, do we have anything on the taggers?" Kate asked?

Ryan shook his head. "No, they kept coming back, but ran off before the guard could get close."

While the group finished at the crime scene, Kate pondered the differences this case had presented so far. She wondered why it was so different. She was almost positive that it wasn't the same person, Scott Dunn, as it had been before, but the motive seemed the same. What the hell is going on, she thought as she and Castle got into her cruiser.

"You said he called you Nikki?" Castle asked when she pulled out into traffic heading towards the 12th precinct.

"Yeah."

"So this might be some deluded fan who knows you're the one I based the character on."

"All we can do is work the case, Rick."

"I know, but I'm worried Kate. This just feels off to me. He's not going to stop at one, and if he has an obsession with you, he might come after you."

"I know babe, but it's not as if I'll go looking for trouble, and I'll be safe. I promise." She reached over and took his hand, giving it a reassuring squeeze.

xxxx

Despite the initial differences in the case, Lanie still found the word Nikki engraved on the bullets found in the victim. Also like the last time, she and Castle had been called into Captain Montgomery's office to talk about the case.

"Does he realize she's a fictional character?" Montgomery asked when they entered his office.

"Obviously he's delusional. But the character is based on Detective Beckett, so maybe he is confusing the two."

"What do we have on the forensics front," the captain asked Beckett.

"Given that the murder scene was a public place, CSU found thousands of fingerprints, many more fibers and a ton of DNA samples. It's going to take time, a lot of time, to get all that to go through. The guy on the phone told me it might be a month. Or two."

At that moment, as Kate was expecting, Ryan poked his head into the Captain's office and said, "Beckett, guy on the phone is asking for Detective Heat."

The group, including the captain, moved to Beckett's desk out in the bullpen.

"Beckett," Kate said, answering the phone.

"Hello, Nikki. Did you get the first part of my message?"

"Yes, I did."

"Well, then, good job! You'll find the second part is at the Central Park carousel."

Kate groaned inwardly, knowing exactly what they'd find on the carousel. The line went dead and she hung up the receiver.

She looked at Rick and said, "This is going to get a lot worse."

xxxx

After they had talked to Lanie about the body drop, Kate and her partner walked around the murder scene. The body was displayed on the carousel. The scene had been shut down, with cops all over the place. Kate kept her eyes out for any signs of anyone suspicious, remembering that they suspected the murderer had been at both the crime scenes observing the cops work.

After a brief look around, Kate turned to Castle and said, "It's not your fault, you know?" She knew that he'd be feeling guilty about this, and she didn't want him to dwell on something that he couldn't change.

"I know, but a little part of me doesn't believe it, and probably never will. And it will be worse if you get hurt by this bastard."

She stopped for a minute, grabbed his arm, and wrapped him in a hug. "I'm going to be fine, Rick, we'll get him. Alright?"

He pulled back and gave her a smile. "Alright." The couple were brought out of their embrace by several large black SUVs pulling up to the crime scene tape.

Kate groaned. "FBI is here." She had really hoped that Jordan Shaw wouldn't show up this time around.

Castle glanced over at her and smirked, "Either that or the President is due for a visit."

Before she could come back with a witty response, Jordan Shaw stepped out of one of the SUVs and started ordering her team to rope off a perimeter around the carousel.

"No way," Rick said, a big smile on his face.

"Wait, what? You know her?" Kate asked turning to look at him.

"Sure. Went to college with her, and she helped me a little on Alexis' case until she got pulled by her boss."

Well that's different, Kate thought snidely. Shaw walked up to them.

"Nikki Heat, I presume," was her opening line. So original, Kate thought sarcastically. She knew that she had to get her jealousy under control or she would risk another fight with Castle, which she could not afford to do.

"Kate Beckett, actually."

Shaw turned to Castle and said, "Rick Castle, I had heard you started shadowing an NYPD detective. How do you like it?"

Rick smiled, "Jordan. I love it. Sure does give me something productive to do, and the people I work with have been fantastic."

Controlling her blush, Kate asked, "You're going to take over, I take it?"

