Author's Notes: I really, really had no intention of writing (let alone posting) this – it seemed so overdone – but the funny thing about plot bunnies is that they like to have babies. So when this idea popped into my head, what was a poor writer to do but write it? Anyways, I tried my best to keep them completely in character on this one. I may continue it; not sure yet. Anyway, enjoy!

Beckett hung up the phone and picked up her purse, ready to head to midtown to search the victim's apartment. Castle, usually close on her heels, was sitting in the chair next to her desk, staring blankly into space.

"You okay, Castle?" she asked, looking back to see if he was following her yet.

"Hm? Oh, yeah," he said, standing up slowly.

She might have imagined it, but he seemed to be moving stiffly, and she thought she saw him clutch his stomach for a second. Brushing it off, she headed out, thinking of things she wanted to look for once they got to the vic's house. Halfway to midtown, though, her plan was interrupted when Castle suddenly demanded that Beckett stop the car.

"Are you serious right now?" Beckett asked, incredulous. "For what?"

"Just stop the car," he repeated. "Right here."

Beckett sighed impatiently, but did as he said, hoping an explanation was forthcoming. There was. He had hardly opened the door and climbed out when he started vomiting. The light went on in Beckett's mind, and she rolled her eyes at him.

"Castle, you really should quit binge drinking on weekdays," she said. "Most people consider that unhealthy."

"I didn't touch a drop last night," he said before heaving again. "I think I'm dying," he added.

"Oh, man up, Castle," said Beckett condescendingly. She thought back to when he had been bitten by the man with porphyria and become convinced that he was doomed to become a vampire. Surely this was no different. "Shake it off and let's go. Or would you like me to call your mother?"

"Beckett, this isn't funny!" Castle insisted.

Beckett noticed how white his knuckles were as he held her side mirror in a death grip. "From where I'm sitting, it's pretty funny, but it won't be when I shoot you for breaking off my mirror."

"Kate, I'm serious!" Castle snapped.

There was a tone in his voice, wholly unlike his usual mischievous self, which made Beckett reconsider, and she reluctantly got out of the car to see what he was so distressed about. When she circled around to where he was standing, she drew in a sharp intake of breath at what she saw, and her own stomach turned slightly. "Castle, that's a lot of blood," she breathed.

"Uh huh," said Castle, holding even tighter to the mirror.

"What happened?" Beckett asked, trying to remember if Castle had ever mentioned anything, a bleeding ulcer perhaps...

"I'm not sure, but..." he let go of the mirror and pulled up his shirt, revealing a cluster of nasty bruises on his abdomen.

"Oh God," said Beckett, remembering the scuffle from the day before. They had been in the process of arresting a suspect, and Castle had ultimately caught him, but not before taking a few punches. "How long has this been going on?"

"The bruises, or...?"

Beckett nodded towards the bloodstains on the sidewalk.

"Just now," said Castle. "I've had a stomachache all day, but I thought it was just something I ate... I guess not."

The adrenaline had kicked in, and Beckett decided it was time for action. "Come on," she said. "I'm taking you to the hospital."

This had the effect of scaring Castle even more. "What? You're serious?"

"Shut up and get in the car!" said Beckett, already restarting the engine.

Castle was quite uncharacteristically quiet on the way to the hospital, and for most of the ride he was doubled over as if in pain – which, Beckett reasoned, he probably was. She eyed him nervously whenever they stopped at a traffic light, and tried not to think about how much blood there had been. It wasn't that the sight of blood bothered her. She was a homicide detective for crying out loud. It just upset her when so much of it was spilled on the ground by someone she... someone she cared about.

"Beckett?" Castle said quietly, a few blocks from the hospital.

She was about to ask him what, but the color of his face answered her question, and she pulled over, flinching slightly when Castle got sick again. "Are you okay?" she asked. He didn't answer, and Beckett unbuckled her seatbelt and crawled across the console, putting a hand on his back. She frowned, looking at the blood that was smeared across the back of his hand when he wiped his mouth, and the puddle of it dripping down the gutter and into the storm drain. Beckett found him a couple of paper napkins, then restarted the car and stared stone-faced though the windshield. "We're almost there," she said.

Once they arrived at the hospital, Beckett checked them in at the front desk of the emergency room, then excused herself to call Montgomery once Castle had assured her that he would be fine alone for a couple of minutes. She explained the situation to the captain, and he agreed to send Ryan and Esposito to take over for her. That handled, she went back to the waiting room.

"Do you want me to call your mother, or Alexis?" she asked.

Castle shook his head. "They're in Chicago looking at colleges. It'd take them hours to get here even if they got on the first plane out, and I'd rather they didn't worry at all."

