Fire Emblem Fates: Conquest, so siding with Nohr. Because of this, Elise is not dead. This will focus on Corrin/Kamui and Camilla. Takes place after their marriage. One-Shot lemon. I'm using their Japanese names.
Kamui was walking through the halls of the Nohr royal palace. He had stayed up too late and fell asleep outside by accident. He was enjoying the outdoors and cold too much. It was winter, and he had loved the cold air since he was little. Everything had been calm and quiet for a while since the last battle. Since he decided to side with Nohr, Ryoma and the Hoshidans had not attacked. He wondered if he wasn't fighting because now he had to fight his brother as well. Kamui sneezed.
"Bless you." said a familiar voice.
"Thanks, Leon." Kamui's younger brother came out from behind the corner, clad in all of his armor, sword at his side, and carrying a tome under his arm.
"Why do you look like you're going to war?"
"Because I am. The Hoshidan army has appeared once again, and we're heading out to meet them. Marx and I are commanding our forces."
"Why is this the first I heard of this?"
"I believe Elise convinced Marx to leave you and Camilla out of it, this time. You're newlyweds, and you need some time alone together."
"R-Right. What do you think of that, by the way?"
"We're all fine with it. We may have raised you as our sibling, but in the end, you're not at all related to us. We just want you to be happy."
"Th-Thanks-ACHOO!"
"Bless you. Are you okay? You look a little pale."
"I'm fine. I just fell asleep outside last night."
"...In the snow?"
"Yeah, I'm...just...great-" and he collapsed.
"Gah, Kamui! Are you okay?!" Leon bent down and felt his face.
"He was out there too long! His body temperature is low! Guards! Help me!"
X
Kamui opened and closed his eyes drowsily. He looked around a bit, seeing that he was in his room laying on his bed. There was a hot cloth on his forehead.
"Ugh...how long was I out?"
"A couple of hours." said a familiar voice. Corrin glanced towards the doorway.
"Marx..."
"You fool. What were you thinking sleeping outside in the cold? The doctors said you have slight hypothermia."
"...Are you still going to go fight?"
"Yes. Leon, Elise and I are leaving in a few minutes. Camilla said she'd stay here and look after you."
"Where is she?"
"She's preparing a hot bath for you. You need to warm up." Kamui flinched at the thought of finally bathing with his sister like she wanted and he didn't.
'No. She's your wife now. It's natural to do that.'
"Well, we'll be back in a few days. Get better." He left. Kamui wrapped a blanket around himself and walked around, exploring the castle.
"Almost every soldier is gone..." Just then, he saw Camilla walk down the hallway towards him. She was only wearing her lavender lace bra and panties.
"GAH! CAMILLA! WHY ARE YOU DRESSED LIKE THAT?!" he roared.
"We're married now. This bothers you?" she said, a hint of seductiveness in her voice.
"No, not at all! It's the others I'm worried about! Just because most of the guards are gone doesn't mean they're ALL gone! How would they feel if they walked down the hall and saw the princess in almost nothing?!" By now, his eyes had became angry white anime ones.
"I'm still wearing my undergarments, aren't I?" she asked innocently.
"THERE'S BARELY ANY DIFFERENCE! Let's just say that you have...ample proportions."
"Aw, thanks. Now follow me. It's time for your bath." Kamui flinched. Camilla took his hand and pulled him along. They entered the master bathroom and Kamui saw the giant bathtub filled with steaming hot water. He had to admit, it looked very inviting to him. Camilla walked over to the door and closed and locked it. She dipped her hand into the water, and turned to him.
"Alright, the temp is good. Let's get you in." Kamui felt slightly embarrassed as he dropped the blanket to the ground, revealing cream colored pajamas. He took off his shirt, and Camilla's eyes widened when she noticed his toned abs. He stood still for a few seconds, a faint blush on his cheeks.
"What's wrong?" asked Camilla. "You're not going in like that, are you?"
"It's just-"
"What?"
"It still feels kind of weird. I know we're married now, but I'm used to thinking of you as my sister."
"..." Without warning, Camilla quickly pulled down both his pants and underwear, making him yelp.
"WHAT ARE YOU DOING?!"
"I think you need to get over that problem with experience, Kamui. Hehe. My, what was that talk before about lacking as a man? You seem quite big to me. Or is it...only because you find it appealing that I'm only wearing my bra and panties?"
"Uhh...i-it's...I should get in the bath!" Kamui hurried and stepped in, sliding down until the water was up to his neck.
"Ah, this feels so good!"
"Hee hee, I'm glad." Camilla sat down on the edge, soaking her feet.
"...Camilla, why don't you join me? There's plenty of room for the both of us in here."
"Huh?"
"We still haven't bathed together yet like I promised you, and it's obvious that you're having a hard time holding yourself back from jumping in. It's written all over your face. Besides, you said I should get used to this kind of thing by experience."
Camilla looked ready to burst from joy. She stood up and unclipped her bra, letting it fall to the ground. Her breasts were massive, easily the biggest in the castle, and quite possibly the kingdom, too. She let her panties fall to the ground as well, finally revealing all of her body to Kamui. She walked down the steps of the tub and walked to the opposite side of her husband. He couldn't help but watch as her hips swayed from side to side. The Nohr royal family was easily better looking the the Hoshido royals. Marx, Kamui, and Leon were all show-stoppers for all of the women. Even his little sister Elise was good looking for her age. And of course, Camilla was drop dead gorgeous.
Camilla rested her hands behind her head, thinking back to when Kamui sided with them.
X
"Over here, Kamui!" yelled Ryoma.
"Brother!" cried his little sister Sakura.
"Return to us, Kamui." Marx offered.
"Big Bro!" Elise yelled.
