My first foray into the realm of Castle if you don't like it or if characters are not to your liking tough. This is a slight AU/Potential future fic for the upcoming episodes involving Beckett's boyfriend. There will be a second part and this is really just an idea that popped into my head. I got tired of seeing Castle always being the person beat up on so I decided to turn the tables. I did not have this betaed so any mistakes are mine and mine alone. I hope everyone enjoys!

I do not own any of the characters of Castle nor anything related to the show.

It had all began with Kate's introduction to Detective Tom Demming, their mutual attraction, and his subsequent partnering with their team for a duration of a case. Castle had to admit Tom was a nice guy, no question about it, he was charismatic, good at his job, great track record, all in all a guy everyone could be friends with. Honestly, while it was a bit of a sting to see Kate give in to Tom's charm while avoiding his like the plague he didn't even feel much jealousy over the two of them possibly being together. There was really only one problem with the entire situation that really irked Castle, and that was how he was finding himself quickly becoming the new fifth wheel during the investigation.

What did that mean? Well it was becoming glaringly obvious, to himself at least, that his once prominent and valued place as a member of the team was slowly eroding out from underneath him. Ryan and Esposito, who he designated as two of his close friends, still treated him the same ribbing, making jokes, and feeding the birds with him. However, he knew he would never really be a part of their crime solving partnership nor did he want to get in the way of their tandem, frankly it made them great and he knew from day one he could help compliment but never be a part of what they had.

No his problem currently were with Beckett and Detective Tom Terrific and how he had conveniently been edged out of his spot as her partner to make room for her current interest. Since the two of them got together he was ever faster feeling like he was the third wheel to their great partnership. Would he say it was jealously that was making him think these thoughts, hell yeah he would. One released novel, with a second coming shortly, and over a year later he had thought he had more than proven himself to the extraordinary Kate Beckett, in fact she had even said on more than one occasion that he was useful and she was glad he was around. Instead here he stood in the break room watching as the two of them were in the midst of building theory and discussing potential scenarios in front of the murder board.

Castle didn't forget how, not only a few weeks ago, it was Beckett complaining to him about how building theory was something they did and that she was a bit upset he did it with Special Agent Shaw. Talk about calling the kettle black. Only a moment ago the three of them were discussing their current case, a murder of a forty five year old single woman, when he had been dismissed to the break room. There he was standing with the two of them weaving one of his tales, which MANY people paid to read by the way, about how such a mid aged woman could have been in the wrong place at the wrong time when everything went to pot. Tom Terrific had let out a short bark of a laugh shaking his head at the apparent absurdity of what he was saying. Tom was new though so that really hadn't bothered him much, no it was Kate that topped off the situation. After seeing Tom's little outburst of mirth she had decided to follow it up with a condescending dismissal, "This isn't fiction Castle go get us some coffee while you return both feet to reality."

So here he was watching the two of them after making only one cup of coffee, designated to the sidelines and being all but useless while the two of them continued on like they hadn't just snubbed him. Maybe he was being to judgmental of the situation, and maybe Kate just had to find her balance, granted it had been a few days since the case started and this was another of many such instances, but still he was fairly confident she hadn't completely forgotten him.

Just as Castle was pulling himself together and ready to make another run at the murder board, being more cautious this time of course, Ryan got off the phone. "We got a lead on a few suspect off the corner of Fifth and Lexington, apparently she frequently took classes at a gym downtown around this time," he informed them grabbing his jacket.

Spirits lifted at the impending field trip Castle put down his coffee went to retrieve his coat and crowded in the elevator with the rest of the detectives. Granted he had to almost force his way in after Kate and her "partner" occupied the front, much to the amusement of Ryan and Esposito in the back, but he still made the elevator. Traveling down to the parking garage he exited along with the rest heading towards the squad cars.