Beckett frowned, jumping ahead to the worst-case scenario. One of her nightmares was having to tell Alexis that her father wasn't coming home, and she hoped she would never have to have that conversation. But she understood his reasoning, and hoped everything would be fine, and she could tell Alexis instead that it had really been no big deal.

Over the next couple hours, they went through the whole gamut of this test and that, and finally came to the conclusion that he was bleeding enough to warrant surgery. Before Beckett could gather her wits, he was being wheeled off and she was left quite alone in the hallway. She wasn't sure why she was there instead of in an actual waiting room, but it was just as well; she didn't feel like being surrounded by strangers. At one point she realized it had been several hours since she had used the bathroom, and set off to find one. Safely locked behind a stall door, she covered her face with her hands and breathed deeply, willing tears not to fall. He'll be fine, she told herself. The harder part to reconcile was why she cared so much. It crossed her mind for a second that she could call Josh – he was a doctor, after all, and might have some words of reassurance. Yet it seemed terribly perverse to call Josh to talk about Castle, and the convolutedness of it all made her head spin.

Having mostly regained her composure, she returned to the awkward hallway chair and waited. She had absolutely nothing to do. The only thing she had with her was her purse, which at its most exciting contained her police notebook, her cellphone, and her backup pistol. She tried to keep her mind occupied with the details of the case they were working on, but everything seemed to remind her of some other moment with Castle, which brought her back to the very real danger he was in, and how much she would miss having him around the precinct. She would never admit it, but she dreaded the day he decided, for whatever reason, to leave. She had very intentionally avoided thinking about this, and convinced herself foolishly that it simply wouldn't happen. She held her phone in her hand, circling her thumb around the keys mindlessly, almost as if she expected him to call her when he was out of surgery. That was ridiculous. She took another breath to calm herself, wishing she had someone to talk to. She would have wanted to talk to him, but that was impossible; he was the reason she needed to talk at all.

Of course, she thought suddenly, sliding her phone open and dialing Lanie. She couldn't believe she hadn't thought of it before.

"Hi, Beckett, what can I do for you?" Lanie's warm voice answered after several rings.

"Hi Lanie. Can we talk for a minute?"

"I was about to start an autopsy, but if you need me to check something, or—"

"Can it wait?" Beckett cut her off.

"Okay, what's going on? You sound awfully upset, what happened?"

Beckett hesitated. "It's Castle," she said.

"What about him?" Lanie asked. "He working your last nerve again? Girl, I know he can be a handful, but you need to loosen up once in a while!"

To her great frustration, Beckett found herself on the verge of tears again. "No. I'm at the hospital with him. He's in surgery."

"Surgery?" Lanie repeated. "What the hell happened?"

Beckett explained how Castle had suddenly started vomiting blood, and how she suspected it had started when he had taken punches from the suspect they were arresting. Lanie listened patiently.

"So?" Beckett asked. "What do you think?"

"It's hard to say without taking a look at him myself," said Lanie. "You definitely did the right thing taking him to the hospital."

"Yeah," said Beckett. She had known that much. "You think he'll be okay?"

"Modern medicine can pull some amazing stunts," said Lanie. "Don't worry too much, sweetie. But at least if you have a panic attack, you're already in the hospital."

Beckett couldn't help but smile a little. She knew Lanie's comment was only half sarcastic. "Thanks, Lanie," she said.

"Anytime. You know I got your back. You let me know how things go, okay? I'm glad you called."

"Okay. Yeah. I will."

Beckett slid her phone shut, and returned to staring at the pastel floral painting across the hall. She was pretty sure she would be able to accurately describe every detail of the painting to their sketch artist if she were asked. Quite some time later, a male nurse wearing lavender scrubs approached her from the end of the hallway. "Miss Beckett?" he asked.

Beckett looked up, nodding acknowledgement of her name.

"He's coming out of surgery now. The anesthesia will take a while longer to wear off, but he's going to be fine. You can come see him now."

Beckett sighed a long breath of relief, running her hand through her hair and leaning back into the chair. "Thank you," she said. "Which way is it?"

"Follow me," said the nurse.

In the recovery room, Beckett found a much more comfortable chair, or perhaps it just seemed more comfortable since she was no longer burdened with worry. A while later, Castle finally opened his eyes, bright blue and twinkling, in spite of the fog of the anesthesia.

"You stayed," he said, cracking a small smile.

"Yeah," said Beckett curtly, staring down at the floor as she found herself suddenly unable to look at him.

"Why Detective Beckett, I do believe you were worried about me!" said Castle, dramatic as always.

"Oh please," said Beckett. "I knew you'd pull through."

Castle's smile broadened, for he couldn't help but notice that when she said it, she didn't quite meet his eyes.