"It's up to you, Kamui. Which side will you choose?" asked Marx.
As Kamui looked at his Nohrian family, he flashed back to all of his memories with them. But when he turned to his Hoshidan family, he didn't see very much. He had only recently met them, and to be honest, he didn't feel as comfortable around them. Kamui slowly turned to the Nohr army and began walking towards them. His Nohr siblings looked happy and relieved while his Hoshido siblings looked hurt and upset.
"...Why, Kamui? Why would you go to them rather than your real family?" asked Ryoma.
"You're not my real family. At least not to me." Ryoma and the others were startled and took a step back.
"Yes, you're my siblings by blood, but you're not my family. They are. I've spent my whole life with them. They raised me as one of their own, even though I was from the opposite kingdom. I've barely known you guys, and to be honest, I don't think I want to."
"Wh-What?! But they kidnapped you when you were a baby!"
"AND WHERE WERE YOU?! If I was SO important, SO precious to you, then where were you when I needed you?! Why weren't you looking for me, or trying to save me? I'm your little brother. I figure I'd at least be worth the effort, but apparently I was wrong. Goodbye, Ryoma." Kamui walked up to the rest of his siblings.
"I'm proud of you, little brother." Camilla told him. He ran his hand through her soft hair.
"Thanks. Marx, let's get going. We're going to withdraw."
"...Okay."
X
"Kamui."
"What is it?"
"Why did you decide to side with us?"
"You already know. You heard me at that battle, right?"
"Of course I did. But there's something more than that, I can tell. I spent more time with you than any of our other siblings, remember? I know you better than anyone." Kamui sighed.
"Yes, you do...to tell you the truth, I wanted to side with Ryoma."
"...Then why did you stay?"
"Because of you." She gasped. "I knew that what King Garon was doing was wrong, and that it would be easier just to defeat him through war rather than cause a rebellion from within his own kingdom. I'm ashamed to admit it, but I wanted to take the easy route out. But I realized something. I couldn't fight you, and I couldn't take the easy way out, because I know that you would have been disappointed in me, Camilla. I needed to stay with you." Camilla slowly stood up and started walking towards Kamui. She paused for a second before pushing her lips onto Kamui's, taking him by surprise. They had only kissed once before, at their wedding. Kamui was ready this time, though.
'She may be your step-sister, but she's your wife, first and foremost.' Kamui leaned in a bit more, surprising Camilla. She didn't think he'd respond like that. He deepened the kiss, and their tongues began dancing around. Camilla began moaning, and decided to sit on top of him so she wouldn't have to stand.
"You're not uncomfortable like this, are you?" she asked, interrupting their kiss.
"No, you're not that heavy. I'm fine." Camilla started draining the water so they'd have a bit more space. Since the tub was a deep soaking one, they'd have plenty of room if the water was gone.
"Camilla, are you sure you want to do this now? I don't want you to get sick..."
"It's fine. Besides, your skin is warm now, so your body temperature is pretty much back to normal. You weren't that sick."
Kamui spread his legs for her, so she began to work on his manhood.
"Ah."
"Does it feel good?" she asked, starting to suck again.
"Strangely enough, it does. I never really thought that you and I would ever get married and end up doing this."
"What makes you say that?"
"Truth be told, when you confessed, I was overjoyed. I have always wanted to marry you, but I always thought that your love for me was only motherly love at best."
"Oh, Kamui. I love you both ways: as a mother figure, but also for who you are. That's why we're having sex. If I didn't love you like this, I wouldn't have consented to it." She kept going, gradually increasing speed.
"Camilla, is this your first time? You're really good."
"Thanks. And yes, it is." Kamui reached around and began massaging her breasts. She began to moan even more.
"You like that?" he asked.
"Ohhhhh yeahhhh..." she said in a sexy voice. He was grabbing handfuls now and rubbing his hands around her soft pink nipples. Camilla was moaning louder and louder, turning on Kamui more and more.
"Are you ready?"
"Yes. Do it." Kamui inserted himself into her, and like she did, built up speed.
"OHHH! KAMUI! I'M-"
"ME TOO!" They both reached their climaxes, and after washing themselves off, they hugged each other.
"I'm proud of you for getting over your uncomfortableness."
"Thanks, Sis. That means a lot."
X
Marx and the others arrived back at the castle a few days after everything happened. Kamui and Camilla had found out that she was pregnant, and came up with a plan on how to tell their siblings. As it happened, the three of them were walking down the hall side by side. Kamui and Camilla were snickering behind the corner, waiting to see the reactions after this announcement. The two of them began walking towards the other three, hand in hand.
"Ah, Big Brother!" shouted Elise excitedly. "Are you feeling okay now?"
"Yes, thank you for asking."
"Did anything important happen while we were away?" asked Marx. The two of them kept walking, about to pass them.
"I'm pregnant." Camilla responded casually as the two waltzed past their other siblings. The other three had to stop for a moment and take in the information.
"I-I'm sorry. Could you repeat that?" asked Leon nervously. The two turned and smiled at them.
"Camilla's pregnant with my child." Kamui answered calmly. Elise and Leon's eyes popped out of their sockets before collapsing on the floor out of shock. Kamui and Camilla burst out laughing, leaning on each other's shoulders for support.
"Are you two serious or is this just a joke?" asked Marx. The two composed themselves.
"No, we're dead serious. We just wanted to break the news to you in a comical fashion." responded Camilla.
"Then that means that...you two...had...?" Marx's face was now red.
"Mm-hm!" hummed Camilla happily, draping her arms around Kamui's neck. This is what did Marx in. Now he fell over to join the other two on the floor. Kamui and Camilla started laughing again. Nine months later, a baby girl named Kanna was born to the two of them. She was very fond of both parents, as they each gave her equal love and attention.
The End.