A/N: So, this is my first story for Castle. I love this show and think that the chemistry is great. This is a one shot that just kinda came to me one day, and I wrote it down. There is a history for them, but I pretty much tell you everything you need to know. Hope you enjoy, and sorry if there are any mistakes.

Castle hastily paid the cabbie, tipping him over the minimum as a thank you for going the quickest way. He grabbed his two bags and smiled at the driver. The cabbie nodded his thanks, and once his fare was safely out of the car, he drove away in search of another taker. Castle turned around to face the edifice of the familiar apartment building. He smiled and hoisted his garment bag further up on his shoulder. The cool crisp air felt refreshing after the stuffy plane and cab. He took a deep breath, mentally laughing at himself for finding the polluted air of Manhattan refreshing. Castle pulled out his key and unlocked the lobby door. The wooden stairs leading up from the dark mahogany floor was a comforting sight. He began his ascent, anticipating Kate's face. It had been three weeks since he had seen her. This had been the longest they had been apart since they began dating eight months ago. Castle had missed her terribly, but knew that this would not be the last time they would have to be apart for an extended period of time. He had spent the last three weeks in Europe on a book tour for his second Nikki Heat novel. He had begged her to come along but she had declined, insisting that he a) did not need her, and b) she had a job to do in the city. He smiled as he reached the door and went to unlock it. He hesitated for a moment, fearing that if he were to open the door without announcing himself this might be his last moment on earth. He knew Kate was a well trained cop and would only shoot at someone if she knew they were a threat, but she was also a young woman living alone in a big city…with a gun. Castle thought for a moment and decided to risk it. He really wanted to surprise her. He opened the door slowly, hoping that if a gun was fired perhaps he would have enough time to duck the flying metal. "Kate! I'm home!" He grinned excitedly, waiting for her to run out from wherever she was…yet, nothing. It just now hit him that she may not be home, but she should be. It was three o'clock in the afternoon on a Sunday, where else would Kate be. "Kate, honey! You home?" Castle called out again as he set his bags down and walked towards her bedroom. "Katharine?" He heard some stirring and a low moan coming from the bed. He walked over and looked down to find her just waking. "Hey…" He said softly as he sat down next to her. Castle leaned down to give her a kiss, but stopped half way. "Kate, are you okay? You look horrible."

Kate had dark circles under her blood shot eyes, and her skin was pasty. "You really now how to sweet talk a woman don't you." She gave him a wry smile. Kate ran her hand lazily up and down his arm. "Hmmm…you're home early." Her voice was raspy, with a touch of emotion, less than she would have normally had.

Castle put his hand against her forehead. "Kate you're burning up. What's wrong? What are your symptoms?"

"Well, dad…" Kate gave him another weak smile, which he did not return. "I'm fine Rick. It's only a cold."

"What are your symptoms?" He drilled her with his best 'tell me now' stare.

Kate sighed and gave in. "I have body aches, chills, sore throat, coughing, and…that's it."

"Have you had any vomiting or diarrhea?"

She blushed, feeling awkward with this question. She knew she shouldn't, for pity's sake the man had seen her naked but for some reason this was weird. "That's none of your business."

"Kate, stop acting like a child. Have you or have you not had…"

"Yes, I have…both. And I've been running a fever. Happy now?" She asked as she closed her eyes and laid her head further back in the pillow.

"Have you seen anyone?" Kate shook her head no, and Castle groaned. "Kate…you know, once you're better I'm going to give you a long lecture about this and why it's important to…" Castle was interrupted by Kate sitting up suddenly, vomiting all down the front of her shirt and onto her bed. Castle jumped up and grabbed the trash can nearby, managing to place it in front of her before she wretched again. He tried to be the good boyfriend and hold her hair back, but the layers were making it difficult to keep all of it out of her face. She stopped and pulled her head up. Castle's heart ached for her when he saw the tears streaming down her face. He could tell she felt horrible, but did not want to admit it. "That's it. I'm taking you to the emergency room." She began to protest, but Castle stopped her. "No, you are going and that's final. I'll help you get cleaned up and then we'll head over to Mercy. They have an excellent E.R."