"Kate we can take my car you drive," Tom said throwing her his keys as they, followed by Castle, took a left as Ryan and Esposito headed in the opposite direction. Coming up to Tom's car Castle immediately noticed a very large glaring problem. Tom drove an old Ford Mustang with bucket seats which meant NO back seats, and unless he sat in Tom's lap he wasn't going to fit.

Apparently Kate and Tom didn't recognize the problem as they both entered the car leaving him standing outside by himself. Starting the car Kate eventually looked up seeing him standing there, "Sorry Castle no room, hitch a ride with Ryan and Esposito they should be by in a sec."

Deflecting his hurt with humor he bantered back, "No worry Detective I didn't really want to sit on Tom's lap anyway." That statement earned him a headshake between the two in the car and seconds later they were peeling away out of the parking garage towards the Gym.

Turning to head in the direction Ryan and Esposito went he took three steps when he noticed that they were already out of their spot and heading towards the exit on the opposite side of the garage from them. Taking off in a run to catch them he saw them exit the garage as he picked up speed. Only a handful of seconds had to elapse as he, in a dead sprint now, ran out the exit quickly scanning to the left and the right. Unfortunately New York traffic was not on his side this day as he saw them rounding a turn and quickly breezing out of sight.

"Just great," Castle muttered to himself not only had he been kicked out of his spot in shotgun with Beckett, but he had been kicked completely out of the car as well. To top it off Ryan and Esposito had left without even knowing that he didn't have a ride to the scene. Figuring he could call them and get them to turn around he really didn't think his pride could handle the explanation so reluctantly he raised his hand to hail a cab hoping that he could not only find the place, but also get there before the four detectives were done canvassing it.

Forty minutes later, since it took him fifteen minutes to hail a cab, Castle finally arrived at the front doors of the gym. As time went on he really was feeling more and more like an intruder in their case not even receiving a single call asking where he was and why he hadn't shown up. Entering the Gym he didn't see any familiar faces so he started to head towards the back.

"I'm sorry can I help you?" a very large and well built man asked from the check in desk.

"Yeah sorry about that I am here with the NYPD I am sure you saw four detectives walk by earlier," Castle quickly explained hoping that the guy would just wave him past so he wouldn't miss anything.

"Can I see some identification?"

"Umm I'm not actually a cop I'm a consultant so I really don't have anything to show you. I am shadowing Detective Beckett I'm Richard Castle author of Heat Wave. Didn't anyone leave a note saying I was coming?" great on top of being late to the scene now he was reduced to trying to talk his way in so he could even see what was going on.

"Is that a comic or something? I am sorry Sir but this is a private club and unless you are a member or have the proper identification I can't let you pass, and I haven't been given any word to expect someone," ok apparently this guy wasn't much into reading, or any other types of mental stimulation based on his looks, it also didn't help that Castle was most assuredly forgotten.

Sighing in defeat he flipped open his phone only to see he had no service which prompted him to walk outside to make his call. Three calls later and three straight voicemails he realized that he wasn't going to be able to get one of them to come let him in. Typical he couldn't get in and now none of them had a signal to boot his day was really just getting worse and worse. Realizing there was no way he was going to be able to get past the incredible hulk short of buying a lifetime membership to the gym he sat down to wait for them.

Several magazine and thirty minutes later the four detectives finally returned to the reception area with Ryan and Esposito coming from one way, and Kate and Tom coming from the opposite side. Both upon seeing him sitting with a magazine stopped and looked at the other group.

"We thought he was with you," Kate said towards Ryan and Esposito clearly confused at the sight of Castle waiting on a bench.

"Why would your shadow be with us? We assumed he was with you like he always is," Esposito shot right back which was a good point by the way since he never went with the two guys when Beckett was around. Castle wasn't writing books based on them after all even though they had small parts.

Deciding he didn't want them talking over his head like a five year old he decided to enter the conversation, "Actually after you left me in the parking garage Detective I went to try and hitch a ride with Esposito and Ryan but they had already left. Since I didn't want to make them turn around I took a cab. Forty five minutes later after managing to make my own way here I find I can't actually get in without a membership or a police ID, and that no one left word with the desk that I was coming. So I have been sitting here waiting for thirty minutes since there isn't service in this place hoping someone would come to let me in so I can actually do what I came here to do." Now that he had said it all he realized it really sounded just as bad as he thought it did.

