Author's Note: well, the feeding of the plot-bunnies seems to have worked. this one has grown enough to be my first multi-chapter effort. woohoo! as usual, reviews welcomed.

Summary: After their heart-to-heart the day before, Castle and Beckett meet up for a workout the next morning, only to be interrupted. More to follow when I can get it written.


7:00am, 12th Precinct Gym

The two of them had started out with a light workout and some stretching, followed by ten minutes with the focus mitts, and another half hour with the kick-bag. Finally, they had shifted into sparring, and Castle had pushed her hard for close to quarter of an hour. Breathing heavily, Beckett snapped a low kick and retreated several paces, her guard up, muscles burning with fatigue. A predatory grin on his face, Castle closed the distance rapidly, his torso covered in a light sheen of sweat. Two quick jabs to her head, followed by a low sweep, and Beckett was falling before she realized the first two techniques were only intended to draw her guard. Lightning quick, Castle struck as she fell, his right arm slipping easily around her left as she lost her balance. Pivoting, he turned her fall into a controlled take-down, snapping an arm bar into place as she hit the mat. Knowing he had her, Beckett quickly tapped out. Keeping hold of her wrist, Castle pulled her upright. His heart rate up, and the adrenaline flowing, he tugged a little too energetically, and she stumbled as she gained her feet, falling forwards. Instinctively, her hand came up to brace herself, slapping firmly into his well-muscled chest. His heart thrumming under her hand, she felt the movement of the muscles in his chest as he breathed deeply from the exertion. Frozen for an instant, they looked into each others eyes, feeling the slow pull as the distance closed between them. Both breathing hard, they were snapped out of their private moment by the sounds of Esposito and Ryan heading towards the change rooms.

Quickly, Castle slipped a baggy tee shirt on, and donned his sweat pants, not ready to face the inevitable questions from the other detectives just yet.

Beckett grinned at him, still pumped from the sparring, and their almost kiss. She was exhausted and sore in places she had forgotten she still had, but at the same time, her body vibrated with energy. Allowing her eyes to glide over her partners' form as he rapidly hid his physique from view, Beckett bit her lip and had to restrain herself from commenting.

The doors banged open, and in walked the other detectives, followed seconds later by none other than Tom Demming.

The newcomers look surprised to say the least at the sight of a sweating Beckett and the author.

"Hey, Castle!" Esposito quipped. "Beckett finally drag you down here to beat up on you, eh?"

"Something like that..." Castle replied. "She said something about needing to work off some stress, and figured I could hold the bag for her. I might even learn something one day, she tells me."

"So should we be worried, Writer Boy?" Ryan chipped in, a teasing grin on his face.

"Oh, I don't think you have much to worry about, guys." Demming interrupted, giving Castle a very pointed look. Beckett frowned as she saw her ex being unpleasant for no good reason. Tucking some loose hair behind her ear, she decided to have a little bit of fun.

"Oh, I don't know, Tom." An innocent look on her face, she started slipping off her gloves, and walked over to the trio. "He's a quick study, you might be surprised."

"Hah! You really think so, Kate? I think he doesn't want to damage his hands, myself." Demming took the bait, looking confident. "You think your star pupil is ready to learn a bit more?"

Castle looked at Kate, and back to Demming. Seeing the mischievous glint in Beckett's eyes, he decided to play along. "Well, it'd be a shame not to see if any of that stuff you taught me actually works..." He tried to look hesitant as he glanced at Beckett again and went on. "I'm assuming he's about as good as you are?"

"We're pretty evenly matched, if that's what you are after, Castle."

Esposito and Ryan looked at each other, then over to Castle and Demming, and back to Beckett. Grinning, they thought perhaps a little wager might be in order.

"Twenty says Castle lasts two minutes." Esposito offered. Rolling her eyes, Beckett replied.

"Since you boys seem so confident, how about dinner at Remy's? My shout if Castle taps out in under ten minutes. You buy for Castle and me if he lasts the distance..." A quick glance and the others jumped in.

"Deal."

"Ok Castle, looks like you are going to have to earn your dinner." Beckett gave him a saucy grin. Looking somewhat put out by the confidence Beckett was showing in her partner, Demming shook it off and made his way to the centre of the mats and took up a guard position. Cautiously, Castle met him there, fists raised, looking nervous. His watch at the ready, Esposito hit the start button, and signalled for the fight to commence.

Confidently, Demming threw a quick punch to his opponent's face. Castle left his block until the last possible moment, the fist just grazing his jaw. A little put out; Demming threw another couple of quick jabs, followed by a punishing uppercut to Castle's stomach. Seeing the punch coming, Castle hunched just as the blow connected, absorbing the hit and pulling back. To the others, it would look like he had just taken a very nasty hit. To him, he could barely feel it. The fight went on like that for some time: Demming trying harder and harder to hurt him, the blows just never seeming to connect, Castle always just stumbling, or flinching at just the wrong moment. Ryan and Esposito started off looking rather confident, but their faces slowly fell as it became apparent that Castle wasn't going to back down any time soon, and Demming had yet to land a telling hit. Peeking over Esposito's shoulder, Beckett saw that the allotted time had passed, and spoke up.

"Ok, Castle, stop playing with your food. We have work to do."

Demming faltered as the worried, confused look fell off Castle's face, to be replaced with a predatory grin. Ryan and Esposito looked at Beckett, startled, and then back to Castle, who had begun raining blows onto Demming.