Kate decided not to argue, knowing that seeing a doctor was her best option. She slowly crept out of the bed and headed towards the bath room to get cleaned up. After she washed her face and changed her clothes, she pulled her hair back in a small pony tail. "I'm ready." She said softly as she walked out into the living room. She had on a pair of NYPD sweatpants and a long sleeve t-shirt. Her lounge wear was now her E.R. wear. She knew that this was going to be a long visit…it usually was when going to an E.R., and she wanted to be comfortable. To be honest, she did not think she could physically stand to be in anything else. "Do you have my purse?" She asked as he helped her into a jacket.

"Yep, I have your purse, a book for you to read but I highly doubt you feel like it and my computer so I can work on something if I need to. I figured we could just take your car." He grabbed the keys out of her purse and opened the door, making sure to lock it. Kate nodded and stood close to him. "Can you make it down the stairs?" Once she affirmed that she could, he took her arm and led her out to her car. He made sure she was in and buckled up, before making his way to the driver's seat. He pulled out and drove towards the hospital. Kate had laid her head back on the seat with her eyes closed. "You okay?"

"Stupid question." She muttered.

Castle chuckled. "Your right. Sorry. How about this one…do you think you will live?"

"Hope not. If you love me, you'll just run me over with the car."

Castle laughed again and reached over taking her hand in his. "I do love you, and that is why I can't run you over. I could always call any number of people in the local penitentiary who would probably be willing to do it."

"Hmmmmph." Kate moaned a little when the car went over a pot hole, jostling her and her weak stomach. "Are we there yet?" She smiled a little at him, hoping he understood her joke.

"You laugh now, but one day when our kids are asking you that, you won't think it's so funny." Castle caught his overt slip up, and glanced over to see if Kate had as well.

She had opened her eyes, and was staring at him (as well as she could). "You want to have kids? I thought you said…"

"I know what I said, but while I was away I thought a lot about it…and I want to have children with you. Kate, I'd be an idiot if I didn't." He squeezed her hand and glanced over at her, hoping she could sense his sincerity. "Well, I mean look at your ass…who wouldn't want to pass that on to the next generation?" Castle couldn't help himself; he had never been one who was comfortable with serious situations.

Kate lightly smacked his arm. "Despite your lovely sentiment, I want to have children with you too." She leaned her head back once more, trying to calm the waves of nausea that bombarded her body.

"Great! Wait, what about my butt?" He asked with mock offense.

"Eh…" She shrugged.

"Eh? What does that mean? I thought you liked my butt."

Kate peeled her eyes open once more and slowly turned her head towards him. "You have a lovely toosh, but that is not my favorite aspect of your body."

"Oh yeah…I know your favorite aspect…"

"No, that's your favorite aspect. Personally I love your arms."

"My arms?"

Kate shrugged, "They are so strong and muscular. You remember when we went to Saint Barts on our first vacation? We were lying on the beach watching the sun set, and you had your arms wrapped around me." Kate stared wistfully ahead of her, obviously far away from the small car and the city she knew. "That was the first time I ever remember feeling completely safe and content. I wanted to stay there forever." Kate smiled over at Rick, and squeezed his forearm.

Castle felt a wave of pride wash over him. He had been flattered many times by compliments about his body…and his manhood…but this was the best compliment he had ever received. "Well…" he said as he cleared his throat of the emotion dwelling there. "Now that that's settled, let's see if we can't figure out what's wrong with you." He pulled the car into a parking spot at Mercy General Hospital's E.R. parking lot. Castle got out and went around to help Kate out of the car, making sure he grabbed all of their stuff.

When they entered the lobby, he looked around for the admittance desk and located it across the room. "Why don't you sit down and I'll check you in. Have you ever been here before?"

