A/N: Hello everyone in Castle-world! I'm Katherine, and I normally write Harry Potter fanfiction, and I used to dabble in Grey's Anatomy and Private Practice. However, I have recently become obsessed with this show and Caskett. How could I not? Anyway, this is my first Caskett fanfiction, so I hope you'll be nice to me and maybe review.

Disclaimer: This delicious pairing isn't mine, but how I wish I had a Stana for my own.

Chapter One: Siren

Kate Beckett never realized how loud the sirens on police cars and ambulances were until she was riding in one. She lied back in the gurney, her eyes closed against the pain in her chest that radiated throughout her entire body. She had been grazed by a bullet before, in the left arm, but she had never actually been shot. She suddenly envied everyone she had ever shot. Tears streamed from her closed eyelids as the ambulance stopped at a red light.

Her heart started hurting more, and she gasped for air. She wrenched open her eyes, looking for something to hold onto, but saw nothing but the EMT that she didn't recognize and the wires tangling everywhere. Grey spots started forming around the edges of her vision. The EMT glanced quickly at the monitor that kept track of her heartbeat. It was speeding up. Her blood pressure was dropping.

"Get a move on, we're losing her!" he shouted to the driver. The man's face blurred into a mixture of colors as she faded into darkness.

Richard Castle prided himself on how he kept his cool. He was always…cool, calm, collected. Some people, like his daughter or his mother, might disagree, but that was because they had seen him at his worst. They didn't count right now. As he put one foot in front of the other faster than he had ever done before, Castle couldn't help but feel his 'cool' slipping away.

He almost slipped on the slick hospital floor, and he wrinkled his nose at the sterile smell of nurses and doctors. He took a turn too sharply and had to leap aside to dodge a gurney carrying a body bag. He gasped inwardly and shuddered, trying not to think of the possibility that Beckett was in that bag.

Finally, he found a nondescript waiting room with people he recognized. Everyone was a few shades paler than usual, and no one was speaking. Castle tried to keep his mind away from the possibility that they would only look this grave if…

"Where is she?" he asked, anguished. Ryan and Esposito looked up from where they were sitting, heads in hands, looking frightened. Captain Montgomery didn't even jump.

"She's going to be fine," he said in his soothing voice. He put a hand on Castle's shoulder, trying to steer him to a chair. Castle threw off his hand and started pacing.

"I need to see her," he said, running his hands through his hair for the hundredth time. "This is my fault, I have to see her!" He took a wild look around. "Where is she? Which room is she in?" Ryan and Esposito looked at him like he was a crazy man, with hints of pity on their normally smiling faces. They both knew the silent pain he was endearing, hoping that he would have a chance to see Kate again, that she was still alive, so he could tell her…he couldn't even wrap his mind around the thought.

An official looking man in a lab coat had joined them now. "Excuse me, are you here to see Katherine Beckett?"

"YES!" Castle practically shouted. Everyone turned to glare. Ryan even let out one grim chuckle at the awkward situation. Esposito elbowed him. The doctor didn't look amused, but flipped to a page on the chart in his hand and consulted his notes.

"Which one of you is Richard Castle?" the doctor asked.

"The apoplectic one," Montgomery muttered, resuming his seat. "I assume she's going to be okay?"

The doctor nodded. "She'll be fine, she just got out of surgery. She was extremely lucky." The entire group exhaled as one. Ryan wiped his eyes. Castle unclenched his jaw and fist. "Mr. Castle, she asked to speak to you first."

"Typical," Esposito muttered, his personality restored. "Give her a kiss for us!" he called to Castle's retreating back. Castle stumbled after the man in the coat, wondering what exactly he would say when he saw her. He wondered if he could hug her, or if she would be in too much pain. He wondered if she would be half-asleep and delirious from the drugs. He wondered so many things he didn't even remember how his feet carried him to that door.

She was attached to so many wires. Her beautiful face had the smallest traces of makeup on it, and she looked pale and terrified. But she hid it behind her usual bravado. She smiled at him when he came in, and she didn't look mad at all. She looked…grateful.

"First of all, I just want to say—" Castle began.

"Shut up, Rick."

He stopped short. "You…you called me Rick."

She nodded with a smirk. "I know. I wanted to get your attention."

He continued to stare, so she continued. "This was not your fault. If it hadn't been for you, we never would have found the killer. And we never would have caught him. And…and I find this the most important: I would be dead." Tears shone in her eyes at her last sentence, but she held them.

"Beckett, I—"

"If the next thing out of your mouth is going to be some sort of apology, I don't want to hear it." Suddenly, the strict Beckett was back, and Castle snapped his jaw closed. She fluttered her lashes at his silence and his neck got warm, and he knew his face was turning red. Beckett caused too many flushed cheeks.

"Okay, fine," he said. He sat gingerly on the side of her hospital bed, and she gently placed her hand on his knee. He grasped it tightly and held on like he would drift away.

She waited, but he never spoke. "What?" she asked, smiling sweetly. In a hospital bed, without her heels and blazer, she looked so much more tender and soft. He was itching just to touch her skin.

"Kate, you are—"

"Babe, are you okay?" a deep voice, scratchy and frantic, interrupted him. Castle closed his eyes and prayed for patience. The black leather jacket, the black hair, blue eyes filled the room with tension. Castle stared into Beckett's gorgeous eyes for a few seconds, waiting for her to speak. But what did he want her to say? He didn't even know what he wanted right now. When she didn't speak, he nodded and took his leave, without bothering to say goodbye.

Beckett watched him go as Josh gave her a kiss. Her heart ached in a way she couldn't quite place.

"What happened to you? Why didn't you call me? Did Castle have something to do with this?" he rattled off question after question, and soon, Beckett just tuned him out.

"Babe?"

"Sorry," she lied, "the meds are kicking in." He took hold of her hand and kissed her forehead.

"Why don't you tell me what happened?" he asked.

Beckett glanced again at the doorway, and then turned her eyes on her boyfriend. "I guess I could do that," she said, and prepared to embark on the tale.