AN: Hello all! How amazing was episode 6, huh? Here's just a little expansion piece on the final scene of last night's episode. I can't wait to read all the fanfic that scene is going to inspire in you guys throughout the course of the next week. Enjoy! P.S. I don't own Castle, the dialogue, or the song used in this story. Bummer.

She wasn't thinking. She wasn't feeling. She was just...running.

With her gun in hand, Kate sprinted toward the stairs that led up to the apartment. After kicking the door open, she called his name. Her voice broke, filled with panic and uncertainty.

"Castle!"

There he was, tied to a chair, with a similar look of fear in his eyes. She breathed a sigh of relief and bent down to his level to untie his hands.

"I'm so glad that you're okay", she said in his ear.

In this very rare and vulnerable moment in her life, Kate Beckett had allowed herself to panic. The regularly calm and collected detective had broken down and given in. The fact of the matter was that she couldn't lose him. She depended on him to get her through the day. In those moments of uncertainty of her partner's fate, she realized that she would never be able to live without him.

Kate was rattled and shaken to her core at these revelations, but managed to calm herself down once Castle was free and safe.

After he had been examined by an EMT, Kate found him sitting by the pool of the apartment complex, staring blankly into space. She quietly walked over to the bench and sat down, offering him a cup of coffee. He thanked her, still looking off into the distance.

After a few minutes, she broke the silence.

"Tell me something Castle, why did he let you live?" Truthfully, she wasn't asking him. She was also asking herself. Why would a serial killer let the last man to see him live? She just didn't understand.

After hesitating for a moment, he responded, "To punish me. Make me pay for ruining his plan. Now he's gonna kill again, all because I couldn't stop him. And I feel so…" he trailed off, at a loss for words.

When Kate looked at him, she could see the hurt and frustration in his eyes. She knew that hurt. She knew that frustration. Instinctively, she reached over and placed a hand on his knee, showing him that she was there. She understood and more importantly, she cared.

"I know the feeling," she said gently, looking off at the reflections on the concrete, made by the water in the pool.

He looked at her. He blamed himself for letting a killer get away. She blamed herself for letting her mother's killer get away. Castle then realized that they were bonded. There was nothing that separated them, and nothing ever would. Despite other relationships he may have, Kate Beckett had his heart, solely. She would always be 'the one.' His one.

"I know you do," he responded, as he placed his large hand around of her small, thin one. His thumb rubbed against hers gently, and her warmth pulsated through his hand.

And they sat this way for a long time, not thinking, not feeling. Just…being.

Gentle you were in your first presence,
hazel to brown eyes embraced innocence.
We dressed each other in colors of intrigue,
first words to each other sang comfort's melody.
Childlike was your first gracious allurement,
her offering hands touched mine in content.

-"Holding Hands", Downset