"Okay and no." Kate walked slowly over to the waiting room and searched for a seat. The room was crowded with sick people, and Kate knew this was going to be a long evening. She managed to find a seat that would hold two people, almost like a love seat, and took up residence there. She watched as Rick returned with a clipboard and grim look on his face.

"Yea! Paperwork, everyone loves this. Let's see…name…Katharine Marie Beckett. Age, 29. Sex, she has it…a lot." Castle received a weak elbow to the arm and glare for that one. "Oh, it means which sex, my bad." He continued on through the paperwork, filling out what he knew and asking her the few he didn't. Kate was shocked at how much information Rick knew. She had been in relationships before, but never like this. Not even Will could have filled out this paperwork with as much ease. This sense of love, of belonging, overwhelmed her and she leaned over on his shoulder. "Feeling worse?" he asked.

"No, just…no." Kate didn't know how to explain what she was feeling.

"Okay, um…when was your last menstrual cycle?" He asked in a hushed whisper.

"Last week." She glanced up at him and laughed inwardly (she was too exhausted to laugh physically). "Having sex you can talk about, but talking about my cycle embarrasses you?"

"Shhh…look…I…" Castle cleared his throat awkwardly. "Are you allergic to anything?"

Kate let it slide, and they quickly finished up her paperwork. Castle took it up to the nurse who looked it over and waved Kate over. Castle met her halfway, telling her that he would save their seat. She sat down in a small booth like area off to the side. The nurse took her blood pressure, temperature, and reviewed the medical aspect of the papers with her. "101.7, that's pretty high." The nurse mumbled something else and turned around. She came back over and put Kate's I.D bracelet on her wrist. "We don't have any available rooms at the moment, but we'll try to get you in as soon as possible. If you can just wait where you were, we will call you back when we have an open room." Kate nodded that she understood and walked back over to her boyfriend.

"They said they'll call me back when they have an open room." She sat down slowly next to Castle, hoping that the wait would not be too long.

Castle nodded, and opened his arms. "Come here." Kate hesitated and looked up at him. "I'm not afraid of germs." She nodded and scooted over to him. He picked her legs up and laid them over his lap, allowing her to snuggle closer into his embrace.

Kate rested her head on his chest and shut her eyes. This was her favorite way to sit with him. She realized that she must look like a little kid, but she honestly did not care. She felt him tighten his hold on her, reassuring her that he was there for her. Kate tried to resist the exhaustion that plagued her body, but soon lost the fight and fell into a deep sleep.

Castle felt her body relax in his arms. He glanced down and looked at the sleeping cop. How could one woman mean so much to him? He had never felt this way about any woman in his past. He had loved Meredith, yes, but his love for Kate was different. There was no way to describe how much he cared for her, and there was nothing he would not do for her. As he thought about how wonderful she was, he regrettably admitted how not wonderful he was. He had made so many mistakes, done so many stupid things, and yet, she still chose him. Here was a woman who could have any man in the world and she had picked him. She was young, beautiful, smart, calm, funny, loving; the list went on and on. And what was he? Sure, he was charming, wealthy, and on his good days funny, but that was not enough. Shouldn't she be with a young guy, one who could share all the wonders of the world with her? Castle knew he wasn't decrepit or on his death bed, but he was a good deal older than she was. He had been married, had a child, seen and done so much that Kate hadn't…why didn't she want a man like her? Then Castle thought about what Kate had seen. She had lived through and seen more than most people her age, so in a way it made sense that she would want to be with an older man. Castle gently pushed a stray piece of hair off her face and smiled. He never thought that he would find himself mentally quoting The Sound of Music, but 'somewhere in my wicked, miserable past I must have done something good.' Kate was his (well not legally, not yet). He had every intention of proposing to her soon, but he hadn't found the right moment. He felt his heart ache as he stared further, she looked so sick. As he thought on her situation for a moment, his blood began to boil. He realized that she had not mentioned being deathly ill to him over the phone, nor had she seen a doctor. She could be so stubborn sometimes! Castle quickly calmed down, and made a note to chastise her about it later. He leaned further back in the seat and pulled her tighter to him, making sure she was snuggled up properly. He saw the many looks they were receiving. People were most likely questioning if it was really Richard Castle or someone who looked like him. And if it was, who was the woman? Daughter or girlfriend? Castle just smiled if he caught someone's staring eyes, and then they would jerk away, acting as if they had not been staring. This went on for a while. He glanced down at his watch to see that they had been waiting for two hours. 'This is ridiculous…' he thought as he tried to gingerly shift his weight. Kate was still asleep, which provided a little relief.

