Disclaimer: The wording is mine but the characters aren't

Thanks for the reviews. Here's another chapter to keep my English from deserting me completely here, in the land of the rising sun.

Are you following?

"We spent the night at my place," he explained. "Beckett, all my windows are double-glazed. You can't see inside."

Her stomach dropped as she caught his meaning, her face turning as grim as his. "She was there for the other two when we were coming from my place." Kate finished the reasoning. This woman had known about the crime scenes, because she had been watching Beckett's apartment and had followed them.

It was like dejavu.

"She's been watching us."

..

3.

Neither had the stomach for kebabs and barely picked at the pizzas Castle had delivered. For the first time there was a whole pizza left over to fit into the break room refrigerator without the excuse of a sudden call or break to tear them away from their meal.

They spent an unproductive hour going through the motions, opening and closing files, typing information into the database, all the while waiting for the chime of Ryan's phone. Gates stood restlessly and made her way to the window or the door frame an inordinate number of times. She had given permission to identify the mystery woman as she pertained to their homicide cases. The Captain's concern was thinly veiled as was her relief at having a legitimate reason to allow the team to pursue it. By the book.

Castle recalled the strange, questioning look she had fixed on him when they had updated her; clearly trying to ascertain his opinion. From the frown lines, he could only assume that she was thinking the same things he was: that this probably wasn't the work of a Nikki Heat fan.

He liked to think she would have allowed them the time and resources if she thought it was, but he wouldn't put any money on it. This was her protecting one of her own: a status he wasn't sure she had allowed him yet.

"Just got an email. I'm forwarding it," Ryan announced. The change in atmosphere was instantaneous, drawing Caste out of his slight slouch and pulling Kate's chin out of the hand she had propped on her desk.

"Louise Prenton," Ryan read off while Beckett opened the mail and attachment. Tech hadn't just gotten a name; there was a copy of Louise's DMV.

"Running her now," Esposito said tersely. Castle opened up a new text message box and began entering the information to send to Black Pawn.

"What do we know about her?" she asked.

"Not much," Esposito replied, his eyes rapidly scanning the document he pulled up. The printer kicked into life on the other side of the bullpen and Ryan was there before the last page was finished. "33. Lives in TriBeca."

"Job?"

"Not listed."

"Priors?" Castle looked up from his message.

"None," Ryan answered for his partner. "She's clean."

"And you're sure she's the right one?"

"Tech confirmed the facial features with all three photos and our sketch. It's a match for the DMV photo. Tech says Officers Saunders and Keene positively identified her."
Kate looked up and saw Gates in the doorway. The older woman gave a curt nod and all four reached for their jackets, their faces set and their weapons sliding comfortingly into their holsters.

"How long will it take Black Pawn to get back to us with the results?" Beckett kept her focus intent on the road, practically glaring at the asphalt and slow moving cars in front of her.

"Not long. Gina said she would have the records waiting."
She glanced over at him, her eyebrows furrowed but he was at a loss to the reason behind it, or rather, he could think of too many reasons. Ex-wife, the knowledge the records weren't going to be of much use, the fact he didn't say anything to comfort her. Maybe that she didn't have the information in hand already.

Unable to decide, he kept with silence and after a few seconds she retrained her focus on the drive. He wanted to say something, but this tense side of her always affected him, winding his muscles tighter with tension until he just sat in the passenger seat and kept his teeth clenched, trying not to implode from the pressure.

Being the focus of observation was not new to him, but he had never been one to enjoy it outside the determined public events. It was with a previously impossible fervor he wished that this time this is what it would turn out to be: some obsessed fan he could sweet talk in to leaving them alone or file a restraining order against.

Damn his gut. And the Captain for her suspicions.

He can't have set another madman after Katherine Beckett.

The closer they got to the apartment building the heavier his stomach got.

"She lives pretty close." He cleared his throat as he let the thought out.
"Castle," she shook her head tightly.
"You were thinking it, I was just saying it."
"Well don't."

He didn't bother with a retort. At the moment she wasn't Kate, she was Detective Beckett and she was completely focused on a threat. He considered it a moment before realizing that he was incorrect.

At this moment she was purely Kate.

Worried and fiercely protective. Of him.

They left Ryan and Esposito in the small lobby then took the stairs up to the third floor. Despite the un-stalker-ish feel of the surroundings, Castle felt his stomach roll when they found the door. He wondered idly how much more it would take for his stomach rebel completely; or give him an ulcer.

"NYPD," Kate called, the side of her fist connecting solidly with the door.

His foot twitched restlessly at the anticipation, unsure if he wanted to hear the sound of a bolt being slid back or not. Denial could be a happy place. He looked over at his companion and saw she had internalized whatever she was feeling, leaving her face remote. He didn't miss the way one of her hands was under her long jacket though, removing any obstacles or hesitation from a smooth draw.

The corridor was well lit as they stood silently outside 306. It didn't do anything to aid the ache of trepidation and the wish that Ryan and Esposito weren't waiting at the entrance. He looked to the brown laminated door, confirming it was still silent and closed, the way it had been two seconds ago. In a habit he had picked up after running with Powell and a few other acquaintances, he dropped his eyes to the lock.

"Kate," he murmured, stepping in front of her for a better look. She followed his eyes. "This lock is new."

He took in the bronze fitting. It was much more worn than the lock itself. The metal of the locking mechanism itself was pristine and he had to assume it was the work of a fairly good locksmith. But there were no other little scratches on the metal: no one had fumbled with a key in a hurry to get out of the cold, or with unsteady, drunk hands. The lock was unmarred and subtly lighter than the rest of the fitting.