Now Castle never took pleasure in another person's discomfort as a general rule of thumb, but he couldn't help but feel a sense of satisfaction at seeing the look of guilt on Kate's face. After all she was the reason he just wasted about an hour and a half doing nothing. As she apologized and they all headed back to the precinct, with him riding in the criminal cage of Ryan and Esposito's cruiser how wonderful, his sense of satisfaction quickly dissolved when he came to the realization that Kate hadn't even thought of him and that while her feeling of a guilt was a small victory it was a hollow one. He just hoped that she would snap out of her haze and actually realize he was around before the case was over.

(BREAK)

A few days later Castle was feeling a bit better about the entire situation. Needless to say Kate made sure to take her car instead of Tom's so they wouldn't have the same mix up again, even though he had to ride in the back. Apparently his opinion was also worth being valued again as he contributed in their discussion of theory while studying the murder board. Contributed he guessed was a bit of an exaggeration since he felt more like he was being indulged at the moment, especially when he disagreed with Tom Terrific.

"I am telling you her trainer can't be our guy, it just doesn't make sense," Castle argued towards Tom who was his current opposition.

"Why do you think that he is innocent even though we have evidence suggesting otherwise?" Tom shot right back clearly annoyed by the author disagreeing with him.

"Why would her trainer of seven years suddenly snap and shoot her in her own apartment? I would never write it that way," he argued back not understanding how Tom would connect such an impersonal means of murder with a man who not only relished in his physical fitness, but also had a very personal connection to their victim.

"Well if you wouldn't write it like that he obviously can't be our guy. He had motive that was clear to see when we interviewed him. She had filed complaints about him to the gym and it would be easy enough for him to have seen who was having a problem with him. Apparently you missed out on that fact when you were busy sitting in the lobby because you couldn't get in," Tom finished with a smug smile. Ok it was official the thing he said about this guy being nice just got crossed off his list.

Turning knowing he would find support in Kate, Castle began. "Kate think about it why would a guy who is…" was all he managed to get out before he was interrupted.

"Tom's right Castle we see these things all the time you didn't witness the interview, and I agree that he probably knows who filed the complaints and it upset him," she cut him off clearly showing what side she took in the argument.

About to start in on another more detailed explanation of why they were wrong Esposito walked up before he could start.

"Beckett we got the Vic's yoga partner who wasn't there earlier in the interrogation room when you guys are ready to talk to her," Esposito said before heading away to converse with Ryan.

Grabbing a file Kate headed towards the room with Tom and Castle in her wake. Just as they were about to enter the room Tom held his hand in front of Castle stopping him outside the door.

"Whoa there buddy detectives only and unless you have a badge and a gun I haven't seen you can watch from the other side of the glass it's the rules," Tom Terrific stated as if reading from the manual.

"I always go in with Beckett when we question people," Rick stated a bit peeved this guy would try and stop him, he wasn't the one being shadowed Beckett was and it was her call.

"He's right Castle you shouldn't be in there since you're a civilian, and besides it would be too crowded with three of us in there," Kate said without giving him a second glance as she walked in with Tom following closely behind.

Entering the observation room Castle was officially pissed only half paying attention to what was going happening on the other side of the glass. He had understood that she was trying to build a relationship with Tom, and even though he was a bit jealous he was very supportive of the matter. As he became a third wheel to the pair of them he shrugged it off as her trying to find the balance and being excited by their new team member. Now it was quickly becoming clear that he was just being indulged like he was the right after he signed his waiver, he was the writer shadow that didn't have any right to be there and they were the detectives doing the real work. So much for him making the cases more fun or him actually being "surprisingly useful" it was hard to be useful when nothing he said was being listened to.

