Since it looked like none of them were done anytime soon, Benjamin resolved himself to help at least one of these poor souls. He thought about it and choose to check on Grace. He wasn't really afraid of being caught judging by the noise density in the two other rooms and how busy indulging themselves they seemed to be. Knowing how lusty the women in this world were, he also probably had ample time before they calmed down. Moreover, there was a high chance that they would tire themselves out and fall asleep as soon as they finished.
It seemed that Grace hadn't taken the time to lock her door and he quietly opened it, trying not to make any sound. When there was just enough room for him to see inside, he gave a small peek at the situation. She was lying on her bed on her back, still completely nude, her legs widely opened. Her eyes were closed, her focus intense, and she didn't notice him opening the door at all. She was violently plunging two fingers of her left hand into her pussy while the thumb of that same hand rubbed her clitoris at high speed. In parallel, the thumb of her right hand was also rubbing the bottom of her cunt hole whereas her major and index fingers were being sent inside her butthole, all of that with great coordination. He could feel that there was some great level of skill there; this was not the masturbation session of a beginner.
He moved inside, closed the door behind him while locking it, and approached her noiselessly until he was right next to her. He covered her mouth with his hand and she jumped with a start, extremely surprised at the contact, shouting in his hand with the sound of her cry being muffled. She opened her eyes and when she realized who was there, she blushed terribly and quickly removed her hands from her crotch, looking ashamed, instinctively trying to break free from his hand. He put one index in front of his mouth and whispered.
"Shhh. Calm down, Grace."
Hearing him, she progressively stopped struggling, until she was quiet again. He removed the hand which was blocking her mouth and she took a deep breath, looking at him, accusing.
"As promised, I came to help you when you couldn't take it anymore."
Her denouncing expression instantly left her and her eyes widened at his words. A few seconds more and she was blushing again, for a different reason.
"I could hear you from the hallway. Don't worry, I will follow your wish and send my sperm deep inside you."
As soon as she understood his meaning, her eyes bulged out and her expression contorted lustily. She was very horny after having been interrupted midway in her self-pleasuring session and he was only making things worse. She locked eyes with him while sending her hands back to her twat. She put two fingers from each hand inside her pussy and pulled them on the sides, opening her vagina wide, inviting. He could see the twitching and soaked flesh, ready for his intrusion, the intense smell of her sex and masturbation enticing him.
"Come into your big sister, Ben."
He didn't need more prompts than that and climbed on the bed, aligning his penis with her opening. Both participants looked very excited, their aligned fantasies soon to be realized. Without any other delay, he pushed forward, entering her warm folds, both of them sighing in pleasure. Pushing further, he was met with her hymen, which he quickly pierced in a stroke, not wanting to shame her by paying too much attention to it. She let out a small gasp but tried to remain otherwise stoic. He reached her deepest part and stopped for a moment, appreciating the situation. He had just deflowered his sister, the idol of his fantasies, and was going to have sex with her. The exhilaration was very strong, and, combined with the build-up so far, caused his cock to jerk inside her. Feeling his dick piercing her hymen, reaching her cervix, and spasming inside her pushed Grace to her limits, reaching her first orgasm, letting out a long and joyful moan.
"Mhmmm!"
Her pussy contracted strongly around his penis, releasing a wave of wetness, and the sudden shrinking of her hole also forced him to cum, suddenly ejaculating his semen deep inside her with a groan. He was very surprised to have come so fast. Was it really because it was her, after all?
Feeling his spunk filling her insides, she let out a satisfied sigh. She put one hand on her lower belly and gave out a wide grin of happiness.
"It feels so warm inside me. It is like a dream come true. I never imagined I would feel your semen inside me one day. I am happy, Ben. I am very happy right now."
"It is the same for me. I still can't believe we are really doing this. I love you, Grace."
"I love you too, my angel."
Benjamin bent over to kiss her and they shared a long smooch, passionately entangling their tongues and exploring each other's mouths. He could feel her large breasts against his torso and enjoyed the springy feeling. While kissing, he started to move his waist, slowly taking his dick in and out of her. She moaned in his mouth and he thought to give her some breathing space when she put her arms around his head and pulled it back to herself. Taking the hint, he continued to explore her insides on both ends, his tongue licking everything in her mouth and his cock remodeling her vagina to fit him. It always felt great to kiss during penetration and it was something he also welcomed.
He maintained his hips movements, leisurely enjoying her virgin pussy. Her creases were holding onto his penis as if to never let go and the feeling was amazing. Her face was also lost in the moment, full of lust, her tongue lazily moving around his mouth, her focus more on her cunt being constantly forced open by his cock. It didn't take long before she muffled in his mouth once again, reaching another climax, her walls squeezing him and her pussy flooding itself with waves of juices.