"Yes, but don't think of it as a take over. You'll be on the team. I've tracked this particular killer before, so I know his MO. Frankly, we're going to need all the help we can get."

xxxx

As before, the FBI invaded the 12th precinct homicide division. Kate and the boys watched as their home was swamped with high tech toys the NYPD could never afford, and dozens of people wearing suits that were bought from the same rack.

As Kate watched the invasion of her home, she knew that this case was going to be extremely different than it had before. She also knew that she had to stick close to Castle and that she needed to stay out of her apartment this time. The last thing she needed was to get blown up, or worse let Castle get blown up. What if the bomb is in Castle's loft this time, Kate wondered worriedly. She had no clue how to handle this situation. If there ended up being a bomb again, where would this new killer place it? Would they place it in her apartment? Or Castle's Loft?

Kate sighed and turned back to her computer. Whatever happened, she'd need to keep her eyes out. She couldn't lose Castle.

xxxx

Luckily for Kate, Castle seemed to have no romantic interest in Jordan Shaw, and he wasn't nearly as enthralled with her as he had been the last time around. That did wonders for Kate's jealousy problem.

They were currently in the War Room while Shaw's team ran finger prints and DNA from both of their crime scenes.

"We're running everything we got through all the databases we have access to," Shaw explained to Beckett and Castle when she spotted them in the room.

"I thought there was a backlog at the lab?" Kate asked.

"I have a Federal fast pass, so I get to jump the line. Currently we're running 30 or so leads that we found at both crime scenes. We're then putting it into a matrix to see if we have any evidence that ties the scenes and/or the victims together. We're also doing a matrix with what we know of both victims." She pulled up a grid with the information they had on the victims.

"The first victim, Alex Peterman and the second victim, Michelle Lewis, belonged to the same gym, but went to different locations. They were both members of MOMA and they both adopted cats from the New York Humane Society.

"What we're likely dealing with here is a male, mid-to-late-30s, obsessive in nature, but exceedingly intelligent. Most likely a college graduate, and it wouldn't surprise me to see him be an overachiever."

"It sounds like you admire him," Kate said, forgetting that she had said the same words in the previous timeline.

"I admire him the way Robert Shaw admired the shark in Jaws. The better I know him, the easier he'll be to catch."

Castle nodded along. "Same for writing a murderer, the better you can get in their head and understand them, the more realistic it comes across for the reader."

"Well this guy," Shaw continued, "seems to like public places, so he's a voyeur, and it wouldn't surprise me to find out that he likes to set fires, mostly because he'd love the attention. It could be what drew him to Nikki Heat in the first place. Her name. I have a few people going through Heat Wave to see if we can get any clues to what happens next."

xxxx

They were driving to interview on of the leads they had found, when Shaw asked the same question she had before, "So how long have you two been sleeping together?"

Kate blushed, "Is that really relevant?" Shaw didn't need to know about her relationship with Castle.

Castle, who was sitting in the back seat of the SUV just smiled, which Shaw caught out of the corner of her eye.

"You have something to say back there, Mr. Castle?"

"No, ma'am. I just knew that, as an FBI profiler, you're unlikely to let something like that go at face value."

"Well it wouldn't be very professional of me not to know who I'm working with. Will this be a problem?"

"No," they said together.

When they get to the suspect's apartment, Shaw said, "Okay, we're here. You stay in the car, Mr. Castle."

He nodded and then kept looking around the backseat of the SUV. While he didn't touch things like he had in her previous timeline, a part of Kate was happy that there was still that innate curiosity within him that had him observing his surroundings.

The females got out of the SUV, and as they were approaching the building's entrance, the suspect appeared around the corner, saw them and took off towards where they had parked the SUV. Unfortunately for him, he got too close to it and Castle opened the door and the suspect ran head first into solid steel, falling to the pavement unconscious.

Castle looked down at the fallen suspect, and back up at the two women then back to the suspect and said with a small smile, "I think he might have hurt the door."

xxxx

a.n.2. I know this is a little dry, but this is one of my favorite cases, so it's going to be at least four chapters worth of content, at least the way it looks right now. There will be some significant changes in store, some of which you can already guess at.

You'll also see Castle start to act more like the Castle we all know and love. His time with Kate, and is background work with the therapist will see a lot of things change during the rest of the story. He's going to get better, just like Kate did over the seasons in canon.

Please leave a review and let me know what you think!