Just then a comment made on the other end of the glass caught his attention and he found himself hanging on each word of the interrogation. About fifteen minutes later he heard them wrapping up and he quickly exited the door to way for Kate to exit. As soon as she exited he metaphorically ambushed her, his anger forgotten in his excitement.

"It couldn't be the trainer I know who did it now!" Castle exclaimed sounding like a kid who couldn't wait to show his mom an A on a school paper.

"Yes the trainer her friend basically just verified that for us, which you should know if you were listening," Tom said coming out of the room behind Kate.

"Still with the trainer thing you know you really have to stop being so stubborn it doesn't help the whole detecting process," Castle shot right back to high on his revelation to be brought down by Tom's remarks.

"Castle were you not listening she basically fingered the guy the case is closed I know you want to help, but stupid theories aren't what we need right now. You want to help get us some coffee and wait by my desk for me and Tom," Beckett said to him clearly annoyed.

In an instant Castle felt like he was just punched in the gut by a prize fighter. Never had Kate been so utterly short with him, and she had never refused to listen to one of his ideas before. Sure she would shoot some of them down as childish or outlandish, but she always listened before passing judgment. Castle would be the first to admit he could be a pain and sometimes got the team off track, but he always felt like he was capable of contributing and on numerous occasions was commended by the detectives for doing just that. Now he was being treated more of as a child instead of as an equal and it made his blood boil.

"Fine Detective I can see you made up your mind," he said knowing he couldn't keep the fury out of his voice completely. Kate though didn't seem to notice just nodding her head and turned to discuss something with Tom.

Barely able to keep himself from causing a scene he turned tightly and headed towards her desk seeing Ryan and Esposito staring at him with looks of sympathy. Walking towards Kate's desk he grabbed a piece of her stationary and began to write as Ryan and Esposito walked up to him.

"Bro, we just want to let you know we see what she's doing and it's not right man," Esposito stated.

"Yeah while she may be getting all cozy with the flavor of the month man we still like having you around and are willing to listen to what you have to say no matter how dumb it sounds," Ryan chimed in with support.

Castle having finished what he wrote folded it in half and slid it in between the keys of Kate's keyboard so it was standing up. Looking at the two detectives a small grin found a way to his face, "Thanks guys I know you have my back no matter what. I'm going to leave, apparently I can't actually help so I might as well get out of her hair."

With a fist bump to each of his friends he turned around and headed towards the elevator. As he passed the two detectives by the murder board he saw them leaning close laughing over something completely oblivious to the fact they were about to accuse an innocent man. As he stepped into the elevator he saw Kate looking at him past Tom's head with a questioning look in her eyes. Squashing what hope he might feel at her gaze he locked eyes with her, and without looking away he reached down and hit the button closing the doors of the elevator.

(BREAK)

Kate had been thrilled with her team's most recent case because it included Detective Tom Demming. Kate had met Tom during a sparring session and the two had hit it off right away, to say there was chemistry between the two of them was an understatement. Tom was assigned to assist their recent case since he was new to the department and had not been assigned a team himself yet. Working with him had turned out to be quite an interesting opportunity to get a better insight into the man.

Tom had been a huge help and Kate had learned that behind his good looks there was also a very intelligent mind, a playful flirtatious side, a sweet guy, and to top it off one good detective. Tom was a lot like her, a by the book kind of cop that she could relate to who thought in a very systematic way. While the two of them seemed to click right away when they first met, they really meshed on a case, often seeing the same things and coming to the same conclusions without having to speak almost. Working with him was a stark contrast to working with Castle.

Speaking of Castle she hadn't seen him since she noticed he went home early. Castle was a big boy though so she really wasn't worried about him. True she did feel some guilt over leaving him in the parking garage of few days ago and having left him waiting in the gym lobby as they questioned suspects, but that had been an honest mistake. She was trying to get to know Tom and she didn't have time to babysit Castle with a new officer on the team, if he couldn't deal with that he could sulk somewhere else. Castle's theories had started grating on her as time went on.

