Yandere!Leon/Kamui- noncon

Ever since she was a little girl, Kamui knew that her brother was meant to be something special. He was smart, innovative, and bound to become something great.

Sure enough, he had.

Leon was standing before her with a dark tome in his hand, and though his face and voice were calm, Kamui knew this was the angriest he'd ever been.

"Do you have anything to say for yourself, Nee-san?"

Kamui gulped, but forced herself to answer.

"I've been doing what I know is right."

A flash from Leon's tome sent her sword flying out of her hand.

"Wanting to do the right thing is fine, Kamui..." Leon said icily. "But I can't let a traitor walk free."
"Will you be able to kill me calmly, Leon?" Kamui narrowed her eyes as she prepared herself.
"Kill you? Don't be absurd." Leon grit his teeth for just a second before speaking again. "Your death isn't nearly enough to make up for it."
"Eh?"

Before Kamui could properly react, another flash from the dark tome caused her armor to fall apart. Then another began to tear at her clothes. She let out a shriek and covered herself.

"Now now, Kamui..." Leon's voice was shaking as he descended the stairs. "There's no need to be embarrassed. Didn't we used to take baths together?"
"That was... A long time ago." Kamui's eyes widened as he advanced toward her, pulling off his own armor as he did. "And we're not kids anymore, Leon."

Leon chuckled darkly.

"I suppose you're right, Kamui." He replied, but made no attempt to stop undressing. "We're adults, now. Let's do what adults do when they get naked."

He fired off another round of his tome when Kamui lunged for her sword. Kamui felt her arms being wrapped in tree branches that seemed to be pulling her to the ground. Before she could react, Leon was was already on top of her.

"Don't worry, Kamui." Leon smiled down at her. "It's my first time, too. I'll be gentle."

True to his word, Leon went slowly, massaging her breasts and rubbing her pussy. He seemed to be savoring the touch of her skin. If anyone were to walk in, only Kamui's bindings and protests would let them know that this wasn't a consensual encounter between lovers. Indeed, Leon put so much effort into making her wet that she almost didn't notice when he inserted himself.

"Kamui... Nee-san..." He moaned softly. "You feel even better than I imagined."

And he'd done so well, made her so aroused that she couldn't stop herself from saying,

"So do you."

For a split second, Kamui thought she saw him blush, but his face turned cold just as quickly.

"You're getting ahead of yourself, Kamui. This is a punishment, remember?"

Kamui let out a whimper as he started thrusting.

"Elise was inconsolable the night you left, Kamui." He leaned down to whisper in her ear. "Not even Camilla-nee-san could comfort her. Then again, she wasn't all there herself."

He gave a particularly rough thrust, making Kamui cry out.

"Marx-nii-san got drunk for the first time I ever saw him." Leon continued. "As for me, I immediately began forming a plan to bring you back. Then it hit me."

He looked Kamui right in the eye and said,

"If you got pregnant with mine or Marx-nii-san's child, you would have to come back."
"Pr-preg-"
"I don't know how Marx-nii-san feels about you. He loves you, but I don't know if he loves you as a sister or a woman. But I know for sure that I love you as a woman, Kamui." Leon smiled at her again, but there seemed to be something odd in his eyes. "I have for a long time."
"Leon..."
"Even before I knew we weren't related by blood. I know it sounds wrong, but I know I'll be able to make you happy, Nee-san." He ignored her protests as he continued thrusting. "I already know almost everything about you. And eventually I'll know how to make you happy like this, too."
"Leon, please sto-"

Leon cut her off by smashing his lips against hers. It tasted salty, but she couldn't tell if it was sweat or tears.

"Don't worry, Nee-san." He smiled at her again. "I saw the way that archer was looking at you, but I'll make sure he doesn't hurt you."
"Archer...? You mean Takumi?" Kamui blinked. "Leon... Please don't do anything to him."
"Why?"
"He's... important to me."

Leon stared at her for a moment, taking in her expression. His eyes turned wide.

"Nee-san, he's related to you by blood." He said slowly.
"I-I know, but I still-"
"He's related to you by blood, but he still looks at you like a woman. He needs to die."
"But I've been looking at him as a man!" Kamui pleaded with him. "Shouldn't I be killed?"
"Not at all, Nee-san. I love you." Leon shook his head as he resumed his thrusts. Kamui winced as she realized that he was getting close.

"And even if you don't love me in the same way, you will eventually." He leaned down to kiss her again. "We'll be very happy together."

Kamui squirmed as Leon finished. When she felt the tree branches release her, she thought about trying to grab her sword. Before she could, however, Leon smiled at her again.

"Nee-san." He said sweetly. His face looked so innocent that Kamui knew she couldn't fight him.

So she lay there on the ground until Leon pulled her up to wrap his cloak around her. He picked her up and carried her up the steps to where his horse was waiting.

"Let's go home, Nee-san."