She encourages him

"Well? What are you waiting for?" She demanded haughtily, her voice strained but steady. "Fuck her. Fuck my little sister."

Lucas grinned and was happy to take an order for a change. With renewed energy, he resumed ramming his cock into Eldwyn's tender hole, going as deep as he could go every time. Meanwhile, he kept his grip on her hair, yanking her head back with every thrust, dragging yelps of pain from her throat.

Lucas hadn't realized it before, but there was no longer just anguish in her cries. There was something else now, too. Not pleasure, exactly, but maybe joy? Kythril seemed to have also noticed it.

"He's... he's fucking you so hard, Eldwyn," she whispered, staring at Eldwyn's contorted face with undisguised awe. "He's just... using you for his own pleasure."

Eldwyn moaned. "Yesss... I'm his whore..."

"You love it, don't you?"

"Yesss," Eldwyn hissed through gritted teeth. "I'm a whore... I need cock... I want to suck... Uhhhnn... to be fucked..."

Kythril turned her head to look at Lucas, but continued speaking to Eldwyn.

"You want to be a good whore for your master?"

"Ahhh... yes... yes, I'll be good."

"And what do whores do?"

"Nnnn... they... they let themselves be... be fucked...?" Eldwyn guessed.

"Sluts get fucked," Kythril corrected her, shaking her head. "Whores get fucked for money."

"Mmnnnnn..."

"You want to be a whore, don't you, Eldwyn?"

"I... I..."

"You want to show off your body to horny men and women. You want to take all the cock he tells you to take. You want to get on your knees in shady alleys and suck off strangers for a few coins. You want him to sell you to his friends for the night, to use as they see fit. Admit it!" Kythril pressed on relentlessly, still staring at Lucas.

"Ohhh, fuck... yes, yes, I want..." Eldwyn whimpered breathlessly, her eyes half lidded.

"Tell him."

"I want to be a whore!" Eldwyn cried out. "Master, fuck your whore... Fuck me, fuck me, fuck me..."

Lucas had listened with amazement to the exchange between the two sisters and stunned at Eldwyn's final admission. A thousand ideas for things he could make her do flashed through his mind, each more vulgar and humiliating than the one before. An instant later, he felt his balls begin to churn.

"Fuck," he growled, releasing her hair to instead support himself on both of her hips as he rammed into her as hard as he could. He did not care his cruel use of her bruised ass drew tortured gasps from her straining lungs. His cock swelled and pulsed, and he **** it one more time into her clasping anus before he spew stream after stream of cum into it, soaking her insides with his sperm one last time.

Eldwyn could barely speak as he came inside of her. Her tongue lolled from her mouth as she panted for breath, her head drooping down now that he was no longer holding it up.

When his cock stopped pulsing, he reluctantly slid it from Eldwyn's asshole with a slow, wet pop. He collapsed backwards, panting to regain his breath.

Cum began spilling out of Eldwyn's gaping hole, but she went limp, sliding flat onto her stomach the ground, trapping most of it inside.

"She meant it, you know." Kythril said softly, stroking her sister's cheek with a strange expression on her face. "You don't have to hold back with her. She's not as fragile as you think."

Lucas untied Eldwyn's arms and lifted her into his arms. She threw her arms around him and mumbled wordlessly. He scanned the markings he'd inflicted on Kythril's body body. "Seems to me that goes for both of you."

She smiled faintly at that. "Good night, Lucas."

He turned around and headed for his bedroom, carrying Eldwyn.

"Good night, Kythril. You're a good sister."

He had almost left the library when she spoke up again. A whisper.

"I hope so."