A/N: Thank you all so much for all the story alerts, favourites, reviews etc. Then encourage me to write. At first I wanted to just write five chapters to this story. But, as you will read, is not going to work anymore. I don't know for sure, but I'm going to add at least one more chapter to this, maybe more. Let me know if you liked it!

Big Mistake

When their lips touched, it was like all the built up tension from the past months came together in that one kiss. Although they were a bit hesitant at first, soon they parted their lips and started exploring each other's mouths with their tongues as the kiss grew more passionate. His hands rested on her waist and he carefully pulled her closer to him, increasing the contact between their bodies.

There was a voice in her head yelling at her that she should push him away, that she shouldn't be doing this. She was kissing Richard Castle. Richard Castle, author and pain-in-the-ass extraordinaire. Yes, a small part of her was telling her this was wrong. But why, why, did it feel so right? His lips, his tongue, every touch, it all felt so good. So she shut out the voice in her head and she just did what her body told her to do. Her hands trailed over his chest, encircled his neck and found their place in his hair, not allowing him to stop.

Kate Beckett never failed to surprise him, but this was… well, definitely a pleasant surprise. Of course he had imagined what it would be like to kiss her, to touch her and have her close to him, for Nikki Heat. At least that's what he told himself, but Nikki Heat had become an excuse to be with her. Not the other way around. When he felt her hands tangle up in his hair and she trailed his lips with her tongue, he couldn't hold back a soft low growl. She was so much better than Nikki Heat.

Castle slowly walked forward and they slowly moved, not breaking the kiss. When Kate felt the cool brick wall against her back, the little nagging voice in the back of her head started to come back again. She tried to ignore it though, she didn't want to think. All she wanted was him, and her whole body was aching for some skin contact. Unfortunately, the voice was now yelling and she couldn't ignore it anymore. Castle. Why was she kissing him? Sure, he was a great kisser, better than great actually, but why? He had just done something she'd clearly told him not to. Plus he had shown up at her apartment and entered uninvited. And of course there was his ridiculous phone call.

Suddenly a thought hit her like a thunderbolt. Nikki Heat. He had been writing a scene for Nikki Heat. Was he doing 'research' now? Was this all for Nikki Heat? Damn, she should hit him for kissing her. Oh wait, she had kissed him. He kissed back, but she had taken the initiative. Shit.

Finally she broke off the kiss and they both gasped for air. Kate felt his hands on her waist, it felt like the touch of his fingers burned straight through her clothes. Also his body was so close to her, she could feel the heat of body radiate against hers. Her heart pounded loudly in her chest and she could hear the loud, unsteady breathing of them both.

Okay, she thought, we need to regroup here. She placed a hand on his chest and tried to ignore how firm it felt under her hand, also she thought she felt his heartbeat, but it could just as well be hers. She gathered all her strength and pushed him away and said, her voice sounding more unsteady than she liked, "Castle, you should go."

"Wh− What?" He breathed.

"You should go." She repeated, her voice a bit more stable than before.

A look of utter confusion spread across his face , "Why?"

"It's late" She simply stated. He was still standing close enough to her to make her feel uncomfortable, so she walked over to the door and opened it.

"That doesn't answer my question." Castle commented. When she didn't reply he continued, "Look, if this is about reading that notebook, I already told you I'm sorry. I know I shouldn't have done that, and if I would've known… Well, I'm just really sorry. But please, don't just make me leave because of that."

"Who says it's because of that, that I want you to leave?" She said. Her voice made it sound harsher then she'd intended and she saw a mixture of hurt, confusion and worry in his eyes. Damn, he had to leave soon otherwise she wouldn't be able to let him go. She wanted him but she was too scared. Maybe it was all for Nikki Heat. Or maybe she would just be one of his conquests.

Even if he did have feelings for her, she didn't want to lose him. Ever since her mother's death, she wasn't good at keeping long-term relationships work. So if they got together, they would probably break up as well. And she didn't want that. So it would just be better if they just stayed partners, maybe even friends. She had decided.

"Castle." She said and gestured towards the door.

"Kate..." He said with a sigh. "Don't do this."

She narrowed her eyes before she stepped around him and pushed him out of the door. He was too surprised to struggle. "I'll see you tomorrow at work. Goodnight Castle." She said and she shut the door behind him, just before he could get back in again.

Kate had hoped that she would feel some sense of euphoria. But all she did was feel empty. She leaned against the still closed door and sagged to the floor. She gently touched her lips, that were still burning from their kiss.

A loud knock on her door startled her a bit but she ignored it. After what seemed ages, the knocking stopped and her apartment was silent again. A few minutes later her cell phone rang. She didn't pick up. She felt like she had just made the biggest mistake in her life.