Normally the yarns he spun were quite amusing, but with Tom around she started to see them like he did, as annoyances. Finding killers was a serious business and there wasn't time to take breaks every now and then to listen to some overgrown child tell some fanciful tale of how someone could have possibly been murdered. Detective work was based in cold hard fact and having Tom around, a man who saw things like she did, just drove that point home further. Castle had his uses but during this case his uses were hindering more than helping.

Then again he did rightly claim that the trainer was not their killer which brought her to the present. Tom and Kate were sitting stumped in front of the murder board staring at it as they tried to find out exactly who could have done it. Previously, both had come to the conclusion of the trainer being the man who held the smoking gun, but after further inquiry they had discovered that he had an alibi, albeit an illegal one. Apparently the Vic's trainer doubled as a high class male prostitute and was with a woman the night their Vic was killed until about five in the morning. Initially he had claimed he was home asleep which prompted her and Tom to believe it was him, but under pressure of being possibly guilty he had cracked and told the truth. Following through with his client, and security footage of her apartment complex had confirmed that he was not their man.

That left them back at square one and somehow Castle had seen it the entire time. She vaguely remembered him mentioning something as they exited the interrogation room around noon that day, but she couldn't really remember anything besides him trying to feed them another story. Kate was tempted to call him, but she figured if he knew something important he wouldn't have left early and would have definitely told her about it. So here she was about six hours later with her and Tom having nothing to go on both having come to the same dead end. Ryan and Esposito had left with Knicks tickets and she wasn't about to pull them away from a night they had both looked forward to for weeks. She had tried bouncing ideas off Tom but he was so similar in thought they didn't actually create anything new.

Sighing in defeat she looked at Tom, "I am out of ideas how about we call it a night and see if we can think of anything tomorrow."

Tom hearing this snapped out of his own thoughts and a smile formed on his face, "Sounds like a good idea to me. I'm starving how about we grab some dinner?"

Nodding her head Kate was glad for the invitation, "Let me grab my coat," she said as she headed towards her desk. It was funny she just realized she hadn't been to her desk since she got in today.

Once she got to her desk and grabbed her coat she noticed a note folded in half tucked into her keyboard with Detective Beckett scrawled on the front in Castle's handwriting. Sighing at another one of his childish antics and giving Tom a look as if to say how typical she opened it figuring it was some small dumb thing. Giving it a quick glance she studied it closer once realizing it was a serious letter and not something immature.

Detective Beckett:

Since you apparently did not deem my opinion very worthwhile during this case I decided that a written letter would be more successful in garnering your attention. Specifically, I want to address the identity of the killer of our victim. I understand that you and Detective Demming believe it to by the personal trainer, but however you are both wrong. Our trainer had an intimate connection to our victim and combining that with his sense of pride in his physical stature a more personal method such as strangulation would fit the cause of death if he was the guilty party.

Your notes indicate (which I trust since I was not present) the yoga teacher claimed he did not know the victim outside of class, but her yoga partner claims she took private classes with him. Plainly one of the two is lying and at this point I cannot be certain. If I was writing the story I would have the yoga instructor have a physical obsession with our victim and after a rebuff in the privacy of her home he returned later to exact vengeance, but that is just my stupid theory and probably wrong. Good luck finding the killer.

Richard Castle

Kate was stunned and had to reread the note over again not breathing the entire time. Castle had written this note before he left over six hours ago. Between now and then her and Tom had ran into dead end after dead end without any success, and the entire time her possible answer was waiting for her right on her desk. Over and over she had brushed Castle off thinking that he was just seeking attention now that Tom was on the team, but in reality he had been trying to help solve the case.

Just then with absolute clarity the image of Castle standing in the elevator leaving flashed through her head. Instead of seeing a sulking man upset because he wasn't getting any attention she interpreted the true meaning behind his gaze, fury. Castle had left furious with her… O God what had she done?

Next time Kate tracks down Castle to have a chat.

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