She took one look between him and the door before she dropped her hand from the holster and reached for her phone.

"Yeah Esposito. Hey, can you see if you can get a hold of the manager? I want to know how long Prenton has been living here. Ryan can interview the doorman and keep watch."

Driving past her own apartment a mere two minutes before she pulled up here must have started her thinking, but he couldn't regret her move towards the possibility this might not have anything to do with him at all. If it would make her more careful, he didn't care. Just as long as she stayed safe and no one tried to blow up her apartment.

She snapped the phone closed and repeated her demand on the door. "Detective Beckett, NYPD. Open this door."

His eyes clamped closed. She announced her name – to a possibly unhinged stalker.

The vibration of his phone saved her from a reprimand when he opened Gina's message.

We can't find any record of a Louise Prenton, Rick. In your mail or anyone else's. We haven't had too many odd ones lately but you can take them in if you need to.

"Gina?"

He nodded. He had anticipated the answer, but upon receiving it was aware just how unprepared he was to have it confirmed.

"Nothing?" she surmised.

He shook his head, his face stiff with keeping it under control.

The door swung inwards, startling both of them, Kate's hand diving back into her jacket. When they saw who had opened the door however, their movements hitched.

"Detective Beckett," the voice was warm and delighted and came from a smile that was decidedly crooked. It didn't look roguish or playful on this man's face; it looked distinctly unnatural. Just like the sandy brown hair which was overly styled and screaming bottle-born.

The anxiety he felt earlier sky rocketed as he took in the other man's careful appearance. It had to be a joke.

Beckett recovered before he could. "NYPD," she identified herself again. "We're looking for Miss Louise Prenton."

"She's not here, Kate," the man answered, gesturing for her to step in. The movement was restrained by the dress shirt and jacket he was wearing. Castle felt a little nauseous at the way his own outfit of two days ago had been recreated on this man. Just like the hair color, the hair cut, even the smile.

At least he would never have to wear that shirt again. Kate had ripped it off him.

Beckett didn't flinch at the use of her given name. "Who are you?"

"I'm her partner," he flashed that unnatural smile again. "She doesn't really like the term 'boyfriend'."
"And what is your name?"

"How rude of me," he took Beckett's hand and cradled it between his own. "Thomas Donovan," he tried to bring the hand to his lips but she firmly pulled it away. He didn't acknowledge this rejection verbally; instead his eyes gleamed a little more.

"Mr. Donovan," her hand tensed into a claw at her side. "Do you know when Ms. Prenton will be back?"

"I'm afraid she didn't quite mention," he smiled pleasantly.

"Did she tell you where she was going?"

"What can I say? She's a free spirit. I'm sure you understand."

"How long have the two of you been together?" Castle asked, entering their conversation for the first time and holding up the picture frame from the coffee table.

"A month."

"Must be going well," Castle gave him a knowing smile, trying not to shoot Beckett a look at the appearance of the time period that would activate Thomas' firewall. "She gave you a key and leaves you alone in her place after only a month."
He spread his hands depreciatingly. "What can I say?" he repeated but his attention was solely on Beckett.

"Oh, so many things," Castle never let the polite smile slip. But he could feel his gums protesting the force of his teeth rebelling against each other.

"May I ask what this is about?" Thomas asked Beckett.

"We just had a few questions to ask her," Beckett was still in control of her poker face.

"I'm sure she'll be sorry to have missed you," he didn't sound sorry on his girlfriend's behalf, but more admiring.

Castle fought off a shudder on Kate's behalf.

"Before we go," he addressed Thomas. "Do you mind if I borrow your bathroom?" He was loathe to leave Kate alone with his doppelganger, but she could take care of herself and they really needed to have a look around. They couldn't have come this far just to have a five minute conversation.

From the reluctant look she shot him, she was less than thrilled at being left alone as well. Her host was exultant however and merely waved towards the back of the apartment, already moving closer to Beckett.

"I'll be back in a minute," Castle assured her, brushing her shoulder lightly with his on the way past: the most he could do in company. She leaned into the brief contact and her eyes tracked him until he was in the short hallway.

When he was sure he was out of sight, he pulled out his phone and opened a text message to Ryan while he poked his nose in to the bathroom. There was nothing obvious out of place so he crossed to the partially closed door opposite. Maybe this is where Thomas had been coming from when he opened the door.

It was the bedroom.

The bed took over a large proportion of the space and he saw a camera on a low dresser. There was a laptop with the screen saver activated open on the comforter. A quick glance at the customized screen saver photos fading in and out had his stomach acid churning. It was pictures of them- he and Kate. He ran his finger over the mouse pad and was confronted with another picture of them.

It was from last night. The wooden blinds over Kate's windows obscured a good deal, but there was no mistaking at which point in the evening it had been taken. Kate was straddling his lap, both of their pants not in the picture. Neither was her shirt. Thankfully he knew the removal of the rest of their clothing had not taken place until they had moved to the bathroom, but was aware that there was more than one time in the last month where they had taken full advantage of the open planning of her apartment.

It looked like they weren't the only ones. Unconsciously recalling the flush on Thomas's cheeks when he opened the door, Castle could only guess Mr. Donovan liked it very much. Enough that he wasn't able to open the door the first time.

He tasted bile in his throat, creeping up on the back of his tongue and he dry heaved, struggling for control.

Not sure if he had the control to talk, he started on the text he had neglected when he entered the room.

Ryan, get Esposito and get up here.

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