A/N: SPOILERS for 5x02! So, I was wondering why Beckett would show up at Castle's place with her weapon drawn and kicking in his door. This is what I came up with. Thanks to kimmiesjoy for proof-reading.

Disclaimer: I don't own anything.

Beckett was frantic, her heart rate spiking through the roof after running up the stairs in Castle's building because the elevator was under maintenance.

His text message came 15 minutes earlier. It didn't say much except for one thing. And it caused Beckett's stomach to churn with fear.

911.

Three terrifying little digits.

She didn't know what was going on – the only thing she knew was he needed her help.

He had left earlier today to go back home and change for his date.

Ugh. His date.

She had been more than aggravated about the fact that Castle had agreed to go out with Christina.

Christina. The entertainment reporter who shows up in her bikini to cover stories.

Who the hell does that?

But she did have to – begrudgingly – agree with Castle, it was kind of a brilliant move.

Esposito and Ryan had already become suspicious around them, to the point where they had looked at Castle more than a little incredulously when he had tried to get out of his date with Christina (after she, Kate, had thrown a fit) by using the precinct as an excuse. Ryan had even asked him since when he let cop work get in the way of his busy social life.

Lanie on the other hand was grilling her about the 'new guy' she was apparently having sex with and it was only a matter of time until they would all put two and two together.

No, if they wanted to keep their relationship a secret, going out on a date with Christina was the perfect opportunity to throw them off their trail. So she had agreed.

That didn't mean she had to like it.

At all.

So when Castle had left the precinct she was more than a little off her game. Concentrating on going through financials had been hard.

And then, one hour later, she got his text. 911.

Castle wasn't on his date yet, they were supposed to go out at 8pm and it was barely 7. So he still had to be at the loft.

And that's where she was heading now – full of panic and more than afraid at what to expect. All sorts of worst case scenarios were flashing through her mind - images of Castle tied up, with a gun to his head, or lying shot on the ground in his own blood, unable to move. This definitely didn't help her to stay calm. Unfortunately the boys were out following up a lead when the text came, so she had called Espo telling him to meet her at the loft as soon as possible.

She reached the door to his loft and listened carefully, but couldn't hear anything. She was just about to knock when she heard a commotion coming from the other side, followed by a dull thud. Without even thinking about it she drew her weapon and kicked the door in, ready to shoot anyone who was about to hurt Castle.

But what she saw, left her frozen in place. Unable to comprehend the sight in front of her she stood completely still, mouth open, heart plummeting into her stomach.

There on the couch was Christina - in her bikini - straddling Castle and apparently just coming up from a passionate kiss, judging from the lipstick all over Castle's face.

"Castle?"

"I know who the killer is," he told her breathlessly while slightly turning to her.

She was rooted to the spot.

Didn't know what to do.

Every single fear she had been harboring about his commitment to this relationship, every single insecurity she had concerning his playboy days came rushing back to her.

Of course, rationally she knew they had agreed for him to go on this fake date. Rationally she knew he had sent her a text to let her know he needed help. But the image of them both on her couch was just too much for her. So she lashed out.

"What the hell is going on here?"

He must have heard the anger and the deep hurt in her voice because he shoved Christina away immediately and didn't try to make a joke. Christina looked more than a little flustered at the interruption of her date. He excused himself, stood up from the couch while whiping the lipstick off his face and headed towards Kate, stirring her away from Christina, trying to apologize and launching instantly into the details of their case.

She was so stunned and dazed by what had just occurred that she didn't put up much of a fight, letting him lead her away to his study, completely ignoring Christina.

"I'm so sorry Kate. She showed up here early, ripped her dress off and kinda threw herself at me like I was the last guy on the planet. God, I…"

"So what…she overpowered you? And you were too weak to do anything about it? Is that it? Why didn't you put her in her place? Why the hell didn't you tell her that you were…," she trailed off, visibly deflating before his eyes, all the anger leaving her, shoulders slumping down in defeat.

Of course, he couldn't tell Christina he was in a relationship with his 'muse' after declaring on TV he was single, for the whole world to hear. To an entertainment reporter no less. She would never keep quiet about that.

"Kate, I would never…look, after she stripped down to her bikini and made perfectly clear where she wanted this to go, I tried to distract her, offered her a drink and made her talk about the case a bit. While I was in the kitchen mixing the drink, I texted you. I figured you would come here and save me from her. I wanted to tell you to think of an excuse to cut the evening short, something like a lead in the case…but…then she followed me to the kitchen, and I had barely enough time to send you the 911 call. God Kate, I really am sorry, but I couldn't tell her to back off, not if I didn't want to blow our cover."

Kate was at a loss for words. He looked genuinely contrite.

She sighed. It was ridiculous.

She was the one who had made it perfectly clear the other day that they should act in public as if they were single. And the fake date was a ruse designed to throw everyone off their trail. So she couldn't possibly be angry with him.

She let her head fall to his shoulder.

"I know. God, I know Castle. And I hate it."

His arms came around her, holding her to him while kissing the top of her head.

"You're jealous," he stated matter of fact but with a little awe and glee mixed into it.

He sounded far too smug for her liking and she pushed him away a bit, narrowing her eyes and fixing him with her best death glare.

"If you think this is funny…"

"Nope, not funny at all Beckett…just hot."

"What?"

"God, you should have seen yourself - kicking down my front door, barging in hell-bent, your weapon drawn, ready to get your man," he was brimming with excitement and pride. In her.

She had to admit it was kind of endearing. And hot. Not that she would tell him that.

Suppressing a smile she raised an eyebrow and fixed him with a look.

"My man, huh? Well Castle, then be a man, go out there and get rid of Ms Bikini – for good. We have a murder to solve. Didn't you say you know who the killer is?"

With that she headed to the door of his study, before suddenly spinning around and striding right back towards Castle. She pressed her mouth against his, kissing him hard and aggressive - marking her territory. She let her hand trail down his back and lower, squeezing, while pressing her hips suggestively to his front.

"And if you're right about the killer, well, maybe you can prove to me later tonight how much of a man you are," she informed him, before turning around and leaving him dazed and more than a little turned on in his study.