Never quite fast enough with his defences, Demming pushed himself harder, but it was useless. Every move he made, Castle was there first, punching and kicking. Demming's face registered nothing but pure shock as Castle seemed to switch into another gear entirely. Two jabs caught Tom in the face, a ripping uppercut doubled him over and before the air finished rushing out of his lungs, Castle had pivoted into a perfect reverse roundhouse kick. Instead of connecting with Demming's jaw, Castle shifted his balance slightly, and slipped his heel in behind Demming's head, the momentum slamming his opponent face-first into the mat. A split second later, Castle had his knees firmly into the back of Demming's shoulders, and one arm in a joint-lock. Unable to focus, unsure what the hell had just happened, Demming tapped out.

Castle stood up, and used his grip on Demming's arm to help him upright. Grinning cheerfully, he clapped his dazed opponent on the shoulder as he helped him towards the bench, his voice dripping with false sincerity.

"Thanks for that Tom, I learnt a lot. Maybe we could do it again sometime?" Their own exercise totally forgotten, Ryan could do nothing but gape at the author, who didn't appear to even be winded. Esposito, however, ran his eyes over Castle, assessing. The Hispanic detective had learnt to fight like that years ago, back when he was in the military, and he sure as hell hadn't expected to see that level of combat experience from anybody else in the 12th precinct, let alone Castle of all people.

"Yo, Castle!" He spoke up, wanting to get in before they all headed out of the gym. "Where the hell did you learn those moves?"

"Just a little something I picked up in my reckless and stupid phase…" Downplaying the incident, Castle tried to shrug it off, but Esposito wasn't letting go that easily.

"You look like you've only just gotten warmed up man… feel like another couple of quick rounds? I think I can manage a bit more of a challenge than Demming…" Castle looked over to Kate, silently asking if they had the time to do this before they were all supposed to start work. She gave a small nod, wondering herself just who would come out on top.

"Ok, Esposito, I'm game if you are. Three two minute rounds?"

"Bring it on, Writer Boy!" He gave a chuckle as he dropped his gear bag next to the still dazed Demming and walked over to the centre of the mats. Castle glanced over to Esposito, and decided that he had better take this much more seriously than his drubbing of the hapless burglary detective. Quickly, he peeled off the concealing sweats and shirt, leaving only his gloves and bike shorts in place. Beckett forced herself to draw her eyes away from Castle's physique to watch the reactions of the other detectives. She was not disappointed, as both their faces went slack in astonishment, neither of them having suspected that the laid-back author was concealing such a chiselled body under his designer suits.

Castle casually walked over and faced off against Esposito, who now looked a lot less confident, his eyes doing another quick assessment, still trying to adjust to the new information.

"Ready?" Called Beckett, her finger on the stopwatch. "Go!"

They started off cautiously, each probing, testing, feeling for gaps in defences. The tempo picked up gradually, as they started to push harder and faster, trying to find a gap. Elbows and knees flew as they closed the distance. Castle over extended a punch just slightly, and Esposito latched onto his arm, slipping underneath and going for a reverse lock. Realising what was about to happen, Castle reacted, turning into the movement, spinning in place so that he was chest to chest with Esposito. Hooking his right leg behind , Castle shifted his weight forward, forcing Esposito backwards, tripping him. Keeping his forward momentum, Castle allowed himself to fall forward, bringing both his knees up, landing straddling his opponent's stomach, striking downwards as they fell.

They both paused for a second as Castle's open hand halted, just touching Esposito's throat. They both gave a small nod, acknowledging the point, and Castle stood, helping Esposito up. Shaping up again, they went at each other once more.

"Time!" Beckett yelled, halting the bout. They had not actually stopped between rounds, going a full six minutes, but the sparring partners knew it had only worked out that way because after each tap-out or acknowledged point, they had paused and reset.

Both were panting heavily, sweat running freely as they grinned at each other. Esposito extended his hand and grasped Castle's, before pulling him in for a brief man-hug.

"Bro, If I had known you do that, we'd have started doing this years ago! I can't remember how long it's been since I've been able to cut loose like that."

"Well, now the cat's out of the bag, I might just take you up on that. I haven't had to work that hard for a point in ages..."

"So, you gonna fess up where you learned to fight like that?" Castle flashed a cheeky grin, and replied.

"Would you believe research for a book...?" He raised his eyebrows, trying on his best innocent face.

"Not bloody likely!" Came the swift rejoinder.

"Then let's just call it an advantage of a misspent youth, shall we? I think we'd better hit the showers." He glanced over to a smirking and obviously impressed Beckett. "I think your boss is going to want you guys hard at work shortly, and the sooner I'm done, the sooner she gets her coffee..."

He grabbed his bag and headed for the showers, tossing a knowing smirk at the bench still occupied by Demming. As the door closed behind Castle, the others picked up their gear and followed Castle out. As they left the gym, Ryan turned to Beckett, saying,

"Ok, Beckett, what gives? Since when does Castle beat Esposito in a sparring match, and when the hell did you find out about him?"

"Ryan, that man has more layers than just about anybody else I know. I only found out yesterday, and couldn't resist the temptation of suckering you guys into betting on it. Speaking of which, does Thursday night work for you guys at Remy's?" Smirking, she left them at the door to their shower, and went to scrub down.