"Katharine Beckett." The young E. R. nurse called out across the waiting room.

Castle nudged Kate awake. "Hey, they are calling you back." Kate opened her eyes and registered what he was saying. "Can you make it, or do you want me to carry you?"

She shook her head no. "I can do it." She got up and walked over to the waiting nurse, Castle following quickly behind her.

The nurse led them down the twisting and turning hallways back to a large room with a glass sliding door and curtain. "Here you go. If you will put that gown on for us; we need you to take off all your clothes from the waist up, and the opening of the gown goes in the back. I'll be back in a few minutes." The nurse reeled off the information as if she was on autopilot, then left the room.

Kate did as she was told, and then climbed into the bed. "Oh, how I love hospital gowns and beds…they are almost as wonderful as the food."

"Well, if you had gone to a doctor when you first started feeling bad then you wouldn't be here." Castle mumbled as he helped cover her up with a blanket that had been folded at the foot of the bed.

"Man, I should have bet money on how long you would be able to wait before you got on to me."

"All I'm saying is…"

"I know what you're saying."

"Kate…" He was interrupted when the nurse walked back in.

"Hi, my name is Emma and I'm going to be your nurse while you're here. I see that you have had fatigue, muscle aches, vomiting, diarrhea, fever, and coughing." Kate nodded her affirmation of the symptoms. "Okay, well we're going to run a standard flu test. We'll check for both flu A and B. We're also going to do a strep test, and some blood work. After we get the tests, the doctor will come in and examine you and then once the results of the test are in we'll go from there okay."

"Sounds good." Kate said.

"Good. Now, don't hesitate to call me I'll be right out there at the desk. You're call button is right here on the side of your bed. The TV controls are there as well. I'll be right back with the flu and strep tests, and someone from the Lab should be here shortly." Emma smiled a soft smile and left the room as quickly as she had entered.

"Well, she seems like she knows what she's doing." Castle said as he sat in the chair near Kate's bed.

"Yeah, that's what you hope for when you come to the hospital." She said in a snarky tone.

"Hey, just because you're sick doesn't mean you get to be snarky."

"I'm always snarky." She gave him a small smile.

"You have a point there."

"Oh, and you're never a smart ass."

"Never…" Castle gave her a seductive smile and winked at her.

Kate rolled her eyes and leaned back into the bed. Emma returned shortly and swabbed Kate's nose and throat. Right as she was leaving, a young man entered with a rolling cart full of a sundry of needles, vials, and tubes to draw Kate's blood. Kate was relieved that although he was young, he was excellent at his job and quickly took her blood and left. "Rick…" Kate said getting his attention. He had been looking around the room, poking into cabinets and drawers. Castle snapped his head up and smiled. "Can you give me a piece of gum? I really don't want to breathe bad breath on the doctor." He nodded and grabbed her purse, laying it on her bed to shuffle through the contents. "It's in the pocket on the left. You're other left. No…not there…the other pocket. Just give it here." She demanded.

"Would you calm down! Here…now take this and hush." He said sarcastically as he handed Kate the gum.

She snatched it from him and stuffed it in her mouth. "Thank you." She said around the half softened piece.

