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The first time Saitama fucks Genos, he's not sure what to expect. He's apprehensive, is afraid that he won't be able to get off because how hot could it be when it's not even a human? Genos has, well, problems, with human interaction. It's no fault of his own--only a matter of the trauma he's suffered. It'll be okay, Saitama convinces himself. The kid has a human brain. He's got emotion, he can enjoy himself, and most of all he definitely has some weird, pent-up feelings for Saitama.
Those feelings are things that Saitama reciprocates, to the extent that he's able. He's never loved anyone before, so the whole ordeal is new to him--he and Genos learn together.
They learn about feelings, they learn about each other's bodies; but most importantly, they learn about each other's weaknesses. They learn what elicits moans and whimpers, devious noises that can't be forced or faked.
Tonight, Saitama thinks he's found his favorite one yet. They've only fooled around a little before, kisses and oral explorations and touching, hot and heavy. But this is the first night that Genos has shown Saitama his pussy attachment and god is it ever perfect. It feels incredible, just as warm as what would be between a human's legs, and maybe even softer. Saitama's never had a preference for pubes or no pubes, but there's no doubt that he appreciates the lack of hair. Nothing, nothing at all, can separate his fingers from Genos's moist pink folds.
The responses are typical Genos, breathy and light, as his touch receptors at the tops of his inner thighs are teased and prodded. It's a shame, Saitama thinks, that Genos's chest is even more sensitive than whatever genitalia he's got installed down there at any given moment. The cyborg has explained in the past--the closer to his core, the more receptacles he has hiding beneath his armor to register sensation. When Saitama caresses his chest, kisses where a human's nipples would be, he can force the most wanton noises from Genos's lips.
But down here, there's not much. As much as Saitama hates to be disappointed in anything about Genos (because he shouldn't be, because Genos is enough for him no matter how different he is from the sex Saitama has been raised to think is typical), he wants to try something that has Genos whimpering and begging for more. It's not a matter of selfishness, but a matter of wanting to be sure that Genos feels just as good as he deserves to. It's not his fault that he's undergone extreme body modifications. One way or another, Saitama is determined to push Genos until he absolutely loses his mind.
The attachment is already wet, somehow, perhaps due to Genos's forethought and lubrication beforehand. It's easy for Saitama to pry Genos's pussy lips apart and find the little hole that's slick and ready to be stretched open. The pressure of Saitama's fingers against Genos's pussy doesn't seem to do much for the cyborg, but once he has a couple fingers inside and is poking and prodding around the mechanical innards, things change.
At first, Saitama is afraid to push or pull anything too hard. There's wires and what might be a couple of gears, and then some more solid pieces that must be connectors from something or other to something else. Hell if Saitama knows a thing about circuitry or engineering. Accidentally, his fingers brush a bundle of cables before pulling back out and accidentally tugging one too hard--
Genos absolutely sobs.
His voice modulates a little, higher than lower, and Saitama panics. "Are you okay?" All at once, he stops everything, until Genos is almost instantly begging for more.
"No, no, that one again. Do that again," he whines.
Saitama tilts his head, two fingers still lodged in his housemate's pussy. "The wire?"
"Yes."
Ah, well then.
Saitama goes for it, tugs the wire again, but harder. If Genos is telling him to do it, he trusts that it won't cause any damage. Genos knows his own body and its limitations better than Saitama does.
The blond's reaction isn't disappointing. This time, his golden irises flicker, and his voice glitches to static for a moment before returning to that lovely moan tinged with a hint of over-modulation. It's like there are two Genoses, one moaning at a higher pitch than the primary Genos, but Saitama knows better. It's just a sensory overload is all--he's found the solution for Genos's lack of sensation.
Hell, this more than makes up for it. He's never heard a voice so beautiful or a plea so appealing as Genos's little sighs while he arches his back and pushes down further onto Saitama's fingers.
"This isn't going to hurt you?" Saitama prods. Genos gives him a look, and he immediately regrets it.
"Trust me, Master," Genos says, and for the first time in the past few minutes, his voice is solid, not a whine or a glitch. Saitama knows he means business, and with his loving gaze and the way his fingers pick up speed inside his lover, Saitama apologizes.
In due time, there are three fingers, other wires discovered that have Genos absolutely writhing with pleasure, and Saitama is grateful. All he's ever wanted is to see Genos happy, pleasured, fucked out and clueless as he's overcome with sensations that Saitama himself can provide. Finally, his wish is coming true.
There's a buzz against the tips of Saitama's fingers that makes him pause again, but his momentary lack of motion has Genos absolutely keening for more. He'll tell me if I'm endangering him, Saitama tells himself. Trust is crucial right now. He's not going to fuck this up. The buzzing grows stronger and stronger until Saitama wonders if this is safe for himself or if he's actually getting electrocuted a little. He is who he is, after all, the strongest man in the world, and so he tries not to worry about it.
Besides, Genos's reactions and the look of absolute rapture on his face are worth any minor injuries Saitama might incur.
Soon, the buzzing ceases and is replaced by what sounds and feels like the occasional spark, and then the concept begins to make sense--electricity is how he gets off. It's like a nervous system, Saitama guesses, or something like it. Science isn't his thing, but he's read enough about cyborgs and has some ideas about how they might work, even if he knows little about them in real life.
"Please, Master, oh fuck, please." By now, Genos's words are barely coherent, but that only spurs Saitama on more. It's so, so satisfying to bring someone this close to the edge, but then Saitama realizes that he shouldn't get his hopes up again. Genos isn't human, so he might not be able to come. He'll set himself up for that disappointment he feels guilty for having if--
It's absolutely unmistakable when Genos reaches his climax. Everything Saitama has thought about cyborgs has been disproven in these past several minutes, and he's so infinitely curious about what else there is to discover.
Genos comes down slowly, his breaths fast and desperate while his eyes flicker with recalibration and little fans within him begin to whir with the start of his cooldown.
"The wires," Saitama says simply.
Genos can only nod before he loses consciousness to the need for a full system reboot.