This continues for a few days... but one day, something upsets her routine. While pumping at his organ, looking away, she gets a message on her phone while he is near climaxing and she stops manipulating his cock so she can take care of it. He groans at the sudden withdrawal of stimulation, bucking his hips, suddenly frustrated and needing her touch... and this sparks some dark desire in her, some pleasure in his discomfort. She begins to tease him for longer and longer before letting him achieve the overwhelming relaxing of release. Then, once sufficient samples of his heavy, hot sperm have been collected (more than sufficient, really. His powerful cock and balls never failed to flood the container she was provided to gather their hot, fertile product, until finally she had to custom order a gallon sized collection tube), her duties conclude, and she assumes she won't see him any longer.
But then, one night, she sneaks in after hours... she can't stop thinking about his monster cock... his whole body flexing wildly, straining with muscular exertion, his cock foremost, sticking straight up, rock hard, rigid like a flagpole, teased to the limit, bursting with desire... and she starts to tease him... she engages the gravity locks which bind him in place, enters the chamber, and starts toying with him. Teasing him, just to make him writhe.
She comes in and lifts her skirt, smiling as she reveals her panties. She pushes them down a little, just enough that he can see the edge of her pubic hair. It's downy and soft, like the rest of her. He can only imagine what her womanhood is like, buried in those panties, surrounded by warm pubic hair, bathing her femininity in her scent. Her femininity, gentle and ready for him... he bucks against the locks, crazed with desire, but he can't get to her, and that delights her.
She turns, lifts her skirt again, and reveals her ass. She tilts forward gently, slowly presenting herself to him, a shameless invitation to rough, aggressive coupling which he can't accept. It's maddening, but he can't reach her. His cock tenses, along with the rest of his muscles as he jerks against the restraints, fruitlessly.
Finally, she approaches him in nothing but panties, her gentle, squishy, warm, pillowy body just beyond the reach of his straining, rock hard cock... he's bucking towards her, desperately, but he can't touch her.
After hours of this cruel play, with a single finger, she gently grazes the side of his cockhead, and he orgasms instantly, spraying his hot, pent-up seed across the room, moaning with satisfaction, chest heaving and cock bobbing with each squirt as he spends himself entirely, painting even the opposing wall of the room with his fertility.
This doesn't do much to reduce his arousal, though. As soon as he finishes squirting his desire out, the sight of her soft, smooth body quickly causes his member to stiffen again. He could probably go on cumming like this for a while, she thinks. His large balls hang weighty in their sack, constantly churning with new seed, reinforcing his powerful virility in every way. But this one time will have to do. She picks up her folded up clothes, dresses again (gently teasing him all the while), and departs, her pussy soaked and burning with pleasure over the power she has, her clit almost stinging with delight--stepping carefully to avoid any contact with the massive streaks of hot seed on the floor, even as her warm cunt gently drools through her panties onto her thigh. At the feeling of her juice leaking onto herself, she pauses, mid-step, and smiles, delighted by an idea. She squats over his semen and pulls her panties to the side, taking care so that he can't see her soft entrance--only what comes out of it. He trembles with frustration at the sight of what her cunt drools out: a rope of viscous lubricant onto the floor. She looks up at him and smiles as the leaky slime of her arousal mingles with his steaming ejaculate. She returns her panties to place, and stands, proud of her emission. Her girl juice and his man juice mingle together on the floor with indescribable intimacy, which only adds to his frustration. Then she turns, gets dressed again, and leaves, leaving the beast straining fruitlessly in his frustration.