"Katharine Beckett?" A middle aged man in a white coat asked as he stepped into the room. Kate nodded and he gave her a small smile. "I'm Dr. Wallace, and I'll be taking care of you today. Well, off hand I'd say that your symptoms seem to indicate the flu, but we'll see what your test results show. If you could sit up so I can listen to your lungs." Kate did as she was told and the doctor performed his examination. It was routine, the lungs, heart, eyes, ears, and throat. "Well, your lungs sound clear, so that's good. Your throat is red, and your ears have some fluid around them. I'll be back whenever your results come in." He left quickly, obviously scurrying off to another patient.

It wasn't long before Kate fell asleep again. Castle ran his thumb over the back of her hand, soothing not only her but himself as well. He never knew he could worry so much about someone other than Alexis; but seeing her so weak and vulnerable, not knowing what was wrong with her, made him realize how much he cared for her. All he wanted to do was to take her pain away, to make her feel better. Castle started to think back and see how much he had changed. He always knew that when the right woman came along he could grow up and be mature, now he had finally done so. Kate, too, had changed. She was much more relaxed and seemed to be enjoying life more. Castle was taken out of his reverie when the doctor returned and cleared his throat. He looked up and smiled at the doctor while he gently nudged Kate awake.

The doctor stepped forward and touched Kate's arm, helping the sick patient find the reason for she was woken. "Hello Ms. Beckett, sorry to wake you. Your lab results came back and you tested positive for Flu. Luckily it was Flu B, not A which means you have a less virulent strain. Unfortunately you are not in any of the high risk categories, so there isn't much we can do for you treatment wise. I'm going to give you a prescription for Tami flu, cough syrup and a note for work saying that you can't come back for a week. You should start feeling better soon, but I'm afraid you are just going to have to muddle through it."

"I'm a cop, so I can't be off work for a week." Kate said, frustration leaking into her voice.

"Well, I'm afraid that they will have to do without you. Look, I can't force you to stay at home…"

"But I can." Castle said sternly. His statement warranted an irritated look from Kate.

"Please take my advice and just rest. Your body needs time to heal itself, and going to work won't help it." He waited to see if what he had said made an impact on the cop's stubborn mind. She seemed to relax with acceptance, and nodded that she understood. "Good. Well, here is your prescription for the cough syrup and Tami flu, and the note for work. Just get lots of rest and fluids. I hope you feel better soon."

"Thanks." Kate said as the doctor left.

"Well, Detective…it appears that you will be spending the week with me!" Castle said as he gathered her things together.

"Great…that's always been my heart's desire." She said sarcastically, still giving him a small smile to make sure he understood she was kidding. "You know what this means don't you?" She said as she moved to get dressed.

"Yup, I get to have the whiniest house guest ever!"

Kate rolled her eyes. "No, it means you get to read to me."

"Kate, you know I hate reading aloud!" Castle whined.

Kate pulled her coat on and checked the room to make sure they weren't leaving anything. "I know, but you'll do it for me." Her statement wasn't demanding, but gentle and loving. She knew he didn't like to read aloud, but she loved to hear him read to her. She found it so soothing.

Castle wrapped his arm around her waist for support and the two began to leave. He leaned down and kissed the top of her head. "I would do anything for you." He said softly. The couple slowly made their way out of the hospital and back to Castle's car.

As they drove home to Castle's house (Kate kept clothes and other items there as well), Kate reached over and took his hand in hers. "Thanks for taking care of me."

"You're more than welcome. You would do the same for me."

2 Weeks Later- Mercy Hospital

"Hi, my boyfriend needs to be seen for what we think is the flu."

"Okay, if you can just fill out this paperwork then bring it back up here."

The nurse watched as the young woman walked over to a man slouched pitifully in a chair.

Kate sat down next to Castle. "Yea! Paperwork…let's see…name, Richard Castle."

A/N: Feel free to review! I love critiques...good or bad (just don't be mean about it. LOL)